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NEXT STOP: VENUS!
An inferno fireball on the inside, a smooth yellow marble on the outside. Venus, the two-faced planet known as “heaven and hell.” Beautiful yet dangerous, Venus is rightfully named after the Roman goddess of love and beauty. In modern culture, people associate Venus with beauty products… and Venus Williams, the world champion tennis player.
Shrouded by its thick sulfuric cloud atmosphere, Venus is the second planet from the Sun and the hottest planet on average in the solar system. Also known as the Morning Star or Evening Star, Venus reflects sun light strongly, with a high albedo. Because Venus’ size is similar to Earth’s, Venus is sometimes to referred to as “Earth’s twin” or “Earth’s sister.” Other than size, however, Venus and Earth have nothing in common. Venus’ atmosphere rains sulfuric acid on the dry dessert-like surface! Its thick atmosphere (90 times thicker than Earth’s) composed of mainly CO2 traps carbon dioxide (greenhouse effect) and maintains a searing temperature on Venus. Venus may have harbored water once, but rising temperatures evaporated all liquid water, leaving a volcanically active surface. Mapped in 1990-1991 by Project Magellan, Venus’ surface comprises of 80% smooth, volcanic plains (70% plains with wrinkled ridges and 10% smooth plains) and 20% two highland “continents” Aphrodite Terra and Ishtar Terra. Venus has little impact craters but various volcanic features such as “novae” (star-like fracture systems) and “arachnoids” (spider-web-like fractures). Scientists know little about Venus’ interior without seismic data, but Venus’ size and density suggest an interior similar to Earth’s. Scientists have attempted to build probes to land on Venus’ surface, but all attempts failed (most only enter Venus’ atmosphere then burn up and crash). Venus’ clouds reflect and scatter 90% of sunlight, so scientists can only map its surface with radar. In fact, Venus’ atmosphere has an ozone layer and its clouds can produce lightning! Unlike any other planet, Venus spins from east to west, in a retrograde motion. Because Venus spins backward, its rotational period is longer than its orbital period; a day on Venus is longer than a year! Unlike Earth, Venus has a negligible magnetic field, unable to divert most solar wind. Like Mercury, Venus undergoes phases as seen from Earth. When Venus is in a crescent phase observers can actually see a mysterious ashen light. In the 17th century, Galileo proved the heliocentric theory with observations of Venus’ phases. Though Venus has no moons, scientists believe the planet had at least one that crashed into its surface. 10 million years after the collision, another impact changed Venus’ spin. Another possibility is that strong solar tides can disturb large satellites. Recently, the Transit of Venus occurred in June, when the planet crossed over the Sun.
MISSIONS: Venera, Sputnik, Mariner, Cosmos, Vega, Pioneer Venus, Magellan, Cassini, MESSENGER, Venus Express
*Many of these missions (Sputnik, Mariner) are series with only some successful and some only fly-bys; Venera is exclusive for Venus
- Order in Solar System: #2
- Number of Moons: 0
- Orbital Period: 225 days
- Rotational Period: 243 days
- Mass: 4.8685 x 10^24 kg (0.815 Earths)
- Volume: 9.28 x 10^11 km³ (0.866 Earths)
- Radius: 6,052 km (0.9499 Earths)
- Surface Area: 4.60 x 10^8 km² (0.902 Earths)
- Density: 5.243 g/cm
- Surface Pressure: 9.3 MPa
- Eccentricity of Orbit: 0.2
- Surface Temperature (Average): 735 K
- Escape Velocity: 10.36 km/s
- Apparent Magnitude: -4.9 (crescent) to -3.8 (full) | 0.812004 | 3.667591 |
It was not all that long ago that a “map” of our moon, of Mars, of a large asteroid such as Vesta, of Titan, or of any hard-surfaced object in our solar system would have some very general outlines, some very large features identified, and then the extraterrestrial equivalent of the warning on Earth maps of yore that beyond a certain point “there be dragons.” Constructing a map of the topography and geology of a distant surface requires deep understanding and data and lot of hard work.
Yet such an in-depth mapping is underway and has already resulted in detailed surface rendering of Mars, of Jupiter’s moons Ganymede and Io, and of our moon. And now, using both Apollo-era data for the moon and measurements from the Japanese lunar orbiter and currently flying American orbiter, the U.S. Geological Survey, in partnership with NASA and the Lunar and Planetary Institute, has produced a rendering of our moon that moves extraterrestrial mapping significantly further.
It unifies all the data collected using a variety of techniques and produces a map with well-defined geological units, with in-laid topography (on digital versions,) and with a guide of sorts for moon watchers on Earth. The red sections in the map above are the basalt lava flows that have the fewest craters from asteroid hits and so are the youngest surfaces. They are also the darker sections of the moon that we see when we look into the night sky at a full moon.
The maps are not at a detail to allow NASA mission planners to assess a landing site, but they do tell what the geological environs are going to be and so are a guide to what might be found.
The chief purpose of the map — in which 5 kilometers of distance are represented by 1 millimeter on the map — is to summarize the current state of lunar geologic knowledge.
Like comprehensive geologic maps of the Earth, it provides a framework for developing new theory and for determining the regional significance of surface explorations. In addition, classifying units into type and age by photogeology allows scientists to better understand the possible origins for many features.
“This map is a culmination of a decades-long project,” said Corey Fortezzo, USGS geologist and lead author. “It provides vital information for new scientific studies by connecting the exploration of specific sites on the moon with the rest of the lunar surface.”
Elevation data for the moon’s equatorial region came from stereo observations collected by the Terrain Camera on the SELENE (Selenological and Engineering Explorer) mission that was led by JAXA, the Japan Aerospace Exploration Agency. Topography for the north and south poles was supplemented with NASA’s Lunar Orbiter Laser Altimeter data.
This significantly upgraded mapping of the moon comes at a time when NASA — at the behest of the Trump Administration — is actively planning a return to the moon with astronauts. There are many difficult challenges ahead, but the first landing with astronauts is tentatively scheduled for 2024.
“People have always been fascinated by the moon and when we might return,” said current USGS Director and former NASA astronaut Jim Reilly. “So, it’s wonderful to see USGS create a resource that can help NASA with their planning for future missions.”
This animation shows the moon in rotation with shaded topography from the Lunar Orbiter Laser Altimeter. The moon is slightly tipped to make the poles visible. In reality, the moon does not rotate but rather is tidally locked. (NASA/GSFC/USGS)
The USGS is, of course, best known for its detailed maps of the United States and the Earth. But since 1963 it has had an “astrogeology” mission as well, centered at what became the USGS Astrogeology Science Center in Flagstaff, Arizona. In that capacity, it works closely with NASA and sometimes with scientists at other institutions.
As explained by James Skinner, a research geologist for the USGS in Flagstaff, astrogeological maps describe what is visible now in a way that allows scientists to know a great deal about the history of the subject.
The maps break regions into units — a volume of rock or ice of identifiable origin and age range that is defined by the distinctive and dominant, easily mapped and recognizable features that characterize it. These include petrographic features (detailed analysis of the mineral content and the textural relationships within the rocks), lithologic features (the characteristics of rock formations), and paleontologic features (the geological history of the rock formation.)
“A lot of what we do involves determining contacts or boundaries between different units and determining what units are on top of or below others,” he said. “It’s hard to say exactly what a unit is, and that’s why so much time and effort goes in to making those maps.”
The purpose of these solar system maps is to give a broad but detailed picture of the surfaces for future study and exploration, and this lunar map goes into unusual detail with features. To the geologically initiated, the map includes crater rim crests, fissures (identifiable cracks), grabens (valleys), scarps (cliffs or steep slopes), mare wrinkle ridges (tectonic features in the low-lying lava fields), faults, troughs (a narrow basin or geologic rift), rilles (meandering channels that look like riverbeds but are formed by lava flows), and lineaments ( linear features in a landscape that are an expression of an underlying geological structure such as a fault.)
This particular new lunar map is “unified” because it took into account all the assessments by previous astrogeological map makers of the moon and produced one standard version that can now be used for lunar exploration.
The Astrogeology Science Center has made comparable (though less detailed because less data has been collected) maps of Mars, the moon Ganymede, and the asteroid Vesta, with similar mappings underway for Mercury and Jupiter’s moon Europa. Other NASA centers and academic groups have produced maps of Jupiter’s moon Io and Saturn’s moon Titan, as well as other bodies, generally in connection with specific research they are involved with.
Mapping the hard surfaces of our solar system is an enormous achievement, unimaginable not that long ago. Remember those canals on Mars that were avidly and erroneously identified and traced by men and women of science little more than a century ago?
These maps make clear that we’ve come a very long way, but they also implicitly suggest just how little we know about planetary and lunar surfaces. While we can detect a fossil riverbed on Mars (a buildup of sediment that tells scientists that a river once ran there), we now know that there are billions and billions of planets beyond our solar system, and some of them clearly have hard surfaces. Will we some day map them, too?
That’s definitely for the far future since the planets are so much farther away than those in our solar system. But the technique needed to actually look at features of a very distant planet is known, though still in its infancy.
“Direct imaging” is a technique by which exoplanets are being discovered (and will in the future be characterized) through direct identification via powerful telescopes, rather than by measuring the indirect effects on their host stars. (A recent Many Worlds column looked at the possible detection via direct imaging of an exoplanet orbiting our nearest stellar neighbor, Proxima Centauri.)
While the number of planets identified via direct imaging remains small and most are gas giants, some of the results are remarkable. Below is a directly imaged movie of an exoplanet going behind the star Beta Pictoris and coming out again on the other side. The light from the host star is blocked so the exoplanet will not be lost in its blinding brightness.
The movie covers a period of four years and captures astronomical events occurring 63.4 light years away.
Many of the major telescopes of the future will feature variations on direct imaging, which is generally expected to become the gold standard for exoplanet discovery and characterizing in the decades ahead.
The Wide Field Infrared Survey Telescope (WFIRST), for instance, is being developed with a coronagraph to block out light from the host sun and to allow for exoplanet direct imaging — an architecture that would provide the first direct images and spectra of planets around our nearest neighbors similar to our own giant planets. WFIRST is a project very important to the exoplanet and astronomy communities, but not so much to the Trump Administration, which has sought to defund it twice.
The James Webb Space Telescope — now scheduled to launch in 2021 — has the capability through direct imaging to greatly increase the ability of scientists to characterize the atmospheres and temperature ranges of exoplanets. The JWST will not capture enough photons on its mirror to directly image the surfaces of planets, but future telescopes may well take us further in that direction.
While the JWST has a mirror diameter of more than 6 meters (21 feet), a space observatory that would have a mirror of either 8 meters (26 feet) or 15 meters (49 feet) in diameter is already well into the science and technology definition phase. Called the Large Ultraviolet-Optical-Infrared Surveyor (LUVOIR), it is in the running to be selected as NASA’s “great observatory” of the 2030s.
Then there’s the international ground-based Thirty Meter Telescope, ready for construction in Hawai’i with its 98-feet in diameter mirror. Work on the observatory has been halted because of protest from local residents who object to where it would be placed, but the TMT or other extremely large ground telescopes remain a near certainty.
If LUVOIR or the TMT become realities, then direct imaging of exoplanets will take a huge step forward. The resolution power will still not be enough and the star’s brightness will be too great to directly detect features on the surfaces of rocky exoplanets and map them. But the technological march to that day just might be underway.
Marc Kaufman is the author of two books about space: “Mars Up Close: Inside the Curiosity Mission” and “First Contact: Scientific Breakthroughs in the Search for Life Beyond Earth.” He is also an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer. He began writing the column in October 2015, when NASA’s NExSS initiative was in its infancy. While the “Many Worlds” column is supported and informed by NASA’s Astrobiology Program, any opinions expressed are the author’s alone. | 0.881635 | 3.911474 |
- A mysterious object called ‘Oumuamua, the first interstellar visitor ever detected, flew through the solar system in 2017.
- Most astronomers think it’s a comet, though ‘Oumuamua’s identity may never be fully settled.
- However, interstellar objects might visibly pass by once every 5 years. By the mid-2020s, powerful new telescopes may catch up to 10 per year.
- Scientists are developing space missions to rocket toward newfound interstellar objects and explore them with small robotic probes.
- Laser-propelled spacecraft like Starshot might one day be a fast and inexpensive way to check out weird space objects.
Without any warning, a mysterious object flew past Earth in October 2017 at a distance of about 15 million miles.
By the time astronomers discovered the cigar-shaped object, it was already careening out of the solar system at 110,000 mph — about 75 times faster than bullet shot from a gun.
Astronomers initially called it “1I/2017 U1” — with the “I” standing for interstellar, since the object’s trajectory strongly suggested it came from another star system. It represented the first interstellar object ever detected, so they eventually decided on the Hawaiian name ‘Oumuamua, meaning: “a messenger from afar, arriving first.”
Several telescopes on the ground and one in space took limited observations of ‘Oumuamua as it flew away. But the skyscraper-size object was too small, too fast, and detected too late to study in full. And now it’s too far and too dim to observe with our current technologies.
“This one’s gone forever,” David Trilling, an astronomer at Northern Arizona University who led Spitzer Space Telescope observations of the object, previously told Business Insider. “We have all the data we’re ever going to have about ‘Oumuamua.”
Scientists may never settle on the true identity of ‘Oumuamua. But the latest and best guess about the object’s identity is that it was an elongated, roughly 820-foot-long comet, according to a forthcoming study in Astrophysical Journal Letters (and almost certainly not an alien spacecraft).
Read more: A bizarre interstellar object called ‘Oumuamua continues to perplex astronomers a year after it vanished. Here’s why a few scientists still wonder if it was alien.
The astronomers who discovered and scrutinized ‘Oumuamua have not called it a day, though: They are already preparing for the next visit by an interstellar object.
In November 2017, Trilling and others published a study suggesting that current telescopes may see one such a cosmic interloper every five years. By the mid-2020s — after powerful new telescopes come online and begin hunting for dangerous asteroids — we may spot one ‘Oumuamua per year. Higher estimates suggest we could even expect up to 10 interstellar object detections per year, according to Harvard astronomer Avi Loeb.
“With this one, we were taken fairly by surprise,” Olivier Hainaut, an astronomer with the European Southern Observatory who’s worked on several studies of the object, previously told Business Insider. “With the next one, we are ready.”
Hainaut was referring to observatories, but he and others are also scheming something out-of-this-world.
Hainaut says at least two teams — one based in the US and another in Europe — are developing conceptual space missions to ride out and meet a future interstellar object. He added that the proposals would be “realistically affordable,” or on the order of $500 million (the price range dictated by NASA’s Discovery program).
“We had a workshop on this in October, and at the beginning of the workshop we said, ‘This is impossible.’ But after one week of hard work, we realized it’s not impossible anymore, it’s just difficult,” Hainaut said. “Impossible? That’s a problem. Difficult? As a first approximation, that just means expensive.”
How scientists plan to intercept an interstellar interloper
The biggest problem with trying to explore an interstellar object up-close is uncertainty about where it’d come from, when it will appear, and how close to Earth it might get.
That’s because the only data point we have is ‘Oumuamua itself.
To get around this, Hainaut said one option is to have a rocket on stand-by, and launch a relatively small spacecraft (to maximize range and flexibility) once the next interstellar object appears.
“You’d have to have the spacecraft ready in the hanger and hope you have a pretty big rocket,” he said.
But scrambling to launch a behemoth rocket — such as SpaceX’s Falcon Heavy, ULA’s Delta IV, Blue Origin’s New Glenn, or just maybe NASA’s Space Launch System — may not be practical or affordable.
“The other alternative is to park the spacecraft and the upper stage of the rocket in space,” Hainaut said. “You just leave it there, and when the object is discovered, you launch it.”
The closest parking spot would be low-Earth orbit, though one of several LaGrange points — neutral points of gravity in space between Earth and its moon (pictured below)— would give scientists maximum flexibility in reaching a target.
Parking any current upper-stage rocket in space for months or years may be too risky, though, because the vacuum of space is an incessant torture of scorching heat, freezing cold, space debris, and blasts of solar radiation. This increases the chances an upper stage’s electronics and fuel systems may stop working.
However, NASA has given ULA and Blue Origin some funding to develop advanced upper stages guaranteed to last for years in space. SpaceX is also working on a durable interplanetary vehicle called Starship that could survive in deep-space for a long time.
Could we ever catch up to ‘Oumuamua in deep space?
Those are just the possibilities with current and imminent aerospace technologies, though.
A couple of decades from now, a project called Breakthrough Starshot might provide a faster, cheaper, and wilder option.
The idea is to propel tiny spacecraft to another star system with ultra-powerful lasers, perhaps at around 20% the speed of light. Starshot, which was announced in April 2016, was dreamed up by Loeb at Harvard, Stephen Hawking, and other researchers. The project is backed by a Russian-American billionaire.
As a test run someday, such robots could be sent to catch up to and study ‘Oumuamua in deep space.
“If we had the Starshot infrastructure, it would have been trivial to chase down ‘Oumuamua,” Loeb told Business Insider in an email. “Even with a speed of merely a tenth of a percent of the speed of light (namely a factor of 200 smaller than the ultimate goal of Starshot) it would be possible to catch up with Oumuamua in a matter of months by sending a cell phone camera that weighs a gram.”
Read more: The speed of light is torturously slow, and these 3 simple animations by a scientist at NASA prove it
That’s not to say it would be easy. By the time a Starshot nanocraft could actually launch, ‘Oumuamua would be much dimmer — which means the probe would have to get pretty close to take a photo. When traveling at incredibly high speed, that’s a difficult maneuver to get right.
“In my view, it makes much more sense to wait for the next interstellar object to be discovered,” Loeb said. “If we catch it on its way to us, we could even contemplate a space mission that will fly by it or even land on it.”
Hainaut’s conceptual proposals rely on more traditional chemical rockets, but he said he’d welcome an innovative solution like Starshot.
“The Breakthrough Starshot is extremely interesting. The problem is that the laser technology that is required is far from being ready,” Hainaut said. “I hope it will be one day.”
SEE ALSO: Smart aliens might live within 33,000 light-years of Earth. A new study explains why we haven’t found them yet.
DON’T MISS: An alien hunter explains why extraterrestrial visitors are unlikely — despite the US government’s UFO evidence
Join the conversation about this story »
NOW WATCH: Astronomers have discovered a bizarre-looking object that came from outside our solar system | 0.876977 | 3.416127 |
For mass transfer in a binary system, one star must fill its Roche lobe. What determines whether a star in a binary system will fill its Roche Lobe? How will I calculate it? I can't find any mathematical formula that shows any equation of mass transfer.
One should distinguish the "Roche limit" from the "Roche lobe," as the latter is what you need when you have two objects of similar mass, like a binary star. The Roche lobe is an effective equipotential in a frame that cororates with the orbit of the binary (assumed circular). The equipotential is "effective" because it includes both stellar gravities, and also the centrifugal force from the rotating frame. The Roche lobe is not only an effective equipotential, it is the last one that is closed-- any equipotential further out connects to infinity and cannot correspond to material in equilibrium that is corotating with the orbit. From the side, this last equipotential looks like a kind of infinity sign. Material outside that "infinity sign" has to start moving in the rotating frame, bringing in coriolis forces and in generally leading to complicated motion. However, if close to the Roche lobe, the gas tends to flow through the nodal point at the center of the "infinity", so tends to be transferred from the domain of gravitational attraction of one star to the other. That's "mass transfer."
Setting up the calculation of the Roche lobe is fairly easy because you only need the two gravities and the centrifugal force at the orbital period. But it is a difficult set of equations to solve, and even at the research frontier, is usually approximated rather than calculated exactly. No doubt this is the source of your difficulty.
Why one star fills its Roche lobe is a consequence of stellar evolution, often as one star attempts to evolve into a red giant or asymptotic giant. Before it can reach its giant radius, its outer layers encounter the Roche lobe, and pass along it through the central node (the "Roche point") and may ultimately end up attracted to the other star. This is what is thought to have happened in Algol, for example, which is a binary where the star with the greater mass now started out as the star with the lesser mass (because it gained from its companion). The rate of mass transfer is also difficult to compute, because it depends on how fast the mass-loser is evolving. It is only its evolutionary rate that causes the "Roche overflow," so the mass transfer rate is pegged to the evolutionary rate, which is largely due to rate of fusion that adds mass to its core.
If you're up to deriving the Roche limit, here is something that might be useful to your study. This webpage offers its derivation, based on the Newton's equations. | 0.845937 | 4.045127 |
HETDEX: The HET Dark Energy Experiment
Astronomy is competitive. To attack the big questions, we need to keep investing in forefront facilities. The University of Texas McDonald Observatory can achieve this in a very cost-effective way by upgrading the Hobby-Eberly Telescope (HET) and adding to it innovative new instrumentation. At the same time this upgrade will allow Texas astronomers to answer the biggest question in all of science.
Dark Energy and Dark Matter
We only understand 4% of what makes up the universe. The nature of dark matter and dark energy is the greatest and most exciting problem in all of science. Dark energy is the name given to the phenomenon of the accelerating universe, whose expansion is speeding up over time.
Science does not know what dark energy is. Is it new particles? Energy of the vacuum of space? A change in the law of gravity? We know how to find out. Texas astronomers can differentiate between these possibilities with new facilities. Explaining dark energy will cause a fundamental change in our understanding of the laws of nature.
The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX)
- HETDEX is the quickest and most cost-effective project to uncover the secrets of dark energy. It uses our large Hobby-Eberly Telescope and an innovative new instrument called VIRUS to survey the sky ten times faster than existing facilities worldwide.
- HETDEX is competitive with projects costing billions that are being proposed worldwide. Only three projects including HETDEX are currently moving forward. Of these, HETDEX is in the lead at a cost of $34 million — lowest cost of all proposed projects.
- HETDEX will make the largest map of the Universe ever, traced by a million galaxies.
- HETDEX looks back in time 10 billion years.
- HETDEX will measure how dark energy changes with time: It is better than other experiments at measuring the change because it looks back so far in time; a change in the properties of dark energy will be the key discriminator between the different possibilities for the nature of dark energy.
HET Upgrade and VIRUS
HETDEX will upgrade the Hobby-Eberly Telescope to look at 25 times more sky, increasing our field of view to half the area of the Moon. This will be accomplished by adding new optics and an innovative new instrument to the HET, known as VIRUS. The VIRUS instrument will consist of 150 copies of a simple spectograph, replicated cheaply. We are pioneering this approach to save on cost and to remove engineering risk by prototyping the unit.
How HETDEX Works
Together, the upgraded HET and VIRUS will execute the largest astronomical survey ever made. This facility will be unmatched in the world, giving Texas astronomers the ability to survey the sky 10 times faster than any existing facility worldwide. It has the power to address the problem of dark energy. In short, the HET makes HETDEX work.
HETDEX Fast Facts and Benefits
- It will answer a fundamental question about our Universe and generate great public interest.
- Led by UT Austin with strong participation from Texas A&M and a small number of other institutions in the US and Germany.
- The project and fantastic facility that will result will attract the best researchers and students to Texas, which in turn seeds the next generation of scientists and engineers.
- The project Web site — HETDEX.org — has already proven to be a great resource and investment.
- HETDEX will be a catalyst for attracting the next generation into science.
- There is great need to attract and retain K-12 students in science, and the McDonald Observatory Education and Outreach Office has the means to bring this exciting story to teachers and students and use it as a tool to generate excitement that will follow through to the workforce.
- We are at a revolutionary time in science and Texas can play a pivotal role that will be reported in K-12 and university textbooks for decades.
- The University of Texas at Austin McDonald Observatory
- Texas A&M University
- Max-Planck-Institut fuer Extraterrestrische Physik
- Pennsylvania State University
- Ludwig-Maximilians-Universität Munchen
- Astrophysical Institute Potsdam | 0.8044 | 3.533034 |
A new study by the Australian national University helped to create a three-dimensional map of the magnetic field in a small wedge of the milky Way galaxy that paves the way for future discoveries that will improve our understanding of the origin and evolution of the Universe. Study leader Dr. ARIS, Trices from the research school of astronomy and astrophysics ANU said that this was the first study that allowed topografichesky to measure the strength of the magnetic field of our galaxy.
Magnetic map of the milky Way
“Our work paves the way for future discoveries about the evolution of the milky Way, stars and planets and the early stages of the Universe,” says Dr. Tritsis.
The magnetic field of the galaxy and space dust act as a veil that covers the radiation of the early Universe — known as cosmic microwave background — and stirring scientists to test the cosmological model of the Universe evolution.
For comparison, 15 µg (microgauss), which are usually measured in the interstellar medium is 10 million times less power magnet on the fridge. Despite the small size and the length in the tens or hundreds of light-years, it is extremely important for all processes that we described earlier.
“Now we have the means of mapping the magnetic fields for all regions of our galaxy, allowing us to better understand the evolution of the Universe,” says Dr. Tritsis. “This work proves that such an ambitious study is feasible. Our next step is to create the first complete three-dimensional map of the magnetic field of the galaxy and explore all the other astrophysical processes that depend on it”.
The detected strength of the magnetic field of a galaxy was much higher than previously thought.
Most models that predict the strength of the magnetic field of our galaxy for each location and distance from the Sun, based on observations that can not explore the magnetic field in three dimensions. The new model will help to understand how high-energy cosmic rays pass through our galaxy.
Cosmic rays — extremely energetic particles, the energy of which sometimes far exceed those that can achieve.
“Understanding the structure and strength of the magnetic field we can increase our chances to find the location of the sources of these very energetic particles and will be able to explore the new physics at extreme energies”, the researchers say. The study was published in The Astrophysical Journal.
Don’t forget to subscribe to our feed with newsto be aware of. | 0.838199 | 3.872332 |
MESSENGER spacecraft provides first global topographical model of Mercury
Using data captured byNASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging(MESSENGER) spacecraft, a team of scientists has constructed thefirst complete digital elevation model (DEM) of the planet Mercury. Thenewly-released map reveals the geographical highs and lows of theinnermost planet in our solar system, as well as highlighting anumber of fascinating surface characteristics.
In total, the MESSENGERspacecraft spent four years in orbit around the planet Mercury.During this time, and under the constant protection of its ceramiccloth sunshade, the resilientlittle spacecraft characterized Mercury with a suite of advanced scientific instruments, and captured almost 300,000 images of the planet's baked, barren surface.
The publishing of thenew global map represents the 15th and final release ofdata from the MESSENGER mission. The spacecraft itself ended itstenure around Mercury almost a year ago today. Having run out of theall-important fuel needed to maintain its orbit, the probe wasleft to smash into the surface of the planet it had spent itsbrief operational life observing.
Stitched together fromover 100,000 smaller images, the newly-released map serves as afitting embodiment of the work carried out by the late roboticadventurer. The map displays in great detail the topographicalcharacteristics of the tortured planet, most notably the vast collection of impact craters that have accrued in part thanks to Mercury's lack of any significant from of atmosphere.
At its lowest point,Mercury's surface plunges some 3.34 miles (5.38km) beneath its average level. This deepest depth islocated in a double impact crater known as the Rachmaninoff basin.Conversely the highest point on the planet's surface stretches 2.78miles (4.48 km) towards Mercury's tenuous exosphere.
Previous attempts byMESSENGER to create a topographical map of Mercury's surface werethwarted by the spacecraft's highly eccentric mapping orbit, whichmade it difficult for the probe's Mercury Laser Altimeter (MLA)instrument to acquire accurate readings on the planet's southernhemisphere.
Furthermore there areinherent difficulties in imaging Mercury's north polar region.Ordinarily, the Sun is low relative to the polar horizon, creatinglong shadows that work to mask the characteristics of the rocks present in the terrain.However, by utilizing the probe's Mercury Dual Imaging System (MDIS) to capture the region in five separate narrow-band filters when the shadows were at their least obtrusive, the team was able to complete the global map.
Whilst the map is thefinal major release of data from the MESSENGER, it is not the end ofthe spacecraft's legacy. Beyond characterizing one of our closest planetaryneighbors, mission scientists believe that the 10 terabytes of dataprovided by the probe will be of great use to astronomersattempting to unlock the complex formation process that created the rich andbeautiful Solar System we exist in today.
Scroll down to view an animation of the newly released map of Mercury. | 0.81494 | 3.667205 |
The Calan-Hertfordshire Extrasolar Planet Search
Within the New Worlds Lab we conduct a number of small and large surveys for planets, in particular we have been running the Calan-Hertfordshire Extrasolar Planet Search (CHEPS) since 2007. CHEPS is a survey focusing on the detection of planets orbiting the most metal-rich stars in the galaxy. Metal-rich stars are those with the most metals like iron in their atmospheres. The significance of metals when it comes to planet search is that it has been well established that metal-rich stars host a higher fraction of gas giant, or Jupiter-like, planets orbiting near to the star. More recently, the CHEPS project has shown that the opposite might be the case for the lowest mass planets, the so called super-Earth planets, those planets with masses a few times that of the Earth.
The CHEPS project uses the radial velocity method to detect planets, and the radial velocity method is an indirect method that works by breaking the star’s light into its constituent colours, or its spectrum, then using any dark bands in the light coming from atoms in the star’s atmosphere that is blocking some of the light (absorption lines) to measure a velocity of the star as it moves towards us and away from us. This velocity is given by the motion of the star that is induced by the gravitational interaction between the star and any orbiting companions. You may think this velocity must be small for small planets, since the stars are so much more massive, and that is indeed the case. However, instruments like HARPS that are located at the European Southern Observatory’s la Silla Observatory in Northern Chile, can measure the velocity of stars to a precision better than 1 meter-per-second!!
Thus far, as part of the CHEPS, we have discovered brown dwarfs orbiting in the so called ‘brown dwarf desert’, over 10 new planetary systems consisting mainly of gas giant planets, multiple planet systems, and a low mass system that hosts a hot Uranus-mass planet, which is also likely the most metal-rich star ever known to host a planet. Furthermore, and somewhat more importantly, we have shown that there appears to be a lack of planets with masses less than that of Neptune (17 Earth-masses) orbiting those metal-rich stars, which indicates that these stars likely form large planets quickly, not leaving behind many small planets.
High Contrast Imaging of Long Period RV Trends from the CHEPS and EXPRESS Surveys
While most of the group does research on the radial velocity method of detecting extrasolar planets, we also do research in looking for low-mass stars, brown dwarfs, and planets using the direct imaging method. Whereas radial velocities measure the changing velocity of a star due to the gravitational interaction by an orbiting companion to find planets, direct imaging takes pictures of stars to try to *see* any orbiting companion. While this might seem easier to do, it is actually very difficult as a star could be about one-billion times more bright than the planet. This would be equivalent to trying to find a firefly near a lighthouse, many kilometers away! Luckily we have some ways to find orbiting companions using adaptive optics (AO), where the AO system is able to correct for turbulence in the Earth’s atmosphere (allowing us to see the region very close to the star), along with coronographs that vastly decrease the star’s light by blocking it out. We use instruments such as SPHERE at the Very Large Telescope and Magellan Adaptive Optics at Las Campanas Observatory, both of which use various methods to allow us to find faint objects close to their stars.
At the current time, most of the planets being discovered with this method are very young and hot. The Sun, for example, is an old star, about 4.5 billion years old, and therefore its retinue of planets are also very old and hence very faint. While we will be able to observe planets like Jupiter around nearby old Sun-like stars when the European Extremely Large Telescope (with its giant 40 meter mirror) comes online in 2024, for the present time, we can search for low-mass stars and brown dwarfs orbiting a Sun-like or less massive star. This allows us to map out an orbit of the object over time, giving us a direct measurement of the companions mass using Kepler’s third law. With this mass measurement, we can better understand the physical processes that are happening in the least-massive stars by comparing them to what we would get from computational models using physical theories, as well as the known relationship between a star’s mass and its brightness. You can see one of these low-mass stars in a SPHERE image we obtained here (circled in red), which is about 60 times fainter than, and 4 billion kilometers away from, its host Sun-like star.
The RAFT Survey
The Re-analysis of Archival FEROS specTra (RAFT) project focuses on the detection of planetary systems using the radial velocity technique applied to spectra that was previously observed with the FEROS instrument, but using our new analysis program. The stars we focus on as part of this project are mainly sub-giant and giant stars, which are stars generally much larger than our Sun, and further along their evolution, or closer to their death-beds.
As part of RAFT, we also work on the characterization of the stars we want to use to search for planets. This is very important because what we observe in the end are the stars themselves, not the planets directly, so we need to understand the type of star before we detect the planets. Therefore, within the New Worlds Lab, we are working on an automatic code that computes the temperature, metallicity (amount of metals in a star’s atmosphere), surface gravity, micro turbulence, mass, age, and abundance distribution of different elements. We plan on using this code to compare the characteristics of stars in different evolutionary states, and to understand the systematics produced by the different sources of data used by the astronomy community.
The Rocky Planet Search
This research is focused on the detection of small rocky exoplanets orbiting the nearest stars to the sun. The detection method we use is commonly referred as Doppler Spectroscopy. As mentioned above, this method consists of measuring the radial velocity of the star with respect to the Sun. If the star has a companion orbiting around it, we can detect how much it wobbles due to the influence of the companion.
We use very precise (~1 m/s) spectrographs installed in the telescopes located in Northern chile to hunt for these small planets such as the Carnegie Planet Finder Spectrograph (PFS) at the Magellan Telescope in LCO, HARPS at La Silla, and CHIRON at CTIO. We also use data from spectrographs located in the Northern hemisphere such as HiRes at Keck (Hawaii) and APF at Lick (California).
Once the radial velocities are computed, we use a statistical model to look for the signatures embedded in the data. The Bayesian approach we use performs Makov Chain Monte Carlo analysis (based on the Metropolis-Hastings algorithm) and this is used to estimate the most statistically significant set of orbital parameters that support the data (i.e. the best set of characteristics for a companion planets orbit around the star), taking into account the stellar activity. Stellar activity is important since it can introduce periodic signals that are not due to the presence of a planet orbiting the star. We use spectral lines such as the CaII H & K lines to monitor the chromospheric activity of the star. The main goal of this project is to constrain the frequency of low-mass rocky planets orbiting nearby stars. | 0.923325 | 3.858242 |
Eris. Ever heard of it?
Didn’t think so.
Eris is the reason Pluto — poor old Pluto — is no longer deemed worthy of being called a planet.
In the good old days (otherwise known as the Eighties), we learned about the solar system in school. Back in 1986, the reappearance of Halley’s Comet was not treated as a harbinger of doom, but as an unmissable opportunity to foist random space facts onto unsuspecting school aged children that was too good to miss. In educational parlance, it heralded the arrival of a “teachable moment” in gloriously action-packed colour, and our lessons were filled with tales of the Milky Way, black holes, quasars, nebulae (the Horsehead Nebula was a particular favourite), red dwarfs, Magellanic clouds and — of course — the planets. All nine of them.
Nine planets — just like the Nine Nazgul in Tolkein’s trilogy, or the nine circles of hell in Dante’s Divine Comedy. We even had a mnemonic to remember them, in order of their proximity to the Sun: My Very Elegant Mother Just Sits Under New Potatoes. (Admittedly, like many mnemonics it doesn’t make much sense, but the critical factor here is the presence of Potatoes…er, I mean Pluto…at the end, way out in the darker reaches of the galaxy).
But then in the early Nineties, Pluto’s planetary status started to wobble. Astronomers discovered the Kuiper belt, a ring of objects way out past Neptune. Big objects. Dark mutterings began to be heard in astronomical circles, that Pluto — named for the God of the Underworld, no less — was only a dwarf planet.
And then, in January 2005, a new body was discovered. And this object, as it turned out, was bigger than Pluto.
Yep, you guessed it: Eris.
In one fell swoop, Eris — appropriately named after the Goddess of Strife and Discord — sent Pluto packing from the planet list, relegating it to the ranks of TNO’s (Trans-Neptunian Objects) and forcing the International Astronomical Union to come up with a formal definition of “planet” at a conference in the Czech Republic in 2006. And while the cynic in me suspects that all those stargazing scientific types really wanted was a good excuse to visit Prague, the upshot of their Eastern European sojourn was that Pluto was down-graded. Reclassified. Failed to pass the planet test.
To say the decision to strip Pluto of planetary status was controversial would be an understatement — even in astronomical circles. Apparently less than 5% of astronomers voted to support the new definition, which could hardly be construed as a representative sample in any
dictatorship democracy. I, for one, would agree with Alan Stern, who asserted that “the definition stinks, for technical reasons” (and if you’re similarly inclined, you can read about why here).
Apparently, Pluto does not meet Criterion 3 of the IAU’s definition of planet: that the object “must have cleared the neighbourhood around its orbit”.
I mean, seriously people — is that it? If clearing the neighbourhood is all they needed Pluto to do, surely we could have sent someone out there to sort it out? The US Marines, perhaps? The French Foreign Legion? Hell, I think even the New South Wales Police Force would be happy to take on the task of clearing a neighbourhood.
To be fair, I do understand that the IAU had something more along the lines of gravitational dominance and of there not being other bodies of comparable size other than its own satellites in the vicinity — and let’s face it, Pluto is light years ahead of Earth on the satellite front, with five moons to our one. But even when the scientific definition is considered, the celestial finger is still pointing in one direction, and one direction alone: towards Eris. Because Eris is the body of comparable size to Pluto that stops it from clearing the neighbourhood.
My Very Elegant Mother Just Sits Under New…
But now, finally, true believers around the galaxy are being rewarded for our continued faith in Pluto: our favourite former planet is making headlines once again.
More than nine years after its launch (yes, nine…there’s that number again), NASA’s New Horizons mission, tasked with understanding the formation of the Pluto system and the Kuiper Belt is rapidly approaching its destination. At the time of writing this, there are less than four hours before the New Horizons spacecraft flies closest to Pluto, when it will be only 12,500km from the Plutonian surface. The images the spacecraft will send back to Earth will be the first we have ever seen — which is arguably the most exciting thing to have occurred on July 14 since the storming of the Bastille in 1789.
I can’t wait to see those pictures!
Though I would imagine that Alan Stern, the aforementioned Defender-of-All-Things-Plutonic, is pretty keen on seeing them too. After all, he is the principal investigator on the New Horizons mission. | 0.945886 | 3.509789 |
NEW YORK – The Interstellar Probe, an ambitious concept for traveling to the edge of the solar system, is approaching reality. During a panel event held at the Club of Researchers here on October 17, scientists discussed the idea of sending a space ship 90 billion miles (19659002) away from Earth and its planets around our solar system like a goldfish in a bowl, which in this case it is the limit produced by the sun. Now imagine if a fish could send a probe out of the vessel to learn about its place in your living room. This funny thought is a bit like the idea behind the interstellar probe.
Sending scientific instruments to the edge of the heliosphere or area of sunlight is like going to the edge of a fish bowl. Going beyond the heliosphere and looking back at the solar system – beyond the bowl – could inform a whole new scientific perspective about our place in space.
Related: Wild & # 39; Interstellar Probe & # 39; Mission Idea Gaining Speed
Space technology has evolved to enable new science missions. Geographic studies are supported by technologies ranging from orbiting space telescopes to cameras aboard close and personal missions such as Cassini, Juno and New Horizons, which have produced incredibly sharp images of Saturn, Jupiter and Pluto, respectively.
"What we've never done is take a spacecraft and place it outside our entire solar system," Jason Calliroy, an astrophysicist at the Johns Hopkins Laboratory of Applied Physics in Maryland, said during the panel.
The sun affects a region around where the Earth, comets, and other planets move. This "bubble" acts as a barrier to prevent dangerous cosmic radiation and to retain the sun-charged particles that are essential for plants and humans. By sending a probe into the interstellar space, scientists could better understand how this bubble is formed and what the bubbles around the other stars may be.
The kinds of questions we can ask about the heliosphere while we are still inside it are subject to a number of different biases, according to Princeton University helicopter Jamie Salai, who was also part of the group. As he put it, an interstellar mission is the "next step of magnitude" after Voyager.
NASA's Voyager 1 and 2 spacecraft, launched in 1977, became the first probes to emerge from the solar system. In August 2012, Voyager 1 reached interstellar space, having noticed that it was surrounded by a 9% increase in galactic cosmic rays coming from outside the solar system. Voyager 2 entered the interstellar space six years later, in November 2018. The incredible duo continues to send back data to Earth and is evidence of multi-generational research.
While still in its infancy, NASA hopes its Space Launch Space Missile (SLS) will take the Interstellar probe to the edge of our fishbowl in less time than Voyager's 35-year voyage 1. According to a panel comment by Rob Stough, SLS usage manager, the next-generation rocket launch capability could support the Interstellar probe and its potential legacy.
Researchers are still deciding where to place the probe in the heliosphere's fish bowl. "We are not sure exactly which direction [to take] we are heading into the interstellar environment," says Michael Paul, head of the John Hopkins Applied Physics Laboratory research study at John Hopkins before Space.com before the panel discussion. "Should we go in the direction that follows the Voyagers, do we go in the direction indicated by the new science that [will] comes from missions like IMAP, which IBEX showed us, will we [or] take a new direction at all? "
" We don't know which direction we're going to go yet … [and] we're open to where we are going to visit on our way out, "Paul adds.
There's still something to decide, but enthusiasm is already there and growing | 0.872553 | 3.617934 |
A mystery has long surrounded the "left-handed"bias in the building blocks of life. Now scientists have confirmed the sameleft-handed bias in meteorites, which may suggest that life on Earth originatedfrom space rocks.
That bias exists in aminoacids, the basic components of proteins, which can come in a left-handed orright-handed configuration. Left-handed or right-handed life can only breakdown and use their respective amino acids, which means that left-handed lifecould have gained an advantage in an Earth environment with more left-handedamino acids.
Researchers examined meteorites dating back more than 4.5billion years, or older than Earth's existenceas a planet, and found that meteorites with the longest exposures to waterwithin had a much stronger left-handed bias.
"We don't have records on Earth, so we look tometeorites," said Daniel Glavin, an astrobiologist at NASA's Goddard SpaceFlight Center in Maryland. "They tell us a very interesting story thatthere was a left-handed bias prior to the emergence of life."
Researchers have known about a left-handedbias on Earth for years, but it first came to light for space rocks in a1997 study of the Murchison meteorite found in Australia. Since then, Glavinand another NASA Goddard astrobiologist examined six meteorites that fit intothree different classifications. Half of the meteorites showed the left-handedbias.
"The two meteorites where we saw the highestleft-handed enrichment had the longest exposure to water," Glavin told SPACE.com.The evidence suggested that the meteorites had been exposed to liquid waterover time periods ranging from 1,000 to 10,000 years.
Glavin added that the most pristine meteorites withlittle water exposure showed no evidence for the left-handed bias, with waterexposure being estimated based on the presence of clays and minerals.
Previous lab experiments have shown that liquid water canamplify any inequality in amino acids, whether a small bias exists towardleft-handed or right-handed types — but a neutral experiment should turn up a50:50 ratio for left-handed and right-handed.
Now the new research provides the first evidence ofwater's effect on amino acids in the natural world, Glavin said. Such liquidwater could have arisen within asteroids when radioactive decay heated andmelted the ice, long before the asteroids fell to Earth as meteorites.
Other effects may have played a role in the left-handedbias within space rocks. For instance, polarized light from neutron stars couldhave selectively destroyed more right-handed molecules as opposed toleft-handed molecules, when the right-handed molecules absorbed more light.
The polarized light may account for a percent or two ofthe imbalance, Glavin noted. But he and Dworkin found around 15 percent moreleft-handed amino acids within some meteorites.
"You would have to destroy too much of the compound[with polarized light]," Glavin said. "That's why we really like theidea of water exposure."
This still leaves the question of what created the smallleft-handed bias in the first place. But the confirmation of water'samplification of the imbalance within meteorites may lend more weight to thenotion that life on Earth camefrom outer space — or at least some space rock in the main asteroid beltbetween Mars and Jupiter.
And that still doesn't mean right-handed life neverexisted on primitive Earth, or doesn't exist elsewhere in the universe.However, all the current evidence suggests that both Earth and the solar systemlean left.
Glavin and Dworkin plan on studying even more meteorites,including samples from hundreds which have turned up in Antarctica. But theirskepticism about the left-handed bias which exists beyond Earth has vanished,after they spent several years ruling out factors such as faulty analyses orpossible contamination of the meteorites.
"We just recently ran out of explanations,"Glavin said. "It's a really rock-solid case." | 0.853801 | 3.779479 |
Now at Ceres, Dawn's camera recorded this closer view of the dwarf planet's northern hemisphere and one of its mysterious bright spots on May 4. A sunlit portrait of a small, dark world about 950 kilometers in diameter, the image is part of a planned sequence taken from the solar-powered spacecraft's 15-day long RC3 mapping orbit at a distance of 13,600 kilometers (8,400 miles). The animated sequence shows Ceres' rotation, its north pole at the top of the frame. Imaged by Hubble in 2004 and then by Dawn as it approached Ceres in 2015, the bright spot itself is revealed to be made up of smaller spots of reflective material that could be exposed ice glinting in the sunlight. On Saturday, Dawn's ion propulsion system was turned on to spiral the spacecraft into a closer 4,350-kilometer orbit by June 6. Of course another unexplored dwarf planet, Pluto, is expecting the arrival of a visitor from Earth, the New Horizons spacecraft, by mid-July.
If you were floating above the Earth right now, this is what you might see. Two weeks ago, the robotic SpaceX Dragon capsule that delivered supplies to the Earth-orbiting International Space Station (ISS) also delivered High Definition Earth Viewing (HDEV) cameras that take and transmit live views of Earth. Pictured above, when working, is the live video feed that switches between four cameras, each pointed differently. Watch white clouds, tan land, and blue oceans drift by. The above video will appear black when it is nighttime on the Earth below, but the space station's rapid 90-minute orbit compresses this dark time into only 45 minutes. The present location of the ISS above the Earth can be found on the web. If the video appears gray, this indicates that the view is either being switched between cameras, or communications with the ISS is temporarily unavailable. As the HDEV project continues, video quality will be monitored to assess the effects of high energy radiation, which types of cameras work best, and which Earth views are the most popular. Although this feed will eventually be terminated, lessons learned will enable better cameras to be deployed to the ISS in the future, likely returning even more interesting live feeds.
Images Credit: NASA, ESA; Visualization: Frank Summers (STScI); Simulation: Chris Mihos (CWRU) & Lars Hernquist (Harvard)
What happens when two galaxies collide? Although it may take over a billion years, such titanic clashes are quite common. Since galaxies are mostly empty space, no internal stars are likely to themselves collide. Rather the gravitation of each galaxy will distort or destroy the other galaxy, and the galaxies may eventually merge to form a single larger galaxy. Expansive gas and dust clouds collide and trigger waves of star formation that complete even during the interaction process. Pictured above is a computer simulation of two large spiral galaxies colliding, interspersed with real still images taken by the Hubble Space Telescope. Our own Milky Way Galaxy has absorbed several smaller galaxies during its existence and is even projected to merge with the larger neighboring Andromeda galaxy in a few billion years.
Images Credit: NASA, JPL-Caltech, UCLA, MPS, DLR, IDA; Animation: German Aerospace Center (DRL)
What would it be like to fly over the asteroid Vesta? Animators from the German Aerospace Center recently took actual images and height data from NASA's Dawn mission currently visiting Vesta to generate such a virtual movie. The above video begins with a sequence above Divalia Fossa, an unusual pair of troughs running parallel over heavily cratered terrain. Next, the virtual spaceship explores Vesta's 60-km Marcia Crater, showing numerous vivid details. Last, Dawn images were digitally recast with exaggerated height to better reveal Vesta's 5-km high mountain Aricia Tholus. Currently, Dawn is rising away from Vesta after being close enough to obtain the most detailed surface images and gravity measurements of the Solar System's second largest asteroid. In August, Dawn is scheduled to blast away from Vesta and head toward Ceres, the Solar System's largest asteroid.
At 2nd magnitude, Polaris is far from the brightest star in the night sky. But it is the brightest star at the left of this well-composed, starry mosaic spanning about 23 degrees across the northern sky asterism dubbed the Little Dipper. Polaris is famous as the North Pole Star, a friend to navigators and astrophotographers alike, but it's not located exactly at the North Celestial Pole (NCP) either. It's presently offset from the NCP by 0.7 degrees. Sliding your cursor over the picture will locate Polaris and the NCP as well as other stars of the Little Dipper. The stars are shown with their proper names preceded by their greek alphabet designations within the ancient constellation Ursa Minor, the Little Bear. Dust clouds suspended above the plane of our Milky Way Galaxy are also faintly visible throughout the wide field of view.
The arc of the southern Milky Way shone brightly on this starry night. Captured on May 4, in the foreground of this gorgeous skyview is the rainforest near the spectacular Iguaçu Falls and national park at the border of Brazil and Argentina. Looking skyward along the Milky Way's arc from the left are Alpha and Beta Centauri, the Coalsack, the Southern Cross, and the Carina Nebula. Sirius, brightest star in planet Earth's night sky is at the far right. Brilliant Canopus, second brightest star in the night, and our neighboring galaxies the Large and Small Magellanic clouds, are also included in the scene. For help finding them, just slide your cursor over the image. Much closer to home, lights near the center along the horizon are from Argentina's Iguazú Falls International Airport.
Normally faint and elusive, the Jellyfish Nebula is caught in this alluring wide-field telescopic view. Flanked by two yellow-tinted stars, Mu and Eta Geminorum, at the foot of a celestial twin, the Jellyfish Nebula is the brighter arcing ridge of emission with dangling tentacles right of center. In fact, the cosmic jellyfish is seen to be part of bubble-shaped supernova remnant IC 443, the expanding debris cloud from a massive star that exploded. Light from the explosion first reached planet Earth over 30,000 years ago. Like its cousin in astrophysical waters the Crab Nebula supernova remnant, IC 443 is known to harbor a neutron star, the remnant of the collapsed stellar core. Emission nebula Sharpless 249 fills the field at the upper left. The Jellyfish Nebula is about 5,000 light-years away. At that distance, this image would be almost 200 light-years across.
Looking out a window of the International Space Station brings breathtaking views. Visible vistas include a vast and colorful Earth, a deep dark sky, and an occasional spaceship sent to visit the station. Visible early last month was a Soyuz TMA-12 spacecraft carrying not only supplies but also three newcomers. The three new astronauts were Expedition 17 commander Sergei Volkov, flight engineer Oleg Kononenko, and spaceflight participant So-yeon Yi. Yi returned to Earth a few days later, while Volkov and Konenenko are scheduled to return in a few months. The docking module pictured above involved the Pirs Docking Compartment. The Expedition 17 crew, including NASA flight engineer Gregory Chamitoff, will carry out repairs on the ISS, explore new methods of living in space, and conduct research in space including the effects of space radiation on vitamin molecules.
When passing Earth on your way to Jupiter, what should you look for? That question arose for the robotic Galileo spacecraft that soundlessly coasted past the Solar System's most photographed orb almost two decades ago. The Galileo spacecraft, although originally launched from Earth, coasted past its home world twice in an effort to gain speed and shorten the duration of its trip to Jupiter. During Galileo's first Earth flyby in late 1990, it made a majestically silent home movie of our big blue marble rotating by taking images almost every minute during a 25-hour period. The above picture is one frame from this movie -- clicking on this frame will put it in motion (in many browsers). Visible on Earth are vast blue oceans, swirling white clouds, large golden continents, and even one continent frozen into a white sheet of water-ice. As Galileo passed, it saw a globe that not only rotated but began to recede into the distance. Galileo went on to a historic mission uncovering many secrets and mysteries of Jupiter over the next 14 years, before performing a final spectacular dive into the Jovian atmosphere.
The most photogenic array of radio telescopes in the world has also been one of the most productive. Each of the 27 radio telescopes in the Very Large Array (VLA) is the size of a house and can be moved on train tracks. The above pictured VLA, inaugurated in 1980 is situated in New Mexico, USA. The VLA has been used to discover water on planet Mercury, radio-bright coronae around ordinary stars, micro-quasars in our Galaxy, gravitationally-induced Einstein rings around distant galaxies, and radio counterparts to cosmologically distant gamma-ray bursts. The vast size of the VLA has allowed astronomers to study the details of super-fast cosmic jets, and even map the center of our Galaxy. An upgrade of the VLA is being planned.
Similar in size and grand design to our own Milky Way, spiral galaxy NGC 3370 lies about 100 million light-years away toward the constellation Leo. Recorded here in exquisite detail by the Hubble Space Telescope's Advanced Camera for Surveys, the big, beautiful face-on spiral does steal the show, but the sharp image also reveals an impressive array of background galaxies in the field, strewn across the more distant Universe. Looking within NGC 3370, the image data has proved sharp enough to study individual pulsating stars known as Cepheids which can be used to accurately determine this galaxy's distance. NGC 3370 was chosen for this study because in 1994 the spiral galaxy was also home to a well studied stellar explosion -- a type Ia supernova. Combining the known distance to this standard candle supernova, based on the Cepheid measurements, with observations of supernovae at even greater distances, can reveal the size and expansion rate of the Universe itself.
Moderately bright Zubenelgenubi is the star just off the upper right hand limb of an eclipsed Moon in this telescopic view from Port Elizabeth, South Africa. Actually the second brightest star in the constellation Libra, Zubenelgenubi is fun to pronounce (try zoo-BEN-al-je-NEW-bee ...) and rewarding to spot in the night sky as it has a fainter companion star, seen here on the far right. Astronomer Francois du Toit reports that both stars were visible to the unaided eye on the night of May 4th, during the Moon's total eclipse phase. Orbiting a common center of gravity once every 200,000 years or so, the two stars are both larger and hotter than the Sun. About 77 light years away they are separated from each other by over 730 light hours -- about 140 times Pluto's average distance from the Sun. Zubenelgenubi was once considered the southern claw of the nearby arachnologically correct constellation Scorpius. What star was the northern claw? Zubeneschamali, of course.
If you could look down on the North Pole of Venus what would you see? The Magellan probe that orbited Venus from 1990 to 1994 was able to peer through the thick Venusian clouds and build up the above image by emitting and re-detecting cloud-penetrating radar. Visible as the bright patch below central North is Venus' highest mountain Maxwell Montes. Other notable features include numerous mountains, coronas, impact craters, tessera, ridges, and lava flows. Although the size and mass of Venus are similar to the Earth, its thick carbon-dioxide atmosphere has trapped heat so efficiently that surface temperature usually exceeds 700 kelvins, hot enough to melt lead.
Why is N44C glowing so strangely? The star that appears to power the nebula, although young and bright, does not seem hot enough to create some of the colors observed. A search for a hidden hotter star in X-rays has come up empty. One hypothesis is that the known central star has a neutron star companion in a very wide orbit. Hot X-rays might only then be emitted during brief periods when the neutron star nears the known star and crashes through a disk of surrounding gas. Future observations might tell. N44C, pictured in the above Hubble Space Telescope image, is an emission nebula in the Large Magellanic Cloud, a neighboring galaxy to our Milky Way Galaxy. Flowing filaments of colorful gas and dark dust far from the brightest region are likely part of the greater N44 complex. It would take light about 125 years to cross N44C.
High atop a Chilean mountain lies one of the premier observatories of the southern sky: Cerro Tololo. Pictured above is one of the premier telescopes of the Cerro Tololo Inter-American Observatory (CTIO) and of the past quarter-century: the 4-meter Blanco Telescope. Far behind the telescope are thousands of individual stars and diffuse light from three galaxies: the Small Magellanic Cloud (upper left), the Large Magellanic Cloud (lower left), and our Milky Way Galaxy (right). Visible just to Blanco's right is the famous superposition of four bright stars known as the Southern Cross. The observatory structures are lit solely by starlight.
Scroll right to unfold one of the great panoramas ever taken on the surface of Mars. For best viewing, click and hold the right arrow icon at the bottom of your browser window. This image, dubbed a "presidential panorama" by the Mars Pathfinder team, shows in colorful detail the surroundings of the Sagan Memorial Station. Now look closely at the big rock midway through the scrolling picture. That rock is called Yogi and just to its left is the robot Sojourner Rover taking measurements of it. Other now-famous rocks are also visible including Barnacle Bill and Flat Top. After this picture was taken Sojourner went on to analyze a rock named Scooby Doo. The Mars Pathfinder mission landed on 1997 July 4 and collected data for about three months. Analysis indicates that the Pathfinder site was likely awash in water in the distant past, but has been dry for the last two billion years.
Launched last month, NASA's Landsat 7 spacecraft now orbits planet Earth. Looking down from an altitude of 700 km, Landsat 7 can map the planet's surface in visible and infrared bands and resolve features 30 meters across or smaller. For example, this striking engineering test image is a natural-looking color composite of 3 different visible wavelength bands. It nicely shows details of urban areas around San Francisco, California, USA, nestled in the surrounding terrain (north is up). Flowing blue-green colors track the spring runoff from the Sierras to the west and neighboring mountains into the bay and out into the Pacific ocean. Landsat 7 is currently performing well in its check out phase and controllers are preparing the satellite for regular operations.
Comets move against a field of background stars. Their apparent motion is slow but carefull tracking reveals their orbits, allowing these visitors to the inner solar system to be identified as old or new acquaintances. Recently a new comet, designated 1998 H1, was discovered by observer Patrick L. Stonehouse of Wolverine, Michigan, USA, and announced on April 26. At 10th magnitude, comet Stonehouse is too faint to be seen by the unaided eye, but it is presently a popular object for telescope-equipped comet watchers. This false color picture of comet Stonehouse was taken on May 1st at Limber Observatory and is a composite of 8 exposures each 60 seconds long. The sequence of exposures was made with the telescope following the background stars. The individual pictures were then aligned on the comet and added together. Because of the comet's relative motion, the combined multiple-exposure shows trails of progressively offset star images but nicely captures the comet's coma and faint, tenuous tail.
What's happening to Comet Hale-Bopp's blue ion tail? The comet's ion tail is fluctuating more rapidly as it passes a region of changing solar wind. As the comet passes from north to south, it crosses the plane of the Sun's equator, where the solar magnetic field changes direction. Ions from the solar wind, which cause Comet Hale-Bopp's ion tail, act unpredictably here. Therefore, Comet Hale-Bopp's ion tale may show unusual structure or even a disconnection - where the tail appears to break off and then reestablish itself later. The above picture, taken April 30th, indeed shows unusual structure in the blue ion tail.
In this century, the discovery that the Universe is expanding has produced a revolution in human thought about the Cosmos. American astronomer Edwin Hubble played a major role in this profound discovery, coining the "Hubble constant". This single number describes the rate of the cosmic expansion, relating the apparent recession velocities of external galaxies to their distance. Two groups of astronomers trying to measure this fundamental constant using the Hubble Space Telescope (HST) are continuing to report conflicting results. One group, led by astronomer Allan Sandage, measures distances to galaxies using pulsating Cepheid variable stars and supernovae observed in galaxies like the Virgo Cluster spiral galaxy, NGC4639, shown above. This galaxy is the most distant one to which Cepheid-based determinations have been made and was also the site of a well-studied 1990 supernova. Their results favor a relatively small Hubble constant (slow expansion rate) of about 55 kilometers per second per megaparsec which means that galaxies one megaparsec (3 million lightyears) distant appear to recede from us at a speed of 55 kilometers per second. A substantially faster expansion rate (larger Hubble constant) is being reported by astronomer Wendy Freedman and collaborators, also based on HST data. The value of Hubble's constant was recently the subject of a popular public debate titled "The Scale of the Universe 1996: The Value of Hubble's Constant". | 0.946655 | 3.636538 |
Crescent ♑ Capricorn
Moon phase on 13 December 2015 Sunday is Waxing Crescent, 2 days young Moon is in Capricorn.Share this page: twitter facebook linkedin
Previous main lunar phase is the New Moon before 2 days on 11 December 2015 at 10:29.
Moon rises in the morning and sets in the evening. It is visible toward the southwest in early evening.
Moon is passing about ∠16° of ♑ Capricorn tropical zodiac sector.
Lunar disc appears visually 3.8% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1876" and ∠1949".
Next Full Moon is the Cold Moon of December 2015 after 11 days on 25 December 2015 at 11:11.
There is low ocean tide on this date. Sun and Moon gravitational forces are not aligned, but meet at big angle, so their combined tidal force is weak.
The Moon is 2 days young. Earth's natural satellite is moving from the beginning to the first part of current synodic month. This is lunation 197 of Meeus index or 1150 from Brown series.
Length of current 197 lunation is 29 days, 15 hours and 1 minute. It is 1 hour and 53 minutes longer than next lunation 198 length.
Length of current synodic month is 2 hours and 17 minutes longer than the mean length of synodic month, but it is still 4 hours and 46 minutes shorter, compared to 21st century longest.
This lunation true anomaly is ∠255.6°. At the beginning of next synodic month true anomaly will be ∠292.2°. The length of upcoming synodic months will keep decreasing since the true anomaly gets closer to the value of New Moon at point of perigee (∠0° or ∠360°).
7 days after point of apogee on 5 December 2015 at 14:56 in ♎ Libra. The lunar orbit is getting closer, while the Moon is moving inward the Earth. It will keep this direction for the next 7 days, until it get to the point of next perigee on 21 December 2015 at 08:53 in ♉ Taurus.
Moon is 382 020 km (237 376 mi) away from Earth on this date. Moon moves closer next 7 days until perigee, when Earth-Moon distance will reach 368 418 km (228 924 mi).
8 days after its ascending node on 4 December 2015 at 18:33 in ♍ Virgo, the Moon is following the northern part of its orbit for the next 5 days, until it will cross the ecliptic from North to South in descending node on 18 December 2015 at 15:13 in ♓ Pisces.
8 days after beginning of current draconic month in ♍ Virgo, the Moon is moving from the beginning to the first part of it.
1 day after previous South standstill on 12 December 2015 at 08:15 in ♑ Capricorn, when Moon has reached southern declination of ∠-18.438°. Next 11 days the lunar orbit moves northward to face North declination of ∠18.444° in the next northern standstill on 25 December 2015 at 07:30 in ♋ Cancer.
After 11 days on 25 December 2015 at 11:11 in ♋ Cancer, the Moon will be in Full Moon geocentric opposition with the Sun and this alignment forms next Sun-Earth-Moon syzygy. | 0.848363 | 3.101359 |
The ASTERIA satellite, which was deployed into low-Earth orbit in November, is only slightly larger than a box of cereal, but it could be used to help astrophysicists study planets orbiting other stars.
Mission managers at NASA's Jet Propulsion Laboratory in Pasadena, California, recently announced that ASTERIA has accomplished all of its primary mission objectives, demonstrating that the miniaturized technologies on board can operate in space as expected. This marks the success of one of the world's first astrophysics CubeSat missions, and shows that small, low-cost satellites could be used to assist in future studies of the universe beyond the solar system.
"ASTERIA is small but mighty," said Mission Manager Matthew W. Smith of JPL. "Packing the capabilities of a much larger spacecraft into a small footprint was a challenge, but in the end we demonstrated cutting-edge performance for a system this size."
ASTERIA, or the Arcsecond Space Telescope Enabling Research in Astrophysics, weighs only 22 pounds (10 kilograms). It carries a payload for measuring the brightness of stars, which allows researchers to monitor nearby stars for orbiting exoplanets that cause a brief drop in brightness as they block the starlight.
This approach to finding and studying exoplanets is called the transit method. NASA's Kepler Space Telescope has detected more than 2,300 confirmed planets using this method, more than any other planet-hunting observatory. The agency's next large-scale, space-based planet-hunting observatory, the Transiting Exoplanet Survey Satellite (TESS), is anticipated to discover thousands of exoplanets and scheduled to launch from Cape Canaveral Air Force Station in Florida on April 16.
In the future, small satellites like ASTERIA could serve as a low-cost method to identify transiting exoplanets orbiting bright, Sun-like stars. These small satellites could be used to look for planetary transits when larger observatories are not available, and planets of interest could then be studied in more detail by other telescopes. Small satellites like ASTERIA could also be used to study certain star systems that are not within the field of view of larger observatories, and most significantly, focus on star systems that have planets with long orbits that require long observation campaigns.
The ASTERIA team has now demonstrated that the satellite's payload can point directly and steadily at a bright source for an extended period of time, a key requirement for performing the precision photometry necessary to study exoplanets via the transit method.
Holding steady on a faraway star is difficult because there are many things that subtly push and pull on the satellite, such as Earth's atmosphere and magnetic field. ASTERIA's payload achieved a pointing stability of 0.5 arcseconds RMS, which refers to the degree to which the payload wobbles away from its intended target over a 20-minute observation period. The pointing stability was repeated over multiple orbits, with the stars positioned on the same pixels on each orbit.
"That's like being able to hit a quarter with a laser pointer from about a mile away," said Christopher Pong, the attitude and pointing control engineer for ASTERIA at JPL. "The laser beam has to stay inside the edge of the quarter, and then the satellite has to be able to hit that exact same quarter – or star – over multiple orbits around the Earth. So what we've accomplished is both stability and repeatability."
The payload also employed a control system to reduce "noise" in the data created by temperature fluctuations in the satellite, another major hurdle for an instrument attempting to carefully monitor stellar brightness. During observations, the temperature of the controlled section of the detector fluctuates by less than 0.02 Fahrenheit (0.01 Kelvin, or 0.01 degree Celsius).
ASTERIA is a CubeSat, a type of small satellite consisting of "units" that are 10 centimeters cubed, or about 4 inches on each side. ASTERIA is the size of six CubeSat units, making it roughly 10 centimeters by 20 centimeters by 30 centimeters. With its two solar panels unfolded, the satellite is about as long as a skateboard.
The ASTERIA mission utilized commercially available CubeSat hardware where possible, and is contributing to a general knowledge of how those components operate in space.
"We're continuing to characterize CubeSat components that other missions are using or want to use," said Amanda Donner, mission assurance manager for ASTERIA at JPL.
ASTERIA launched to the International Space Station in August 2017. Having been in space for more than 140 days, the satellite is operating on an extended mission through May.
ASTERIA was developed under the Phaeton Program at JPL. Phaeton provides early-career hires, under the guidance of experienced mentors, with the challenges of a flight project. ASTERIA is a collaboration with the Massachusetts Institute of Technology in Cambridge; where Sara Seager is the principal investigator. | 0.839689 | 3.852362 |
Look closely at the galaxies in the above photo. They look bizarre, don't they? These galaxies aren't just bizarre, they are 60 times brighter in the infrared spectrum than they are in the reddest colors that the Hubble Space Telescope can detect. In fact, these galaxies are so strange that they are actually a whole new morphological classification--the system used by scientists to class galaxies based on visual appearance--of galaxy.
Deep in the cosmos--nearly 13 billion light-years from Earth--lay galaxies that are so far into the red part of the spectrum that the most powerful visible-light telescope--the Hubble--can't even see them. These galaxies are so far into the infrared range that it took the Spitzer Space Telescope, a powerful infrared space observatory, to stumble upon them.
How Red Is Red?
The human eye can see electromagnetic waves in the spectral range that lie between 380 and 760nm (nanometers), in what's also known as the visible light range. The Hubble can "see" waves between 115 and 1030nm (from ultraviolet to the tip of the near-infrared spectrum), and the Spitzer can see from 3000 to 180,000nm (from mid-infrared through far-infrared and up to terahertz radiation on the edge of the microwave band).
The galaxies are actually so red in fact that the researchers "had to go to extremes to get the models to match our observations," according to Jiasheng Huang of the Harvard-Smithsonian Center for Astrophysics (CfA).
Plenty of Possibilities, But No Answers
According to the Harvard-Smithsonian Center for Astrophysics--a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory--the galaxies can be this red for a number of reasons. For starters, the galaxies may be simply so far away that a process called redshifting may cause them to appear red due to the expansion of the universe. That is, the galaxies may be moving away from Earth, which would cause the wavelengths of the light given off to become longer (and therefore more red).
Alternatively, the galaxies could be filled with old red giant stars that are near their deathbed, or the galaxies might be very dusty and obscuring the visual range waves from Hubble.
The researchers found four of these odd-looking galaxies close together (in the astronomical scheme of things, anyway), and they believe that there may be more of them. The researchers plan to use the Spitzer observatory to find more of these sorts of galaxies.
When more powerful instruments--like the Atacama Large Millimeter Array--are ready to use, astronomers plan to measure the redshift to determine if that's why they are so red. If it isn't just a case of redshift, then these galaxies will become an even greater mystery. "Hubble has shown us some of the first protogalaxies that formed, but nothing that looks like this," says co-author Giovanni Fazio of the CfA.
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Astronomers across the globe were quick to begin studying 2I/Borisov – the second known interstellar object to visit our solar system – almost immediately upon its detection in August.
Those observations are already yielding fascinating insights into the comet – including the fact that its solar system of origin might not be that different from our own.
An Institute of Astrophysics of the Canary Islands study published in the non-peer-reviewed journal Research Notes of the AAS found that the dust emitted by 2I/Borisov is similar in composition to that of comets originating from our own solar system.
Another study – this one conducted by researchers from Queen’s University Belfast and published on the preprint server arXiv – determined that the gas surrounding the interstellar object is similar to that of our own comets.
“And when we look at the amount of gas we see, compared to the amount of dust particles that the comet is also ejecting, it looks pretty similar as well,” researcher Alan Fitzsimmons told Scientific American.
While researchers can’t yet say for certain whether 2I/Borisov’s home is like ours or not, they’re excited by either prospect.
“If it’s like the things that we have in our solar system, the processes that we see taking place are more typical than we realized,” Queen’s University Belfast researcher Michele Bannister told SA. “If it’s really different, then that tells us this chemistry takes place in quite a different way – in the diversity of exoplanetary systems – than we see.” | 0.86083 | 3.430789 |
This story was updated with details of the 2018 lunar eclipse.
Have you ever stared at a rising full moon and felt the crushing realization of how small and alone you are in the universe? Just wait a few hours, and you might feel a little less small.
If you’ve ever noticed that the moon seems bigger when it’s rising than when it’s high up in the sky, NASA has an easy way to prove that’s just an illusion. And with this week bringing the 21st century’s longest lunar eclipse, now’s a good time to try.
We can blame our brains for tricking us into seeing the moon as more round and full when it’s rising. NASA suggests a DIY test to demonstrate that it’s all just a game our minds are playing on us.
First, photograph the moon as it starts rising just above a distant horizon. Then, photograph it again a couple of hours later (NASA advises using a camera with a long telephoto lens). Although the lower moon might look a bit more squashed, when you measure the horizontal diameters of the two moons, they will be the same. Writes NASA:
The squashed-looking Moon will also have a much warmer tint than the high Moon. This is due to the low Moon’s light passing through more of Earth’s atmosphere than the high Moon’s light. That squashed look is due to Earth’s atmosphere behaving like a weak lens with moonlight being bent more near the horizon than it is slightly higher above the horizon.
Ideally, you can use a tripod and cable release to capture your pictures, and NASA has other tips for taking the best pictures, including suggestions on shutter speeds and exposure bracketing. You can try this nifty test out with any full moon, or for the next two supermoons happening in January.
If you don’t have a camera, you can do the same test with a rolled sheet of paper, following these instructions from Sky and Telescope. | 0.813434 | 3.191396 |
I am endlessly amused by image and/or press releases. I get a lot of them (as a professional science communicator I subscribe to quite a few mailing lists), and it’s interesting to see how they frame the news. Sometimes, it’s a big discovery. Sometimes, it’s a bit of news about progress on a piece of equipment or mission. And, sometimes, it’s just a tidbit about a pretty picture.
I’m all for that last; a pretty picture is, well, pretty, but it can also be used to talk about some fun science in addition to serving as a bit of eye candy. Beauty and science often intertwine, so using a cool photo as an attention grabber to open a pathway to even a somewhat deeper understanding is fine by me. But I’m sometimes tickled by the choices made in the releases.
For example: The good folks at the European Space Agency just released a gorgeous photo of a nearby spiral galaxy taken by Hubble. Feast your eyes on this:
Wow! That’s NGC 4536, a galaxy 48 million light years away and roughly the same size as our Milky Way. It’s near the huge Virgo Cluster of galaxies, a collection of well over a thousand galaxies about 50 million light years away. NGC 4536 may not be a part of the main cluster, but instead dwells in a subgroup of it called the M61 group a bit to the south.
The image isn’t “true color” as such; it’s a combination of light seen through a green filter (displayed as blue), and a near infrared filter (displayed as red). That skews the colors a bit. For example, big clouds of gas tend to emit strongly in red light, and that’s difficult to see here, since the filters used select for colors other than that one. Still, it’s a lovely shot.
Anyway, the release talks about how NGC 4536 is what we call a “starburst” galaxy: one that is undergoing an intense episode of star formation. We see quite a few galaxies like this; sometimes that’s due to a collision with another galaxy. When that happens the gas clouds slam into each other, collapse, and form stars rapidly (and by that, I mean over some millions of years). A galaxy like that can produce stars at many times the rate of a normal galaxy.
That’s very cool, and I was happy to do a little digging to find out more about it, but during my reading, I had to chuckle. One of the first things I did was to look at the listing for the Hubble observations, themselves. NGC 4536 has been a target for Hubble many times, but in this particular case, it was observed using the Wide Field Camera 3 in 2010. Why? Well, that’s the funny thing. It wasn’t observed because it’s a starburst galaxy; it was observed because it was the host to a star that exploded!
In 1981, the light from that supernova reached us. It was a Type Ia, a very special kind of explosion. For details, watch my Crash Course Astronomy episode about them, but in a nutshell we think these explosions all give off the same amount of energy (or can be calibrated in various ways to put them all on equal footing). Because of that, they can be used as distance markers! If we see one that looks fainter, it must be farther away than a brighter Type Ia explosion.
A very important piece of this is to find nearby Type Ia supernovae, so we can use other methods to find their distance as accurately as possible. If one occurs in a nearby galaxy, there are several processes we can employ to get their distance. These don’t work for galaxies farther away (they’re too faint), but if a distant galaxy hosts a Type Ia supernova we can use what we’ve learned from ones in nearby galaxies to extrapolate the distance to that farther one.
Supernovae can be seen from billions of light years, and so if we can measure their distance, we can measure how the Universe itself behaves on vast scales. For example, we know the Universe is expanding. But by measuring the light from very distant Type Ia supernovae, two different teams of astronomers discovered that the expansion rate of the Universe, itself, is increasing. The cosmos is accelerating!
And that’s why NGC 4536 was observed. Hubble can see fainter stars in nearby galaxies than other telescopes, so it was used to look for others kinds of stars that can serve to get the galaxy’s distance (the kind in this case are called Cepheid variables, which are a tried-and-true distance marker). Once the distance to NGC 4536 is found using those, then the Type Ia supernova we saw in that galaxy in 1981 can be used to measure even farther distances. NGC 4536 is one rung on the distance ladder, a way we can go from getting distances of nearby stars out to the vast depths of the entire Universe.
Mind you, I am not in any way trying to put down the release for this image! It’s quite good, and fun to read. The fact that NGC 4536 is a starburst is interesting, and a fine bit of info to discuss when showing the Hubble image of the galaxy. But I found it mildly amusing that the reason the observations were made in the first place is also interesting, and worth explaining.
I guess that’s a problem when you’re trying to communicate science. Which avenue do you explore? A galaxy is hardly ever just a galaxy. It’s a huge community of stars, gas, dust, dark matter, and all sorts of science that makes it wonderfully rich and fascinating. Sometimes you just have to pick one thing and go with it.
Hmmmm, maybe I was wrong. That’s not a problem at all! Or, if it is, then it’s a good one to have.
Correction, April 24, 2017: I originally attributed Jennie Hottle in creating this picture from Hubble images, but that was an error on my part. | 0.815216 | 3.361923 |
What causes seasons? The distance between the Earth and the Sun does not account for the seasons. Look at page xii in Goodes World Atlas. First, you will note that the earth’s orbit is indeed not quite circular. The distance between the sun and the earth on the winter solstice (December 22) is 91.5 million miles, while the distance between the sun and the earth on the summer solstice is a whopping 94.5 million miles. So the earth is actually closer to the sun in December than it is in June! Click on the image thumbnail below to see a full-size image of Spreading Sunlight Over the Spherical Earth.
Figure 1.6.1 Earth - Sun Relationships and Solar Energy
The earth is tilted 23.5 degrees off of vertical, and this tilt accounts for the seasons. Insolation is distributed over the (nearly) spherical earth. The sunlight is most concentrated at the point where the ray of the sun is perpendicular to the tangent of the earth. As the angle between the sun’s rays and the tangent becomes smaller, the effect is that the same amount of sun energy is spread over a larger area. Or, each area gets less energy. The graphic below is another way to visualize this concept:
Figure 1.6.2 Solar energy spread over earth's surface
The seasons are caused not by distance from the sun, but by the effect of the uneven distribution of sunlight on the tilted earth. The earth rotates around the sun on a flat plane. This is called the plane of the ecliptic. The earth is tilted 23.5 degrees off of this plane. The tilt does not change, a concept called axial parallelism. In other words, the axis of the earth is parallel to itself throughout the orbit.
You can see in the diagram below (Earth Sun relationships and Incoming Solar Energy) that at the December solstice, the majority of the incoming solar energy is in the Southern Hemisphere, and in June, the majority of the incoming solar energy is in the northern hemisphere. That is because on the December solstice, the sun’s rays are perpendicular to the earth at 23.5 degrees South. This is the subsolar point, or the point of maximum insolation. On the June solstice, the subsolar point is at 23.5 degrees north (see the graphic below). The subsolar points at the solstices define the Tropics. The Tropic of Cancer is 23.5 degrees North, and the Tropic of Capricorn is 23.5 degrees South. At this point it is worth pointing out that while the northern hemisphere experiences summer in June, the southern hemisphere experiences summer in December. Another way to think about it is that the southern hemisphere is ‘in reverse’ of our seasons in the northern hemisphere.
Figure 1.6.3: (left) Summer in Northern Hemisphere. (rigth) Summer in Southern Hemisphere
The next piece of the puzzle is the Circle of illumination. At any time, half of the earth is illuminated by our sun. If the earth had no tilt, this would mean that we could have 12 hours of daylight and 12 hours of darkness everywhere on earth all the time, and as there would be no shift in the subsolar point, we would not have seasons. As I am sure you are aware, this is not the case! If you have every traveled anyplace very far north in the summertime, for example, you may have noted the very long days. I vividly recall sitting in a garden pub while I was in graduate school in England (at about 53 degrees N) and enjoying the sunset at 10PM! The circle of illumination defines the Arctic Circle and the Antarctic circle (see below). How long are the days in the Arctic Circle in June? How long are the days in the Antarctic Circle in June? Why?
Figure 1.6.5: (left) The circle of Illumination Northern Hemisphere. (right) The circle of Illumination Southern Hemisphere
The equinoxes occur in March and September. I like to think of them as 'equal equinoxes' -- in other words, at the equinox the subsolar point is at the equator and the circle of illumination is distributed equally over the earth. In the Earth Sun Relationships diagram above you can see for yourself that the insolation is pretty much equally distributed over the northern and southern hemispheres. Visualize what the circle of illumination looks like at the equinoxes. How long are the days at various latitudes at the equinoxes?
To review key points:
- The Earth's tilted axis (23.5 degrees) causes some parts of the Earth to receive direct sunlight while other parts are receiving indirect sunlight.
- Seasons occur due to the tilt of the Earth's axis and the orbit of the Earth around the Sun.
- The seasons of the Northern and Southern Hemispheres are reversed: when the Northern Hemisphere is experiencing winter, the Southern Hemisphere is experiencing summer.
- The vernal equinox: the first day of spring in the Northern Hemisphere (March 21), when the Sun is perpendicular to the equator.
- The summer solstice: first day of summer in the Northern Hemisphere (June 21), when the Sun is perpendicular to the tropic of Cancer.
- The autumnal equinox: first day of autumn in the Northern Hemisphere (September 22), when the Sun is perpendicular to the equator.
- The winter solstice: first day of winter in the Northern Hemisphere (December 21), when the Sun is perpendicular to the Tropic of Capricorn.
- Key terms: plane of the ecliptic, axial parallelism, circle of illumination, subsolar point.
K. Allison Lenkeit-Meezan (Foothill College) | 0.813862 | 3.601995 |
Quasar jets confuse orbital telescope
Astrophysicists from the Moscow Institute of Physics and Technology, the Lebedev Physical Institute of the Russian Academy of Sciences (LPI RAS), and NASA have found an error in the coordinates of active galactic nuclei measured by the Gaia space telescope, and helped correct it. The findings, published in The Astrophysical Journal, also serve as an independent confirmation of the astrophysical model of these objects.
"One of the key results of our work is a new and fairly unexpected way of indirectly studying the optical emission from the central regions of active galactic nuclei. There is a lot that direct optical observations cannot show us. But radio telescopes proved useful in complementing the picture," commented Alexander Plavin, a researcher at MIPT's relativistic astrophysics lab and a doctoral student at LPI RAS.
While the precision of the coordinates obtained by Earth-based optical telescopes is quite limited, orbital observatories such as Gaia offer a way around this. Launched in 2013, it receives signals from relatively remote cosmic sources and retrieves their coordinates with a superior precision.
Before Gaia, the most precise coordinates were measured by radio telescope arrays (figure 1). These are systems of telescopes that can pick up a low-frequency signal—that is, radio waves—with a decent resolution. That way rather detailed images can be produced, but the objects' positions in space are determined with somewhat less precision than that of Gaia.
The MIPT-LPI team found that for all its precision, Gaia is not infallible. A comparison between the data from Gaia and radio telescopes (for example, figures 2 and 3) revealed a systematic error in the orbital observatory's measurements of an entire class of celestial objects, called active galactic nuclei. As a result, the most accurate space maps are those that rely on orbital observations backed by Earth-based telescopes that provide radio data to enable coordinate correction.
An active galactic nucleus is a compact and very bright region at the center of a galaxy. The emission spectra of AGNs differ from those of the stars, which raises the question about the nature of the object at the center. The current consensus is that AGNs harbor black holes absorbing the matter of their host galaxies. In addition to the galactic disk, its bright nucleus, and the dust cloud around it, such systems can include powerful outflows of matter known as jets. Depending on the nature of the jet, an AGN may be classified as a quasar, a blazar, or otherwise.
Yuri Kovalev, who heads the astrophysics labs at MIPT and LPI RAS, said, "We hypothesized that the jet may be responsible for the systematic error in the coordinates of the active galactic nuclei measured by Gaia. This indeed proved to be the case. It turned out that if an object has a sufficiently long jet, Gaia perceives the source to be much farther along the jet direction than the radio telescopes."
The effect cannot be written off as random, because the offset was in the direction of the jet, and a statistically significant error was only observed for the AGNs with the longest tails. Namely, those whose jets were orders of magnitude larger than the size of the galaxies themselves. The magnitude of the offset was comparable to the length of the jets.
Since last year, Gaia has also been providing information on the visible "colors" of the galaxies. This has enabled the researchers to determine the individual coordinates and contributions to the emission spectrum of the various parts of the galaxy: the source, disk, jet and stars. The coordinate shifts proved to be primarily due to the jets being long and the accretion disks being small. That said, measuring stellar emission has almost no effect on the precision with which the position of a galaxy is determined.
These findings led the authors to conclude that astrophysical effects related to long jets are capable of confusing the Gaia orbital observatory. This means that it cannot be regarded as a fully credible independent source of data on quasar coordinates. To obtain better data, the space telescope needs to be backed with ground-based radio observations (figure 3).
"In the future, by combining observation results, we can see the structure of the central disk-jet system in a quasar in minute detail—with subparsec resolution [where a parsec is an astronomical unit of distance equal to about 3 ¼ light years]. Direct optical telescope observations yield no such images, yet we can get them!" Plavin added.
The findings are independent evidence in support of the unified AGN model. It explains the behavior of the various kinds of AGNs in terms of their orientation in space relative to the observer, rather than in terms of their inner workings.
Being able to precisely measure the positions of celestial objects outside our galaxy is important from a practical standpoint: It is their positions that serve as the best reference for the most punctual coordinate systems, including those underlying GPS and its Russian counterpart GLONASS. | 0.912412 | 4.113204 |
On a Hunt for a Ghost of a Particle
Even for a particle physicist, Janet Conrad thinks small. Early in her career, when her peers were fanning out in search of the top quark, now known to be the heaviest elementary particle, she broke ranks to seek out the neutrino, the lightest.
In part, she did this to avoid working as part of a large collaboration, demonstrating an independent streak shared by the particles she studies. Neutrinos eschew the strong and electromagnetic forces, maintaining only the most tenuous of ties to the rest of the universe through the weak force and gravity. This aloofness makes neutrinos hard to study, but it also allows them to serve as potential indicators of forces or particles entirely new to physics, according to Conrad, a professor at the Massachusetts Institute of Technology. “If there’s a force out there we haven’t seen, it must be because it is very, very weak — very quiet. So looking at a place where things are only whispering is a good idea.”
In fact, neutrinos have already hinted at the existence of a new type of whispery particle. Neutrinos come in three flavors, morphing from one flavor to another by means of some quantum jujitsu. In 1995, the Liquid Scintillator Neutrino Detector (LSND) at Los Alamos National Laboratory suggested that these oscillations involve more than the three flavors “we knew and loved,” Conrad said. Could there be another, more elusive type of “sterile” neutrino that can’t feel even the weak force? Conrad has been trying to find out ever since, and she expects to get the latest result from a long-running follow-up experiment called MiniBooNE within a year.
Still, even MiniBooNE is unlikely to settle the question, especially since a number of other experiments have found no signs of sterile neutrinos. So Conrad is designing what she hopes will be a decisive test using — naturally — a small particle accelerator called a cyclotron rather than a behemoth like the Large Hadron Collider in Europe. “I feel like my field just keeps deciding to get at our problems by growing, and I think that there’s going to be a point at which that’s not sustainable,” Conrad said. “When the great meteor hits, I want to be a small, fuzzy mammal. That’s my plan: small, fuzzy mammal.”
Quanta Magazine spoke with Conrad about her hunt for sterile neutrinos, her penchant for anthropomorphizing particles, and her work on the latest Ghostbusters reboot. An edited and condensed version of the interview follows.
QUANTA MAGAZINE: What would it mean for physics if sterile neutrinos exist?
JANET CONRAD: The Standard Model of particle physics has done very well in predicting what’s going on, but there’s a great deal it can’t explain — for example, dark matter. Right now we’re desperately looking for clues as to what the larger theory would be. We have been working on ideas, and in many of these “grand unified theories,” you actually get sterile neutrinos falling out of the theory. If we were to discover that there were these extra neutrinos, it would be huge. It would really be a major clue to what the larger theory would be.
You’ve been looking for neutrinos your entire career. Was that always the plan?
I started out thinking I was going to be an astronomer. I went to Swarthmore College and discovered that astronomy is cold and dark. I was lucky enough to get hired to work in a particle physics lab. I worked for the Harvard Cyclotron, which was at that time treating eye cancers. But in the evenings physicists would bring their detectors down and calibrate them using the same accelerator. I was really interested in what they were doing and got a position the next summer at Fermilab. It was such a good fit for me. I just think the idea of creating these tiny little universes is so wondrous. Every collision is a little world. And the detectors are really big and fun to work on — I like to climb around stuff. I liked the juxtaposition of the scales; this incredibly tiny little world you create and this enormous detector you see it in.
And how did you get into neutrino research in particular?
When I was in grad school, the big question was: What is the mass of the top quark? Everybody expected me to join one of the collider experiments to find the top quark and measure its mass, and instead I was looking around and was quite interested in what was going on in the neutrino world. I actually had some senior people tell me it would be the end of my career.
Why did you take that risk?
I was very interested in the questions that were coming out of the neutrino experiments, and also I didn’t really want to join an enormously large collaboration. I was more interested in the funny little anomalies that were already showing up in the neutrino world than I was in a particle which had to exist — the top quark — and the question of what was its precise mass. I am really, I suppose, an anomaly chaser. I admit it. Some people might call it an epithet. I wear it with pride.
One of those anomalies was the hint of an extra type of neutrino beyond the three known flavors in the Standard Model. That result from LSND was such an outlier that some physicists suggested dismissing it. Instead, you helped lead an experiment at Fermilab, called MiniBooNE, to follow up on it. Why?
You’re not allowed to throw out data, I’m sorry. That is exactly how to miss important new physics. We can’t be so in love with our Standard Model that we aren’t willing to question it. Even if the question doesn’t align with our prejudices, we have to ask the question anyway. When I started out, nobody was really interested in sterile neutrinos. It was a lonely land out there.
MiniBooNE’s results have added to the mystery. In one set of experiments using antineutrinos, it found LSND-like hints of sterile neutrinos, and in another, using neutrinos, it did not.
The antineutrino result matched up with LSND very well, but the neutrino result, which is the one we produced first, is the one that doesn’t match up. The whole world would be a very different place if we had started with antineutrino running and gotten a result that matched LSND. I think there would have been a lot more interest immediately in the sterile-neutrino question. We would have been where we are now at least 10 years earlier.
Where are we now?
There are eight experiments total that have anomalies suggesting the presence of more than the three known flavors of neutrino. There are also seven experiments that don’t. Recently, some of the experiments that have not seen an effect have gotten a lot of press, including IceCube, which is a result that my group worked on. A lot of press came out about how IceCube didn’t see a sterile-neutrino signal. But while the data rules out some of the possible sterile-neutrino masses, it doesn’t rule out all of them, a result we point out in an article that has just been published in Physical Review Letters.
Why are neutrino studies so hard?
Most neutrino experiments need very large detectors that need to be underground, almost always under mountains, to be protected from cosmic rays that themselves produce neutrinos. And all of the accelerator systems we build tend to be in plains — like Fermilab is in Illinois. So once you decide you’re going to build a beam and shoot it for such a long distance, the costs are enormous, and the beams are very difficult to design and produce.
Is there any way around these problems?
What I would really like to see is a future series of experiments that are really decisive. One possibility for this is IsoDAR, which is part of a larger experiment called DAEδALUS. IsoDAR will take a small cyclotron and use it as a driver to produce lithium-8 that decays, resulting in a very pure source of antielectron neutrinos. If we paired that with the KamLAND detector in Japan, then you would be able to see the whole neutrino oscillation. You don’t just measure an effect at a few points, you can trace the entire oscillation wave. The National Science Foundation has given us a little over $1 million to demonstrate the system can work. We’re excited about that.
Why would IsoDAR be a more decisive sterile-neutrino hunter?
This is a case where you don’t produce a beam in the normal way, by smashing protons into a target and using a series of magnetic fields to herd the resulting charged particles into a wide beam where they decay into several kinds of neutrinos, among other particles. Instead you allow the particle you produce, which has a short lifetime, to decay. And it decays uniformly into one kind of neutrino in all directions. All of the aspects of this neutrino beam — the flavor, the intensity, the energies — are driven by the interaction that’s involved in the decay, not by anything that human beings do. Human beings cannot screw up this beam! It’s really a new way of thinking and a new kind of source for the neutrino community that I think can become very widely used once we prove the first one.
So the resulting neutrino interactions are easier to interpret?
We’re talking about a signal-to-background ratio of 10 to one. By contrast, most of the reactor experiments looking for antineutrinos are running with a signal-to-background ratio of one to one if they do well, since the neutrons that come out of the reactor core can actually produce a signal that looks a lot like the antineutrino signal you are looking for.
Speaking of spectral signals, tell me about your connection with the recent Ghostbusters movie remake.
It’s the first movie I’ve consulted for. It happened because of Lindley Winslow. She was at the University of California, Los Angeles, before she came to MIT. At UCLA, she had made a certain amount of connection with the film industry, and so they had gotten in touch with her. She showed them my office, and they really liked my books. My books are stars — you do get to see them in the movie and some of the other things from my office here and there. When they brought the books back, they put them all back exactly the way they were. What’s really funny about that was that they were not in any order.
What did you think of the movie itself? Did you relate to the way Kristen Wiig played a physicist?
I was really happy to see a whole new rendering of it. To watch the characters interact; I think there was a lot of impromptu work. It really came through that these women resonated with each other. In the movie, Kristen Wiig goes into an empty auditorium and she rehearses for her lecture. I felt for that character. When I started out as a faculty member, I had very little experience as somebody who actually taught — I had done all this research. It’s kind of ridiculous to think about now, but I went through those first lectures and really rehearsed them.
In a way, your career has come full circle, since you started out working at a cyclotron in college and now you want to use another one to hunt for sterile neutrinos. Can you really do cutting-edge research with cyclotrons that accelerate particles to energies just a thousandth of a percent of those reached at the Large Hadron Collider?
Cyclotrons were invented back at the beginning of the last century. They were limited in energy, and as a result, they went out of fashion as particle physicists decided that they needed larger and larger accelerators going up to higher and higher energies. But in the meantime, the research that was done for the nuclear physics community and also for medical isotopes and for treating people with cancer took cyclotrons in a whole different direction. They’ve turned into these amazing machines, which now we can bring back to particle physics. There are questions that can perhaps be better answered if you are working at lower energies but with much purer beams, with more intense beams, and with much better-understood beams. And they’re really nice because they’re small. You can bring your cyclotron to your ultra-large detector, whereas it’s very hard to move Fermilab to your ultra-large detector.
A single type of sterile neutrino is hard to reconcile with existing experiments, right?
I think the little beast looks different from what we thought. The very simplistic model introduces only one sterile neutrino. That would be a little weird if you were guided by patterns. If you look at the patterns of all the other particles, they’re appearing in sets of three. If you introduce three, and you do all the dynamics between them properly, does that fix the problem? People have taken a few steps toward answering that, but we’re still doing approximations.
You just called the sterile neutrino a “little beast.” Do you anthropomorphize particles?
There’s no question about that. They all have these great little personalities. The quarks are the mean girls. They’re stuck in their little cliques and they won’t come out. The electron is the girl next door. She’s the one you can always depend on to be your friend — you plug in and there she is, right? And she’s much more interesting than people would think. What I like about the neutrinos is they’re very independent. With that said, with neutrinos as friends, you will never be lonely, because there are a billion neutrinos in every cubic meter of space. I have opinions about all of them.
When did you start creating these characterizations?
I’ve always thought about them that way. I have in fact been criticized for thinking about them that way and I don’t care. I don’t know how you think about things that are disconnected from your own experience. You have to be really careful not to go down a route that you shouldn’t go down, but it’s a way of thinking about things that’s completely legitimate and gives you some context. I still remember once describing some of the work I was doing as fun. I had one physicist say to me, “This is not fun; this is serious research.” I was, like, you know, serious research can be a lot of fun. Being fun doesn’t make it less important — those are not mutually exclusive.
This article was reprinted on Wired.com. | 0.861038 | 3.943934 |
Another extrasolar planet has been found, this time a Neptune-sized world orbiting a star 120 light-years from Earth. It was found by a network of automated telescopes set up to search for other worlds, known as “HATNet,” which is operated by the Center in Arizona and Hawaii. This latest extrasolar world, called HAT-P-11b is the 11th planet found by HATNet, and the smallest yet discovered by any projects that are searching using the transit method. As a planet passes directly in front of (transits) its parent star, it blocks a small amount of light coming from the star. In this case, the planet blocked about 0.4 percent of the star’s light. This discovery puts the current extrasolar count at 335.
Transit detections are particularly useful because the amount of dimming tells the astronomers how big the planet must be. By combining transit data with measurements of the star’s “wobble” (radial velocity) made by large telescopes like Keck, astronomers can determine the mass of the planet.
While Neptune has a diameter 3.8 times that of Earth and a mass 17 times Earth’s, HAT-P-11b is 4.7 times the size of Earth and has 25 Earth masses.
A number of Neptune-like planets have been found recently by radial velocity searches, but HAT-P-11b is only the second Neptune-like planet found to transit its star, thus permitting the precise determination of its mass and radius.
The new-found world orbits very close to its star, revolving once every 4.88 days. As a result, it is baked to a temperature of around 1100 degrees F. The star itself is about three-fourths the size of our Sun and somewhat cooler.
There are signs of a second planet in the HAT-P-11 system, but more radial velocity data are needed to confirm that and determine its properties.
Another team has located one other transiting super-Neptune, known as GJ436b, around a different star. It was discovered by a radial velocity search and later found to have transits.
“Having two such objects to compare helps astronomers to test theories of planetary structure and formation,” said Harvard astronomer Gaspar Bakos, who led the discovery team.
HAT-P-11 is in the constellation Cygnus, which puts in it the field of view of NASA’s upcoming Kepler spacecraft. Kepler will search for extrasolar planets using the same transit technique pioneered by ground-based telescopes. This mission potentially could detect the first Earth-like world orbiting a distant star. “In addition, however, we expect Kepler to measure the detailed properties of HAT-P-11 with the extraordinary precision possible only from space,” said Robert Noyes, another member of the discovery team. | 0.821274 | 3.910926 |
At one time or another, most of us have probably used a Swiss Army Knife. An excellent everyday tool, it's really just a glorified pocket or penknife; a tool incorporating several blades and other appliances such as scissors and screwdrivers.
And ascending the northeast sky on February evenings is what we might call the "Swiss Army Knife of the sky": the Big Dipper. It is not an official constellation in itself; rather, it's a prominent grouping of stars (called an asterism) that forms a different type of star pattern within a recognized constellation — in this case, Ursa Major, the great bear.
But the Dipper is more than just a bright and familiar star pattern. It's a compass, a clock, a calendar and a ruler all rolled into one!
As a compass, we need only go to the two stars at the end of the bowl of the Dipper — Dubhe and Merak — known as the "pointer stars," which serve as a stellar compass needle, pointing directly toward Polaris, the North Star.
An imaginary line drawn and extended from Merak through Dubhe (at the top of the bowl) and extended about five times the distance between the two brings us unerringly to Polaris. Once you find Polaris, you're facing due north. Behind you is south; to your left is west and to your right is east.
We can also use the Dipper as a celestial clock. In his book "Star Lore of All Ages" (G.P. Putnam's Sons, 1911), William Tyler Olcott, the early 20th century American lawyer and amateur astronomer, wrote:
"The entire figure of the Great Bear circles about the pole once in twenty-four hours. This is, of course, an apparent motion due to the rotation of the Earth. A line connecting the 'pointer stars' with Polaris may be regarded as the hour hand of a clock. With a little practice, the time of night can be ascertained to an approximate degree by the position of this stellar hour hand."
The only thing that makes our sky clock different from the ones we have in our home (or around your wrist) is that the Big Dipper moves around Earth's geographic North Pole in a counterclockwise direction. What is required to learn how to tell the time using the Big Dipper, is a period of frequent comparison — repeated anew for each season — of the position of the line running from Polaris through the pointer stars with the local time on your clock.
The length of time required to do these observations depends on how assiduous an observer you are. Through a process of mental association between the celestial and mechanical hour hands, it becomes possible to estimate the time directly from the sky alone. With practice, this can be carried to a surprising degree of accuracy. I know some people who are able to tell what time it is using this methodology within just a few minutes of what the actual time happens to be! If you go out several nights a week, and note afterwards what the time is when you go back inside, after a while you won't need to check the clock or your watch — you'll pretty much know what hour of the night it is.
In addition to its role as a sort of cosmic chronometer, the Big Dipper can also serve as a calendar. From the relative position of the Big Dipper with respect to Polaris, the season of the year — and eventually with practice, even the month — can be determined by looking at the sky.
During the hours just after darkness falls in the spring, we can find the asterism soaring high above the northern horizon and stretching to the point almost directly overhead (the zenith). But by summer it has turned counterclockwise by 90 degrees; the bowl now points downward and it lies to the west of the pole during the early evening hours.
By fall evenings, the Big Dipper is far beneath Polaris and skims the northern horizon. This position in the sky is appropriate in a way, as bears are going into hibernation at this time of year, and as we mentioned earlier, the Big Dipper is part of the big bear constellation, which is now partially hidden below the northern horizon. And now, during the winter we find it ascending the sky once again, standing on its handle around 9 p.m. local time in the Northeast.
Finally, another valued and fascinating use of the Big Dipper is that we can use it as a convenient astronomical yardstick by which we can measure angular sizes and distances in the sky. Sky angles ranging from 5 to 25 degrees in extent can be determined using the stars of the Big Dipper. While other well-known asterisms, such as the Great Square of Pegasus in autumn, or constellations such as Orion in winter , can serve this same function, the Big Dipper is visible at all seasons and therefore is the most handy sky ruler of them all.
The gap between the pointer stars measures 5.5 degrees. Since the moon measures about one-half degree in apparent diameter on average, we could fit 11 full moons in the gap between Dubhe and Merak.
The next time you see the Big Dipper in the sky, study the distance between the two pointer stars and judge for yourself how many moons you might fit between them. It may look like only four or five can fit — but 11? This, along with the seemingly "bloated" appearance of a rising or setting moon, is one of the best optical illusions in the sky, but yes ... 11 full moons would indeed fit between the two pointer stars.
Getting back to our celestial measuring stick, the distance between the two stars across the bottom of the bowl (Merak and Phecda) is 7 degrees, while the two stars along the top (Dubhe and Megrez) are 10 degrees apart. From Dubhe to Alkaid (the star at the end of the handle) measures 25 degrees, and from Dubhe to Polaris stretches 28 degrees.
Some examples of the uses to which we might put this starry ruler include estimating the path length of a bright meteor or fireball streaking across the sky, or determining the length of the tail of a bright comet. As a further instance, suppose we read that a planet is to be visible on a certain evening 7 degrees north of the moon. A glance at the Big Dipper will provide the eye with an immediate "feel" for this distance.
For smaller night-sky measurements, check out the middle star in the handle of the Big Dipper. That's Mizar, and located just to its upper left is a smaller, dimmer star known as Alcor. If you have normal eyesight, you should be able to separate both stars without any optical aid. These two stars are separated by 12 arc minutes, or 0.2 degrees. That's less than half of the apparent diameter of the moon.
Keep that in the back of your mind, because later this year, on Dec. 21, Jupiter and Saturn are going to have an exceedingly close encounter with each other. In their closest approach since 1623, the planets will be separated by 6 arc minutes, or just one-half the distance of Mizar to Alcor. On that evening, you'll be able to fit both Jupiter and its four Galilean moons and Saturn and its famous rings in the same field of view of a high-power telescope.
Mark your calendars.
- The brightest planets in February's night sky: How to see them (and when)
- Big Dipper stars shine over stargazer in amazing photo
- A skywatcher shows you where to find the North Star (photo)
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers' Almanac and other publications. Follow us on Twitter @Spacedotcom and on Facebook. | 0.908772 | 3.796674 |
The Virgo Cluster of Galaxies
is the closest cluster of galaxies to our Milky Way Galaxy
. The Virgo Cluster
is so close that it spans more than 5 degrees
on the sky - about 10 times the angle made by a full Moon
. With its heart lying about 70 million light years distant, the Virgo Cluster
is the nearest cluster of galaxies
, contains over 2,000 galaxies, and has a noticeable gravitational pull on the galaxies of the Local Group of Galaxies
surrounding our Milky Way Galaxy
. The cluster
contains not only galaxies filled with stars but also gas
so hot it glows in X-rays
. Motions of galaxies
in and around clusters indicate that they contain more dark matter
than any visible matter we can see. Pictured above
, the heart of the Virgo Cluster
includes bright Messier
galaxies such as Markarian's Eyes
on the upper left, M86
just to the upper right of center, M84
on the far right, as well as spiral galaxy NGC 4388
at the bottom right.
Has a solar eclipse ever been seen from the Moon? Yes, first in 1967 -- but it may happen again next week. The robotic Surveyor 3 mission took thousands of wide angle television images of the Earth in 1967, a few of which captured the Earth moving in front of the Sun. Several of these images have been retrieved from the NASA archives and compiled into the above time-lapse video. Although the images are grainy, the Earth's atmosphere clearly refracted sunlight around it and showed a beading effect when some paths were blocked by clouds. Two years later, in 1969, the Apollo 12 crew saw firsthand a different eclipse of the Sun by the Earth on the way back from the Moon. In 2009, Japan's robotic Kaguya spacecraft took higher resolution images of a similar eclipse while orbiting the Moon. Next week, however, China's Chang'e 3 mission, including its Yutu rover, might witness a new total eclipse of the Sun by the Earth from surface of the Moon. Simultaneously, from lunar orbit, NASA's LADEE mission might also capture the unusual April 15 event. Another angle of this same event will surely be visible to people on Earth -- a total lunar eclipse.
Just days after sharing the western evening sky with Venus in 2007, the Moon moved on to Saturn - actually passing in front of the ringed planet Saturn when viewed in skies over Europe, northern Africa, and western Asia. Because the Moon and bright planets wander through the sky near the ecliptic plane, such occultation events are not uncommon, but they are dramatic, especially in telescopic views. For example, in this sharp image Saturn is captured emerging from behind the Moon, giving the illusion that it lies just beyond the Moon's bright edge. Of course, the Moon is a mere 400 thousand kilometers away, compared to Saturn's distance of 1.4 billion kilometers. Taken with a digital camera and 20 inch diameter telescope at the Weikersheim Observatory in southern Germany, the picture is a single exposure adjusted to reduce the difference in brightness between Saturn and the cratered lunar surface.
Sister planet stands
together with sister stars.
Celebrate the sky.
NGC 2438 is a planetary nebula, the gaseous shroud cast off by a dying sunlike star billions of years old whose central reservoir of hydrogen fuel has been exhausted. About 3,000 light-years distant it lies within the boundaries of the nautical constellation Puppis. Remarkably, NGC 2438 also seems to lie on the outskirts of bright, relatively young open star cluster M46. But this planetary nebula's central star is not only much older than the stars of M46, it moves through space at a different speed than the cluster stars. Distance estimates also place NGC 2438 closer than M46 and so the nebula appears in the foreground, only by chance along the line-of-sight to the young star cluster. This deep image of NGC 2438 highlights a halo of glowing atomic gas over 4.5 light-years across, extending beyond the nebula's brighter inner ring. Similar haloes have been found in deep images of other planetary nebulae, produced during the earlier active phases of their aging central stars.
In this twilight skyview, a windmill stands in silent witness to a lovely pairing of planets in the west. The picture was recorded on April 5 from Gallegos del Campo, Zamora, Spain. Venus (left) and Mercury (right) are near their much anticipated conjunction in the early evening sky. But even in the coming days, these two evening stars will remain close in the western sky at sunset. In fact, with brighter Venus as a marker, sky watchers will have an excellent guide for spotting Mercury nearby, a planet often hidden in the Sun's glare.
Two galaxies are squaring off in Virgo and here are the latest pictures. When two galaxies collide, the stars that compose them usually do not. This is because galaxies are mostly empty space and, however bright, stars only take up only a small fraction of that space. But during the collision, one galaxy can rip the other apart gravitationally, and dust and gas common to both galaxies does collide. If the two galaxies merge, black holes that likely resided in each galaxy center may eventually merge. Because the distances are so large, the whole thing takes place in slow motion -- over hundreds of millions of years. Besides the two large spiral galaxies, a smaller third galaxy is visible on the far left of the above image of Arp 274, also known as NGC 5679. Arp 274 spans about 200,000 light years across and lies about 400 million light years away toward the constellation of Virgo.
What caused this unusual white rock formation on Mars? Intrigued by the possibility that they could be salt deposits left over as an ancient lakebed dried-up, detailed studies of these fingers now indicate that this is not correct. The light material appears to have eroded away from the surrounding area, indicating a very low-density composition, possibly consistent with volcanic ash or windblown dust. The stark contrast between the rocks and the surrounding sand is compounded by the sand's unusual darkness. This picture was taken from the Mars Express spacecraft currently orbiting Mars. Planetary scientist Emily Lakdawalla, among others, has followed her curiosity about this unusual Martian landform into a fascinating investigation that is eloquently described in the Planetary Society Weblog. The mysterious white rock spans about 15 kilometers across inside a larger crater that spans about 100 kilometers.
Using an image recorded just last month as a base, this composite illustration tracks the motion of bright Saturn as it wanders through planet Earth's night sky. Starting at the upper right, Saturn's position is shown about every two weeks beginning in August 2005 and projected through September 2008. Over the three year period, Saturn actually appears to reverse its general eastward (leftward) drift, tracing out three flattened curves. The periodic backwards or retrograde motion with respect to the background stars is a reflection of the motion of the Earth itself. Retrograde motion can be seen each time Earth overtakes and laps planets orbiting farther from the Sun, the Earth moving more rapidly through its own closer-in orbit. The Beehive star cluster in Cancer lies near the track at the upper right. Stars along the "backward question mark" at the head of Leo are in the left half of the frame. Saturn's position this month is near the right hand limit of the middle curve. Click on the picture to download and view the gif animation
During a total solar eclipse, the Sun's extensive outer atmosphere or corona is an awesome and inspirational sight. The subtle shades and shimmering features of the corona that engage the eye span a brightness range of over 10,000 to 1, making them notoriously difficult to capture in a single picture. But this composite of 33 digital images ranging in exposure time from 1/8000 to 1/5 second comes very close to revealing the crown of the Sun in all its glory. The telescopic views were recorded from Side, Turkey during the March 29 solar eclipse, a geocentric celestial event that was widely seen under nearly ideal conditions. The composite also captures a pinkish prominence extending just beyond the upper edge of the eclipsed sun.
Friday's solar eclipse will be a rare hybrid - briefly appearing as either an annular eclipse or a total eclipse when viewed from along the narrow track of the Moon's shadow. Unfortunately that track, never more than about 30 kilometers wide, lies mostly across the Pacific Ocean, beginning south of New Zealand and just ending in Venezuela. Skywatchers along the beginning and end of the shadow track will see an annular eclipse of the Sun, with the Moon's silhouette briefly surrounded by a bright ring of fire, while observers along the middle of the track will witness a total eclipse phase. But the good news is that over a much broader region of the globe, including New Zealand and much of South and North America, a partial eclipse can be seen as the Moon appears to take a bite out of the Sun. If you want to view the eclipse, take care to do it safely, and check the times for your specific location. So, what location is this solar eclipse view from? The picture above was recorded in November of 2003 from within the track of the Moon's shadow across Antarctica, of course.
Why isn't spiral galaxy M66 symmetric? Usually density waves of gas, dust, and newly formed stars circle a spiral galaxy's center and create a nearly symmetric galaxy. The differences between M66's spiral arms and the apparent displacement of its nucleus are all likely caused by the tidal gravitational pull of nearby galaxy neighbor M65. Spiral galaxy M66, pictured above, spans about 100,000 light years, lies about 35 million light years distant, and is the largest galaxy in a group including M65 and NGC 3628 known as the Leo Triplet. Like many spiral galaxies, the long and intricate dust lanes of M66 are seen intertwined with the bright stars and nebulas that light up the spiral arms.
NGC 281 is a busy workshop of star formation. Prominent features include a small open cluster of stars, a diffuse red-glowing emission nebula, large lanes of obscuring gas and dust, and dense knots of dust and gas in which stars may still be forming. The open cluster of stars IC 1590 visible around the center has formed only in the last few million years. The brightest member of this cluster is actually a multiple-star system shining light that helps ionize the nebula's gas, causing the red glow visible throughout. The lanes of dust visible below the center are likely homes of future star formation. Particularly striking in the above photograph are the dark Bok globules visible against the bright nebula. Stars are surely forming there right now. The entire NGC 281 system lies about 10 thousand light years distant.
In 1787, astronomer William Herschel discovered the Eskimo Nebula. From the ground, NGC 2392 resembles a person's head surrounded by a parka hood. In 2000, the Hubble Space Telescope imaged the Eskimo Nebula. From space, the nebula displays gas clouds so complex they are not fully understood. The Eskimo Nebula is clearly a planetary nebula, and the gas seen above composed the outer layers of a Sun-like star only 10,000 years ago. The inner filaments visible above are being ejected by strong wind of particles from the central star. The outer disk contains unusual light-year long orange filaments. The Eskimo Nebula lies about 5000 light-years away and is visible with a small telescope in the constellation of Gemini.
This week's stereo offering features the now famous Active Region 9393, the largest sunspot group in the last 10 years. Viewed with red/blue glasses, the stereo pair of images merges into one 3D representation of the Sun with AR9393 above and right of center. The images were recorded in extreme ultraviolet light and AR9393 is seen as an extensive array of bright patches laced with large graceful loops of arcing plasma. In the extreme ultraviolet, active regions outshine the solar surface, just the reverse of their appearance as dark sunspots against a bright photosphere when viewed in visible light. Recorded 96 minutes apart on March 30 by the space-based SOHO EIT camera, the pair produces an exaggerated but pleasing stereo effect due to solar rotation -- the Sun's surface moving slightly between the two exposures to offer different perspectives.
Planetary nebulae do look simple, round, and planet-like in small telescopes. But images from the orbiting Hubble Space Telescope have become well known for showing these fluorescent gas shrouds of dying Sun-like stars to possess a staggering variety of detailed symmetries and shapes. This composite color Hubble image of NGC 6751 is a beautiful example of a classic planetary nebula with complex features and was selected to commemorate the tenth anniversary of Hubble in orbit. The colors were chosen to represent the relative temperature of the gas - blue, orange, and red indicating the hottest to coolest gas. Winds and radiation from the intensely hot central star (140,000 degrees Celsius) have apparently created the nebula's streamer-like features. The nebula's actual diameter is approximately 0.8 light-years or about 600 times the size of our solar system. NGC 6751 is 6,500 light-years distant in the constellation Aquila.
The star cluster at lower right, cataloged as Hodge 301, is a denizen of the Tarantula Nebula. An evocative nebula in the southern sky, the sprawling cosmic Tarantula is an energetic star forming region some 168,000 light-years distant in our neighboring galaxy the Large Magellanic Cloud. The stars within Hodge 301 formed together tens of millions of years ago and as the massive ones quickly exhaust their nuclear fuel they explode. In fact, the red giant stars of Hodge 301 are rapidly approaching this violent final phase of stellar evolution - known as a supernova. These supernova blasts send material and shock waves back into the nebular gas to create the Tarantula's glowing filaments also visible in this Hubble Space Telescope Heritage image. But these spectacular stellar death explosions signal star birth as well, as the blast waves condense gas and dust to ultimately form the next generation of stars inside the Tarantula Nebula.
Yesterday the Mars Global Surveyor project released a new close-up image of a portion of the Cydonia region on Mars. This cropped and processed version shows an area about 2 miles wide (the full version covers a strip nearly 2.6 miles wide by 25 miles long) and at full resolution has a pixel size of about 14 feet. The rock formation visible is the famous feature seen as the "Face on Mars" in 1976 Viking orbiter images. Such complex looking landforms in the Cydonia region are thought to be the result of erosion and weathering of ancient crust by Martian winds, frost, and possibly surface water. Mars Global Surveyor is scheduled to take other images of the Cydonia region and the Mars Pathfinder and Viking landing sites this month.
Could this fuzzy blob be the key to the whole gamma-ray burst (GRB) mystery? Astronomers the world over are now scrambling to determine the true nature of the extended emission seen to the lower right of the bright source in the above image. The bright object in the center is rapidly fading - and thought to be the first true optical counterpart to a GRB. But is it housed in a galaxy? If so, after the central emission has faded, this galaxy should be identifiable. Today, follow up observations of this blob are planned with the Hubble Space Telescope. If the extended emission does come from a galaxy it would bolster indications that the February 28th GRB occurred in that galaxy, across the universe from us. This, in turn, would imply that GRBs are truly the most powerful explosions ever known.
Why is Umbriel so dark? This dark moon reflects only half the light of other Uranus' moons such as Ariel. And what is that bright ring at the top? Unfortunately, nobody yet knows. These questions presented themselves when Voyager 2 passed this satellite of Uranus in January 1986. Voyager found an old surface with unusually large craters, and determined Umbriel's composition to be about half ice and half rock. Umbriel is the fourth largest and third most distant of Uranus' five large moons. Umbriel was discovered in 1851 by William Lassell. | 0.924727 | 3.720537 |
Massive Mysterious Rogue Planet Observed Moving Just Outside our Solar System
Maybe this Planet X or Nibiru? It is only 20 light years away (fairly close in terms of celestial distances).
A mysterious large object is floating around outside our solar system and researchers aren’t sure exactly what it is – although it could be a rogue planet.
In the first radio-telescope detection of a planetary-mass object beyond our solar system, astronomers have found the strange celestial body has 12.7 times the mass of Jupiter. It doesn’t appear to orbit a parent star, however, and is only 20 light-years away from Earth.
“This object is right at the boundary between a planet and a brown dwarf, or ‘failed star,’ and is giving us some surprises that can potentially help us understand magnetic processes on both stars and planets,” study lead astronomer Melodie Kao said.
A brown dwarf is an object too large to be a planet, but isn’t big enough to sustain the nuclear fusion of hydrogen in its core that is vital to stars.
The object, which has been named SIMP J01365663+0933473, was first detected in 2016, but was thought to be a brown dwarf. The latest data reveals it’s younger than first thought at a relatively youthful 200 million years old, and its mass is smaller, so it could be classified as a planet. Its temperature is also far cooler than the sun, at 825 degrees Celsius. It also has a strong magnetic field, 200 times the strength of Jupiter.
The researchers were able to pick up on the object’s magnetic activity using a powerful radio astronomy observatory called the Very Large Array, a National Science Foundation facility in New Mexico.
The methods used suggest the researchers may have “a new way of detecting exoplanets, including the elusive rogue ones not orbiting a parent star,” researcher Gregg Hallinan said. | 0.893857 | 3.454345 |
In this first episode of Catastrophe series, host Tony Robinson speaks with planetary experts, archaeologists and paleontologists to understand one of our solar system's first great disasters and its most notable outcome: the emergence of our Moon and oceans and their roles in enabling life on Earth.
In the early stages of our solar system's development, Earth had a twin planet that shared its orbit around the sun. According to Planetary Scientist William K. Hartman when this planet, Thea, ultimately collided with Earth it destroyed itself and created a ring of debris around its sister planet. This ring of debris eventually settled, leaving behind the lunar body we now know as our Moon. Astrophysicist Robin Canup speaks in support of this theory, providing evidence in the form of computer models, which show how a planetary impact very likely created the Moon. It was also around this time the developing Earth's surface was struck by icy comets, in turn creating the world's first oceans.
Paleontologist Judith Nagel-Myers presents fossilized corals found in Ithaca, NY, which indicate the moon was once ten times closer to the Earth's surface. The strength of its gravitational pull resulted in massive tides that spread water across the planet, pulling in a combination of minerals and nutrients that created a "primordial soup" and gave way to the proteins and amino acids necessary for the emergence of life. An Earth-Moon "waltz" was set into motion, with the Moon continuing to influence tides as it slowly spins away from Earth even to this day. As cyanobacteria began to develop in the Earth's waters photosynthesis developed, introducing oxygen to the oceans and atmosphere and eventually giving way to the evolution of complex life forms.
As one subject notes, "A catastrophe is always, in some respect, a beginning." The sheer scope of chance that was at play in our creation is presented here with a sense of awe and great respect. Catastrophe: Birth of the Planet is just the tip of the proverbial iceberg in this documentary series concerning the arbitrary and brutal events that paved the way for modern life. | 0.897517 | 3.021733 |
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FOR IMMEDIATE RELEASEJune 29, 1998
WATER HISTORY, ROCK COMPOSITION AMONG LATEST FINDINGS A YEAR AFTER MARS PATHFINDER
A year after the landing of Mars Pathfinder, mission scientists say that data from the spacecraft paint two strikingly different pictures of the role of water on the red planet, and yield surprising conclusions about the composition of rocks at the landing site.
"Many of the things that we said last summer during the excitement after the landing have held up well," said Dr. Matthew Golombek, Pathfinder project scientist at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA. "But we have now had more time to study the data and are coming up with some new conclusions."
Similar to on-going science results from NASA's Mars Global Surveyor spacecraft currently in orbit around Mars, Pathfinder data suggest that the planet may have been awash in water three billion to 4.5 billion years ago. The immediate vicinity of the Pathfinder landing site, however, appears to have been dry and unchanged for the past two billion years.
Several clues from Pathfinder data point to a wet and warm early history on Mars, according to Golombek. Magnetized dust particles and the possible presence of rocks that are conglomerates of smaller rocks, pebbles and soil suggest copious water in the distant past. In addition, the bulk of the landing site appears to have been deposited by large volumes of water, and the hills on the horizon known as Twin Peaks appear to be streamlined islands shaped by water.
But Pathfinder images also suggest that the landing site is essentially unchanged since catastrophic flooding sent rocks tumbling across the plain two billion years ago. "Since then this locale has been dry and static," he said.
While the area appears to have been untouched by water for eons, wind appears to have been steadily eroding rocks at the landing site. Analysis of Pathfinder images shows that about about three to five centimeters (one to two inches) of material has been stripped away from the surface by wind, Golombek noted.
"Overall, this site has experienced a net erosion in recent times," said Golombek. "There are other places on Mars that are net 'sinks,' or places where dust ends up being deposited. Amazonis Planitia, for example, probably has about one to two meters (three to six feet) of fine, powdery dust that you would sink into if you stepped on it."
Chemical analysis of a number of rocks by the alpha proton X-ray spectrometer (APXS) instrument on Pathfinder's mobile Sojourner rover, meanwhile, reveals an unexpected composition that scientists are still trying to explain.
The current assessment of data from this instrument suggests that all of the rocks studied by the rover resemble a type of volcanic rock with a high silicon content known on Earth as andesite, covered with a fine layer of dust. All of the rocks appear to be chemically far different from meteorites discovered on Earth that are believed to have come from Mars.
"The APXS tells us that all of these rocks are the same thing with different amounts of dust on them," said Golombek. "But images suggest that there are different types of rocks. We don't yet know how to reconcile this."
When molten magma oozes up from a planet's mantle onto the surface of the outer crust, it usually freezes into igneous rock of a type that geologists call a basalt. This is typical on the floors of Earth's oceans, as well as on the maria of the Moon and in many regions of Mercury and Venus. By contrast, andesites typically form on Earth in tectonically active regions when magma rises into pockets within the crust, where some of its iron and magnesium-rich components are removed, leaving rock with a higher silicon content. "We don't believe that Mars has had plate tectonics, so these andesites must have formed by a different mechanism," Golombek said.
The rocks studied by Pathfinder most closely resemble andesites found in Iceland and the Galapagos Islands, tectonic spreading centers where plates are being pushed apart, said Dr. Joy Crisp, an investigation scientist on the spectrometer experiment at JPL. Andesites from these areas have a different chemical signature from andesites formed at subduction zones, mostly because wet ocean sediments carry more water down into the mantle at the subduction zones. "On Mars, where the water content is probably lower and there is no evidence of subduction, we would expect a closer chemical similarity to Iceland andesites," said Crisp.
The Martian rocks may have other origins, however. They could be sedimentary and influenced by water processes; they could be formed by melting processes resulting from a meteor impact; or, a third alternative is that the rocks might be basaltic, but covered by a silicon-rich weathering coating. "In any event, the presence of andesites on Mars is a surprise, if it is borne out as we study the data further," said Crisp. "Most rocks on Mars are expected to be basalts lower in silicon. If these are in fact andesites, they are probably not very abundant."
Pathfinder scientists are looking forward to more data from the Thermal Emission Spectrometer instrument on the Mars Global Surveyor to reveal more about the chemical composition of the planet's surface, especially once the orbiting spacecraft begins its prime circular mapping mission in spring 1999.
In other recent Pathfinder science findings, Dr. Steven Metzger of the University of Nevada found direct evidence of gusting winds called "dust devils" in images from Pathfinder's lander. Such dust devils had been seen in some Viking orbiter images and inferred from measurements of atmospheric pressure and winds by other instruments on the Pathfinder lander, but were not spotted in actual surface images until Metzger's discovery.
JPL planetary scientist Dr. Diana Blaney has been using data from Pathfinder, other spacecraft missions and ground-based observations to study weathering on Mars. Her work suggests that Mars is uniformly covered by a fine coating of dust formed by an unusual process involving meteor impacts and volcanic gases that add sulfur.
NASA's next Mars missions, the 1998 Mars Climate Orbiter and Mars Polar Lander, are in testing now for launch in December and January, respectively. Whereas Pathfinder's science focus was on exploring rocks with its mobile robotic geologist, the Mars Polar Lander will focus on a search for water under the planet's surface, equipped with a robot arm that will dig into the soil at the landing site near the planet's south pole.
Launched on December 4, 1996, Pathfinder reached Mars on July 4, 1997, directly entering the planet's atmosphere and bouncing on inflated airbags as a technology demonstration of a new way to deliver a lander and rover to Mars. The lander operated nearly three times its design lifetime of 30 days, while the rover operated 12 times its design lifetime of seven days.
During the mission, the spacecraft relayed an unprecedented 2.3 gigabits of data, including 16,500 images from the lander's camera, 550 images from the rover camera, 16 chemical analyses of rocks and soil, and 8.5 million measurements of atmospheric pressure, temperature and wind.
Mars Pathfinder was designed, built and operated by JPL for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA. | 0.84324 | 3.540092 |
This quite amazing view was captured with the help of NASA and ESA Hubble Space Telescope, and it is actually helping scientists a lot in understanding the universe. The galaxy, which appears multiple times in the image, has been nicknamed the Sunburst Arc, and it is placed almost 11 billion light-years away from us.
This Sunburst Arc galaxy is really just one simple, the regular universe, however, duplicated of it made their appearance multiple times in the image caught by scientists, because of an effect that’s called strong gravitational lensing. When talking about a gravitational lens, we refer to matter, that had the direction of light passing nearby it, which was distorted because of the gravity bending the space in the gravitational field. We know it sounds confusing, but it’s actually an illusion of light, which can make a single object appear multiple times.
The Sunburst Arc was lensed multiple times in this image with the light and mass from the giant cluster of galaxies that we can see behind. The galaxy cluster is so large that it can bend, and it can magnify the light from the distant Sunburst Arc galaxy.
This gravitational leasing has resulted in 4 bright light arcs, which are seen in the image. One arc is seen in the lower left, and the other three are seen in the top right. The galaxy appears multiple times in every arc. Hubble used a cosmic magnifying lens in order to study such an object. It actually allowed scientists to study farther away areas of the universe and to get amazing details.
The researchers that observed the Sunburst Arc think it was made in an era which started 150 million years after the Big Bang.
Kim Caldwell helped bring HenriLeChatNoir from a weekly newsletter to a full-fledged news site by creating a new website and branding. She continues to assist in keeping the site responsive and well organized for the readers. As a contributor to HenriLeChatNoir, Kim mainly covers mobile news and gadgets. | 0.857702 | 3.114426 |
Fast radio burst with steady 16-day cycle observed
by Bob Yirka , Phys.org
February 14, 2020
Credit: CC0 Public Domain
A large team of space scientists working in Canada has found evidence of a fast radio burst with a steady 16-day cycle. The team has published a paper describing their findings on the arXiv preprint server.
Fast radio bursts (FRBs) are, as their name suggests, short bursts of radio emissions that are detected by space scientists listening for signals from outer space. They appear randomly for a very short period of time, making them difficult to find and very hard to study. One was first observed back in 2007—since that time, several others have been observed—but only 10 of them have been found to repeat themselves. In this new effort, the researchers have observed the first instance of a repeating FRB, which repeats in a steady cycle.
Despite a lot of effort, space scientists do not know the source of FRBs, and have been developing theories—some suggest they might be nothing more than the noise created when two stars collide. Some non-professionals have suggested they are messages from aliens.
In this new effort, the researchers were studying data from the radio telescope used by the Canadian Hydrogen Intensity Mapping Experiment. When they spotted the FRB, they traced back 400 observations made using the telescope and determined that the FRB repeated in a steady, 16-day pattern. The FRB signals were observed to arrive approximately once an hour for four days and then suddenly cease—only to start up again 12 days later.
The repeating pattern suggests the source could be a celestial body of some kind orbiting around a star or another body. In such a scenario, the signals would cease when they are obstructed by the other body. But that still does not explain how a celestial body could be sending out such signals on a regular basis. Another possibility is that stellar winds might be alternately boosting or blocking signals from a body behind them. Or it could be that the source is a celestial body that is rotating.
The researchers traced the source of the FRB to a spiral galaxy approximately 500 million light-years away. They suggest future technology might be able to pinpoint which of the objects in the galaxy is sending out the FRBs and perhaps reveal how it is doing so. | 0.860767 | 3.660197 |
There are several pieces of research on the relations between the inferior conjunctions of Venus and the influenza pandemics that emerged in the 20th century. One research I read years ago has clearly stated that inferior conjunctions of Venus were directly related to pandemics. The inferior conjunction of Venus with the Sun occurs in every 583.9 days, which is approximately every 1.5 years. Of course, we do not experience a pandemic in each inferior conjunction of Venus! However, solar winds, which are active during such conjunctions are determinants on this theme.
Venus-Sun inferior conjunction and solar winds
I have emphasized this relation between the inferior conjunctions of Venus and solar activities in my book Maximum, which has been published in 2012. Under the title Venus Ingress in 2012 and Our Health, I underlined: “Some scientists claim that the virus that causes endemic flu emanates from Venus. Donald Barber from Norman Lockyer Observatory in Britain stated that some fungi-type bacteria that emanated from rainwater were linked with the Venus–Sun inferior conjunction. Barber also stated that six major epidemic diseases emerged 55 days after the geomagnetic storms that followed the Venus–Sun inferior conjunction. To summarize these scientific theories: Because some planetary alignments cause solar activities, Venus–Earth–Sun alignments also cause solar flares. As the magnetic field of Venus is too weak, ionized gases from its upper atmosphere leave the planet
due to solar storms. The bacterial colonies in these layers reach the Earth’s atmosphere during the planetary alignment. The viruses, which disseminate through the air from the poles, then cause flu epidemics around the world. We are now reaching the solar maximum phase, where we will experience increased magnetic currents. Because Venus’s plasma tail will be closer to the Earth during this interaction, the possibilities for virus contagion will increase. Throughout history, flu virus mutations and other pandemics were linked with sun spot maximums. For example, following the sun spot maximum in 1917, the Spanish Flu pandemic started in 1918”.
Magneto tail of Venus
When compared with the Earth, Venus has a much weaker magnetic field. It means, solar winds may deteriorate its atmosphere directly and blow its tail like upper atmosphere. Although it is not seen with naked eye, Venus has a tail similar to a comet. In his article The Interaction of the Solar Wind with Venus, Russell Vaisberg tells us, “While the Venus ionosphere, rather than magnetosphere as on the earth, deflects the solar wind flow, this deflection is accomplished with the deformation of a bow shock which heats and compresses the solar wind flow, and is closer to the planet and weaker than would be expected for an ideal gas dynamic interaction with a perfectly reflecting obstacle. The ionized magneto sheath flow can interact directly with the neutral atmosphere through charge exchange, which removes momentum from the flow, and photoionization; both processes adding mass to the solar wind because the high altitude neutral atmosphere is mostly composed of oxygen rather than hydrogen. The magneto tail of Venus also differs from that of the earth in that the mass loading of the magneto sheath flow slows the transport of magnetic flux tubes past the planet, while the ends of the tubes continue to travel rapidly in the solar wind, so that the planet accretes interplanetary magnetic flux.
Do Viruses come from Space?
According to scientists Hoyle and Wickramasinghe, flu outbreaks are often caused by new viruses from space. Based on a theory, the worst influenza outbreaks peak in correlation with sunspot activities of eleven years. Although particles are scattered all around the world, they are spread by people in places with high population, and therefore, the probability of transmission increases. The shortest interval between the geomagnetic storms and pandemics is 35 days, while the longest interval is 67 days.
Scientist Donald R.Barber claimed that bacteria reach the polar regions of the world by solar winds from the upper atmosphere of Venus. Another scientist, Joseph Norman Lockyer, stated they that bacteria reaches the ground from the sky in England through the north-west winds coming from North Polar Region. Therefore, virus spreads quickly because of being transmitted by the winds from the people. In the region where outbreaks occur, if there is no reason for the virus impact, then it is possible that influenza may occur due to the influence of Venus.-
In an article written by Lauren Compton on May 23, 2003, it is told that in a letter to The Lancet medical journal, Professor Chandra Wickramasinghe of Cardiff University suggests the SARS virus might be introduced to Earth by a comet or meteorite. He points to other mysterious modern epidemics like the Plague of Athens and the influenza pandemic of 1917-19 as also originating from the skies.
In the article titled “On the Possibility of microbiota transfer from Venus to Earth” written by N.C.Wickramasinghe and J.T. Wickramasinghe, it is stated that the action of the solar wind leads to erosion of parts of the atmosphere laden with aerosols and putative microorganisms, forming a comet-like tail in the anti-solar direction. As stated by the research, during inferior conjunctions that coincide with transits of the planet Venus, this comet-like tail intersects the Earth’s magnetopause and injects aerosol particles.
Inferior conjunctions of Venus and pandemics
Let’s have a look at the biggest outbreaks, which occurred around the dates of Venus-Sun inferior conjunction.
Venus-Sun inferior conjunction occurred on February 9, 1918 and Spanish Flu emerged on March 11, 1918.
Venus-Sun inferior conjunction occurred on June 21, 1956. Asian Flu, which emerged in Moscow in October 1956, spread to countries worldwide after February 1957.
Venus-Sun inferior conjunction occurred on June 13, 1988. Human Influenza A (H1N2) was seen in China between December 1988 and March 1989.
Venus-Sun inferior conjunction occurred on April 2, 1993. Hanta Virus emerged on May 1993.
Venus-Sun inferior conjunction occurred on August 18, 2007. A flu outbreak was seen in Australia on these days. Following the conjunction, Zika Virus emerged in April in the same year.
Venus-Sun inferior conjunction occurred on October 31, 2002. SARS outbreak emerged on November 16, 2002.
Venus-Sun inferior conjunction occurred on March 27, 2009. Swine Influenza A (H1N1) was seen in human in March 2009.
Venus-Sun inferior conjunction occurred on June 6, 2012. The first MERS case was seen on April 2012 (or on June some claims) and the outbreak spread to 26 countries by the end of 2012.
It is considered that COVID-19 emerged on December 1, 2019. The last Venus-Sun inferior conjunction occurred on October 26, 2018. It seems to be a long time between these days. And again, we will experience another Venus-Sun inferior conjunction on June 3, 2020 and before this conjunction, we will have a New Moon on May 22, 2020. I will give details about that coming conjunction at the end of my article. By the way, COVID-19 is a type of Coronavirus. In astronomy, corona means the outer sphere of the Sun, resembling a crown. Do you think it is a coincidence that Coronavirus has entered our lives during the transition period to the deep Solar Minimum cycle?
Sunspot Cycle Minima and Pandemics
According to some scientists, minima in the sunspot cycle present conditions conducive to the entry or activation of new pathogens and also for mutations of already circulating bacteria and viruses. Three grand minima of solar activity are on record – the Sporer minimum (1450-1550 AD), Maunder minimum (1650-1700 AD) and the Dalton minimum (1800-1830) have all been marked by a preponderance of pandemics – Small Pox, English Sweats, Plague and Cholera. The sunspot numbers recorded for the present period 2002-2017 include the deepest sunspot minimum (Cycle 23-24) since records began, and a trend to declining numbers throughout the cycle. The same period has seen the resurgence of several pandemics – SARS, MERS, Zika, Ebola, Influenza A. We consider it prudent to take note of these facts whilst planning future strategies for pandemic surveillance and control.
The possibility of linking sunspots with pandemics was first suggested in 1977 by Hope-Simpson who pointed out that many pandemics of influenza in history occurred close to times of sunspot maxima. Maxima in the sunspot cycle are characterized by high daily sunspot numbers, frequent solar flares, coronal discharge,s and X-ray emission. Sunspot minima are characterized by a weakening of the interplanetary magnetic field near the Earth, which allows for the entry of Galactic Cosmic Rays as well as electrically charged bacteria and viruses to the Earth and other microscopic biological entities can penetrate the interplanetary magnetic field barrier and reach the stratosphere. It is also of interest to note that the first descent of viral-sized particles deposited in the stratosphere will occur at places where the stratosphere is thinnest; and by this argument populated areas of China lying eastward of the Himalayan mountain range would present the best candidates. It is therefore not surprising to find that first strikes of new or renewed viral diseases are often recorded in China.
According to some scientists, from past records of the correlation of the sunspot cycle (prolonged minima) and pandemics it is clear that the onset of a deep minimum is a signal of action. We have stated elsewhere that the sunspot cycle could be a guide for closer scrutiny of circulating viruses, and monitoring their genetic variations.
In my book Maximum, published in 2012, I have stated that the decrease in solar activities had some negative influences on human health and connections with fatal outbreaks: “According to Solco W. Tromp, if we are not stimulated by the Sun we may experience health problems. Our life is restricted during low solar activities. Colonel C.A. Gill and Dr. Conyers Morrel state that the deadly pandemic diseases increase during minimal sun spot activity periods. Gill proved that all malaria cases occurred during low sun spot activities. According to Dr. Conyers Morrel, epidemic diseases were highly related with sun spot cycles. Diphtheria, tetanus and dysentery are triggered when there are no sun spots.”
As I stated in the book “Başlangıç 2020” a co-authored book in Turkish, “Based on some prediction techniques, scientists state that the existing Solar Minimum will reach its deepest point in April 2020 (+/- 6 months) and will reach a new Solar Maximum in July 2025”. It means, within the period between April 2020 and October 2020, we will experience the deepest point of the existing Solar Minimum. It is also stated that its trough will be experienced in 2022.
Coronavirus could turn to global pandemic as freak solar minimum means outbreak ‘imminent’
Lead author Chandra Wickramasinghe of the Buckingham Centre for Astrobiology has already stated that a global virus pandemic was imminent. In his article published in January 25, 2020, he says; “The “deepest sunspot minimum” for more than a century is about to force the Sun into partial hibernation, they say. Public health authorities have been warned to be vigilant with the phenomenon linked to historic viral pandemics. Previously unseen strains could emerge through the coming months while existing ones turn super-virulent, according to a report in Current Science. On the basis of sunspot numbers, this could have serious consequences globally during the coming months. The solar slump is causing the Earth’s magnetic field to weaken allowing “biological entities” including DNA to fall to the planet’s surface. Scientists believe infective agents originating from comets and other planets inhabit near space in a type of soup – the so-called panspermia theory. While they can naturally drift towards Earth, they are largely held at bay by magnetic fields, which are strengthened by solar activity. The imminent reduction in solar activity will knock a chink in this armour while “opening the floodgates” to a “flux of cosmic rays”. These rays threaten to disrupt the DNA present in bacteria and viruses already present, creating super-virulent versions. There are two problems we fear may arise: Biological entities can penetrate the weakened magnetic field under these circumstances to a much greater degree than under normal conditions. So we could see new, potentially deadly viruses, emerge on Earth after these floodgates are opened. Another aspect is mutations induced by cosmic rays in biological infectious agents already here, this could give them new characteristics and making then super-virulent. It would be prudent for public health authorities the world over to be vigilant and prepared for any necessary action. Previous viral pandemics have coincided with periods of low solar activity although scientists have struggled to find a definitive link. However they now think the effect of the sun on magnetic fields affects solar winds and the flow of charged particles including bacteria and viruses. Now, with space exploration and continuous monitoring of space weather, it is evident that the Earth’s magnetosphere and the interplanetary magnetic field in its vicinity are modulated by the solar wind that in turn controls the flow of charged particles onto the Earth. There appears to be a case for expecting new viral strains to emerge over the coming months.”
Magnetic Field Factor
We should also consider that the lowest interplanetary magnetic field values are recorded. Weakening in the Earth’s magnetic field also has an influence here. Virions, phages, bacteria and other microorganism also weaken the interplanetary magnetic field and inevitably help electrically charged new pathogens reach the surface of the Earth easily. Low or zero magnetic fields bring mutations as well. Although experts do not especially claim that Coronavirus stems from Solar Minimum, they tell that the low magnetic field caused by the decrease in the number of sunspots may engender emanation of new viruses.
As I stated in the book Başlangıç 2020, “The reason for the changes in climate and economics or the spiritual changes we observe nowadays, is not only the changing magnetic fields but also the increasing number of cosmic rays. As the magnetic field of the Earth weakens rapidly, we are less protected from the harmful rays coming from the outer space.”
As I also mentioned in the same book, “The changes in the intensity of the Earth’s magnetic field may also be regional and bring changes related to the health of the people living in certain places of the world. In 2015, the Zika virus outbreak began in Mexico when the magnetic fields there weakened strikingly. We may conclude that the virus attack was seen because solar activity decreased, magnetic field is weakened and so harmful rays and other particles from outer space reached the lower layers of our atmosphere more effectively. In other words, the systematic increase of the ZIKA attack cosmic rays seems to be related to low solar activities and consequently weakening magnetic field intensity. It is a warning for us for the future pandemics. That means, even if a solution is found for Coronavirus, other viruses and pandemics may be in our agenda in the near future. We must be prepared for this since we are in a period of time when the solar activities decrease and the magnetic field weakens.”
I would like to share a paragraph I wrote for the book “Başlangıç 2020”, a co-authored book in Turkish: “We will experience a Venus-Sun inferior conjunction on June 3, 2020. Venus will be transiting in Gemini, which is associated with the lungs and respiratory tracks in medical astrology. Gemini is associated with breathing and it is also the sign, which gives quick reactions, so it indicates spasmodic respiratory disorders and especially the diseases of the upper lobes of the lungs. Gemini is also associated with travelling. In June, during Venus transit in Gemini, many people will probably be on vacation. Tokyo Olympics is one of the biggest organizations where numerous people will gather in the summer of 2020. Such crowded places may be dangerous in terms of air-borne diseases. So, special attention should be paid.” After the book has been published, Tokyo Olympics have been cancelled. It was absolutely the right decision! Various activities where lots of people attend including sport activities, concerts, and congresses have all been cancelled.
We should also be careful about Coronavirus threat during Venus retrograde in Gemini. Being over optimistic about the developments and increase of journeys may bring losses. The number of infested people and the number of hospitalization may increase. Therefore, we should attach special importance to isolation and keep in quarantine between the second half of the May and the end of June, we should not travel unless it is obligatory, we should not remain in crowded places and we should not be in face-to-face communication with the others and care about social distancing.
As I stated in my previous article, Jupiter-Pluto conjunction, that occur in every 13 years, which was also active in some of the previous pandemics, were in exact conjunction on April 5, 2020. These two planets will be conjoined two times this year; one on June 30, and the other on November 13. As a result, although we will experience a decline in the severity of the outbreak in the summer months, we may expect a second wave of outbreak in fall, especially in November!
Eclipses in Gemini and Sagittarius
Eclipses in Gemini and Sagittarius are associated with respiration, communication, circulation and journeys. The outbreak of coronavirus may continue by the end of 2021. Additionally, we will have an eclipse on Cancer 0° on June 21 which will bring important developments about the whole world. If we look back to the solar eclipse, which occurred in 2001 on the same sign and same degree, we can see that the Twin Towers were attacked on September of that year. According to the ancient astrologers, the sign of our Earth is Cancer and the eclipses on 0 degree of Cancer/Capricorn axis are the signals of events and developments which have impacts on the whole humanity. This eclipse will remind us that WE ARE A BIG FAMILY.
Mars-Saturn & Jupiter-Saturn Conjunctions in Aquarius
In Traditional Astrology, the conjunctions of these planets, especially the sign where the conjunction takes place is extremely important. According to Sadullah al-Ankarawi, a 19th century Ottoman astrologer, plague and deaths increase all over the world during Saturn transits in Aquarius. Mars-Saturn conjunction in Aquarius brings plague and other epidemics. We had Mars-Saturn conjunction in Aquarius on April 1, 2020. The health authorities have been telling that we were in the most difficult period of Covid-19 pandemics around the days of that conjunction. On April 5 2022, we will have another Mars-Saturn conjunction in Aquarius. So, we will still be under the test of epidemics as stated in ancient texts. Saturn will be transiting in Aquarius until March 7, 2023.
SUMMARY & CONCLUSION
The main actors of the recent pandemics, especially the latest outbreak of Covid-19, which have started as of the end of 2019, seem to be the decrease in solar activities, weakening of the magnetic field and Venus-Sun inferior conjunction which we have not experienced yet. Jupiter-Saturn conjunction on December 21, 2020 is also related to changes in the magnetic field and sunspot cycles. As it will be the first conjunction of these two planets in Air signs, it is called the Great Mutation. Jupiter-Saturn conjunctions have a great importance in astrology.
- In the months following the inferior conjunction of Venus, the outbreak of virus may make an attack. November and December of 2020 are remarkable in this context.
- As the magnetic field is getting weaker and Solar Minimum is deepening, it is obvious that we are in a risky period not only due to the outbreak of Covid-19 but also in terms of outbreaks of other viruses. Existing virus may also mutate.
- Jupiter-Pluto conjunctions are linked with great outbreaks as I mentioned in my previous article. The last conjunction of these two planets will occur in November this year. Then, the influences of this conjunction will be decreasing. Jupiter-Pluto conjunctions indicate important developments in the health sector and in other scientific fields.
- Lunar Nodes and eclipses in Gemini/Sagittarius axis will come to an end as of January 18, 2022. You may see the details in my previous article.
- Ancient astrologers state Jupiter-Saturn conjunctions, the next one, which will occur on December 21, 2020, are associated with plague and other epidemics. Saturn, which is temporarily in Aquarius now, will return to Capricorn on July 2 and will then enter in Aquarius again on December 17, 2020. Jupiter will also be in Aquarius on December 19, 2020. Together with this transit, we may expect some big developments in medical field. Around the New Moon on February 11, 2021, some huge developments will be experienced and an important step for the future will be taken.
- Saturn will stay in Aquarius until March 7, 2023. On April 5, 2022, we will experience the second Mars-Saturn conjunction in Aquarius, which indicates plague, fatal outbreaks and mass disasters.
Consequently, it is obvious that Covid-19 will be on the scene in April and May this year. However, we should not relax in June. We should follow the instructions and rules and be strictly cautious. Otherwise, the number of deaths on Earth may increase seriously. Developments about vaccine and medication are on the horizon. We should be hopeful about the future, we should be in cooperation and we should fight together against this common enemy. If we are careful about the precautions, then we may sigh with relief in summer months. However, we should be cautious about the possibility of another wave of outbreak in autumn.
We are in a period where we will realize what the ancients meant with the term Great Mutation. 2021 will be extremely important within this context. We are at the edge of a huge change as the whole of humanity. Through the developments in science, technology, data processing and education, our lives will transform into a new form which is highly different than today.
Let’s hope for the best!
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Founder of AstroArt School of Astrology (ASA) | 0.804522 | 3.689467 |
Using NASA’s Spitzer and Swift missions, as well as the Belgian AstroLAB IRIS observatory, astronomers reveal new details on one of the most mysterious stellar objects.
Called KIC 8462852, also known as Boyajian’s Star, or Tabby’s Star, the object has experienced unusual dips in brightness — NASA’s Kepler space telescope even observed dimming of up to 20 percent over a matter of days. In addition, the star has had much subtler but longer-term enigmatic dimming trends, with one continuing today. None of this behavior is expected for normal stars slightly more massive than the Sun. Speculations have included the idea that the star swallowed a planet that it is unstable, and a more imaginative theory involves a giant contraption or “megastructure” built by an advanced civilization, which could be harvesting energy from the star and causing its brightness to decrease.
A new study using NASA’s Spitzer and Swift missions, as well as the Belgian AstroLAB IRIS observatory, suggests that the cause of the dimming over long periods is likely an uneven dust cloud moving around the star. This flies in the face of the “alien megastructure” idea and the other more exotic speculations.
The smoking gun: Researchers found less dimming in the infrared light from the star than in its ultraviolet light. Any object larger than dust particles would dim all wavelengths of light equally when passing in front of Tabby’s Star.
“This pretty much rules out the alien megastructure theory, as that could not explain the wavelength-dependent dimming,” said Huan Meng, at the University of Arizona, Tucson, who is lead author of the new study published in The Astrophysical Journal. “We suspect, instead, there is a cloud of dust orbiting the star with a roughly 700-day orbital period.”
Why Dust is Likely
We experience the uniform dimming of light often in everyday life: If you go to the beach on a bright, sunny day and sit under an umbrella, the umbrella reduces the amount of sunlight hitting your eyes in all wavelengths. But if you wait for the sunset, the sun looks red because the blue and ultraviolet light is scattered away by tiny particles. The new study suggests the objects causing the long-period dimming of Tabby’s Star can be no more than a few micrometers in diameter (about one ten-thousandth of an inch).
From January to December 2016, the researchers observed Tabby’s Star in ultraviolet using Swift, and in infrared using Spitzer. Supplementing the space telescopes, researchers also observed the star in visible light during the same period using AstroLAB IRIS, a public observatory with a 27-inch-wide (68 centimeter) reflecting telescope located near the Belgian village of Zillebeke.
Based on the strong ultraviolet dip, the researchers determined the blocking particles must be bigger than interstellar dust, small grains that could be located anywhere between Earth and the star. Such small particles could not remain in orbit around the star because pressure from its starlight would drive them farther into space. Dust that orbits a star, called circumstellar dust, is not so small it would fly away, but also not big enough to uniformly block light in all wavelengths. This is currently considered the best explanation, although others are possible.
Collaboration with Amateur Astronomers
Citizen scientists have had an integral part in exploring Tabby’s Star since its discovery. Light from this object was first identified as “bizarre” and “interesting” by participants in the Planet Hunters project, which allows anyone to search for planets in the Kepler data. That led to a 2016 study formally introducing the object, which is nicknamed for Tabetha Boyajian, now at Louisiana State University, Baton Rouge, who was the lead author of the original paper and is a co-author of the new study. The recent work on long-period dimming involves amateur astronomers who provide technical and software support to AstroLAB.
Several AstroLAB team members who volunteer at the observatory have no formal astronomy education. Franky Dubois, who operated the telescope during the Tabby’s Star observations, was the foreman at a seat belt factory until his retirement. Ludwig Logie, who helps with technical issues on the telescope, is a security coordinator in the construction industry. Steve Rau, who processes observations of star brightness, is a trainer at a Belgian railway company.
Siegfried Vanaverbeke, an AstroLAB volunteer who holds a Ph.D. in physics, became interested in Tabby’s Star after reading the 2016 study, and persuaded Dubois, Logie and Rau to use Astrolab to observe it.
“I said to my colleagues: ‘This would be an interesting object to follow,'” Vanaverbeke recalled. “We decided to join in.”
University of Arizona astronomer George Rieke, a co-author on the new study, contacted the AstroLAB group when he saw their data on Tabby’s Star posted in a public astronomy archive. The U.S. and Belgium groups teamed up to combine and analyze their results.
While study authors have a good idea why Tabby’s Star dims on a long-term basis, they did not address the shorter-term dimming events that happened in three-day spurts in 2017. They also did not confront the mystery of the major 20-percent dips in brightness that Kepler observed while studying the Cygnus field of its primary mission. Previous research with Spitzer and NASA’s Wide-field Infrared Survey Explorer suggested a swarm of comets may be to blame for the short-period dimming. Comets are also one of the most common sources of dust that orbits stars, and so could also be related to the long-period dimming studied by Meng and colleagues.
Now that Kepler is exploring other patches of sky in its current mission, called K2, it can no longer follow up on Tabby’s Star, but future telescopes may help unveil more secrets of this mysterious object.
“Tabby’s Star could have something like a solar activity cycle. This is something that needs further investigation and will continue to interest scientists for many years to come,” Vanaverbeke said.
PDF Copy of the Study: Extinction and the Dimming of KIC 8462852
Source: Elizabeth Landau, Jet Propulsion Laboratory | 0.858992 | 4.008733 |
A century of galaxy discrimination revealed by giant European astronomy survey
21 December 2017
A huge European astronomy survey, whose results are released today (21 December 2017), has revealed that the view of the Universe provided by traditional optical telescopes is seriously biased.
The Herschel ATLAS (H-ATLAS) was a survey carried out by an international team led by researchers at Cardiff University with European Herschel Space Observatory in the far-infrared waveband, which consists of electromagnetic waves with wavelengths 200 times greater than optical light.
Although Herschel stopped observing in 2013, the Herschel-ATLAS team has spent the last five years analysing their results, and today they released their final images and catalogues, which consist of half-a-million galaxies emitting far-infrared radiation. While the optical light from galaxies is starlight, the far-infrared radiation is from interstellar dust, tiny solid grains of material between the stars.
Galaxies, assemblies of stars ranging from 40,000 to thousand billion stars (ours contains about one billion) are the basic building blocks of our Universe. Since they were discovered about a century ago, most of what we know about them has come from optical telescopes. However, when looked at in far-infrared light, the galaxy population looks very different.
Initially, the team used their results to measure how much dust there is in galaxies today. Cardiff University PhD student Rosie Beeston who led this work said: “Before, astronomers were trying to understand how much dust there is billions of light years away but didn’t really have a handle on how much dust resides in our own astronomical backyard because only a couple of hundred measurements existed. Now we’ve created a census of dust in over 15,000 galaxies.”
Puzzlingly, the team also found a mysterious class of galaxy with lots of gas and a bigger ratio of dust to star mass than any other type of galaxy. Dubbed BADGERS (Blue and Dusty Gas Rich Galaxies), these galaxies are deeply mysterious, since the huge amounts of dust should hide most of the optical light, and the dust is also very cold.
Dr Loretta Dunne, a research fellow at the University’s School of Physics and Astronomy, was amazed to discover these odd new galaxies: “I remember checking the optical images of our brightest 300 galaxies and being amazed that they were mostly these really messy looking blue galaxies with no obvious signs of dust. It was totally not at all what I was expecting to see, and the funny thing was I having this eureka moment in Sydney airport on my way to an H-ATLAS meeting in Cardiff.”
‘Green valley’ galaxies
Another discovery made by the team has overturned astronomers’ ideas about how galaxies evolve. All current theories of how galaxies evolve are based on the fundamental assumption that there are two classes of galaxy: galaxies in which stars are actively forming and ‘quiescent galaxies’ in which star formation has essentially stopped. This assumption is based on decades of optical surveys, which have found that most galaxies are either blue (star-forming) or red (quiescent). The existence of these two classes means that all theories need to include a catastrophic process that suddenly (in cosmic terms) converts a star-forming galaxy into a quiescent galaxy.
Most of the galaxies detected in the Herschel ATLAS, however, fall in the ‘green valley’ between the red and the blue galaxies. According to Professor Steve Eales, of the University’s School of Physics and Astronomy: “This discovery has overturned all the current theories for how galaxies evolve. Our results show that there really is only a single galaxy class...”
The catalogues and images released by the team today will be a treasure trove for the worldwide community of astronomers. Apart from revolutionising our view of galaxies, the catalogues contain galaxies ranging from ones nearby to ones being seen only a billion years after the big bang, tens of thousands of galaxies magnified by ‘gravitational lensing’, and even tiny clouds of dust in our own galaxy. Since there is no similar mission on the drawing board for either the European Space Agency or NASA, the results from the survey will be a fundamental resource for astronomers for decades to come.
Dr Elisabetta Valiante, also of the School, who led the team that produced the galaxy catalogues: “The H-ATLAS survey is a milestone in the history of far-infrared astronomy and I expect it to be a reference for the next generation of researchers studying the formation of stars and galaxies.” | 0.853465 | 3.788776 |
The first-ever black hole image generated using a machine learning algorithm created a huge buzz around the globe and proved to be a major scientific discovery. This algorithm, called CHIRP which stands for ‘Continuous High-resolution Image Reconstruction using Patch priors’ showed the power of machine learning in producing an image of a black hole, something which would have otherwise not been possible.
Now the next big thing is making a black hole movie. There has been research going on that uses the wonders of ML to create a black hole movie. The woman working behind the black hole movie is Lia Medeiros, a physicist, astrophysicist and a National Science Foundation fellow.
How Will ML Algorithm Make A Movie?
Making a movie would require getting information about what happens in and around the black hole using ML algorithms. This means that a time series of images has to be put together to obtain this movie. It is going to tell how the image of the black hole changes as a function of time.
The black hole chosen to obtain this movie lies at the centre of a star called Saggitarrius A* or Sgr A*. This star is about 26,000 light years away from the Event Horizon Telescope (EHT). Sgr A* has an event horizon with a radius of about 7.9 million miles, making it about 18 times the Sun’s diameter. This black hole exerts a tremendous amount of gravitational pull on anything that crosses its event horizon.
Such a far away object would need robust images to make a movie out of the black hole at the centre of it, which is why the EHT is used, which was also used in case of obtaining the black hole image.
Key Requirements To Accomplish The Task
A large amount from the EHT, which formed an array of telescopes throughout the globe, is used to obtain the movie. The black hole image captured did not have a direct image generated but they were pieces or petabytes of raw data consisting of the radio waves originating from the ring-shaped silhouette of a black hole.
El Gato, a short form of Extremely LarGe Advanced TechnOlogy cluster is a high-performance computer by the National Science Foundation and the University of Arizona. This computer has special hardware to achieve the high performance that it delivers. It has NVIDIA K20X GPUs and Intel Xeon Phi 5110p Coprocessors. The system is designed around Intel Ivy Bridge CPUs, large amounts of memory per node (256GB/node), and FDR Infiniband. It is connected using an FDR Infiniband speed to a DataDirect Networks SFA 12K petabyte-scale storage server. This system takes a lot of data and mathematically transforms the input data into an image.
The method will involve creating simulations and using them as training data for the algorithm which will eventually be used to create a time series of the black hole images, which is what is finally wanted. But this collected data is not enough to create a complete picture of the black hole and then make a movie out of it. There is a lot of missing data which has to be filled to complete the image. This is where the ML algorithm is needed.
Machine Learning Algorithm:
The ML algorithm containing datasets, which is nothing but the images from EHT, may have some information missing. This missing information will be fed to the algorithm. This will also contain simulations. Both the images and the simulations will be used for training the ML model, helping Medeiros in finally creating the time series of images.
The ML algorithm that goes behind making the first ever black hole movie is based on the Principle Component Analysis (PCA). PCA is a dimensionality reduction method used to reduce the dimensionality of a large dataset to a small dataset. It is commonly used in the analysis and representation of complex data to reduce a large set of variables to a small set. This small set contains the most information about the large reduce set. PCA could also be seen as an algebra operation that contains a lot of ML applications, which helps in reducing the data into its principal components. Its applications lie in areas where data analysis and the predictive tool is involved using large datasets.
For the final movie production, PCA algebra operation will be added to the ML algorithm that Medeiros is making. This algorithm is going to learn from the data that it will be fed with. The training set of the ML algorithm will be able to produce 10 to 20 images. The training set can be used to identify images that will act like building blocks of a blackhole image. These building blocks would be put together make an image with the algorithm that will fill the parts of what they do not have the data for. This way, a complete image could be obtained. This new ML algorithm could give the world its first ever black hole movie.
Quantum physics and GTR, two of the most important aspects of physics, when clubbed together do not give us the Physics that we have known so far. Black holes form the perfect test bed to study these together as it is large in terms of mass like in GTR and at the same time has an infinite density at its centre governed Quantum physics.
All these machine learning-guided physics experiments are here to show how correct or incorrect is Einstein’s GTR. Black hole movies could also lead us to the understanding of how quantum mechanics interact with GTR. They can help with the information needed to check these theories and help with bigger discoveries. | 0.808175 | 3.414194 |
Brown dwarfs are an interesting sort, and can only be classified in a kind of cosmic periphery between stars and planets: they are too small to be called stars and too large to be called planets. And astronomers haven’t been sure whether they form like stars, from the gravitational collapse of gas clouds, or if they form like planets, where rocky material comes together until it grows massive enough to draw in nearby gas. But now strong evidence has been found that brown dwarfs form more like stars. Using the Smithsonian’s Submillimeter Array (SMA), astronomers detected molecules of carbon monoxide shooting outward from a brown dwarf ISO-Oph 102. This type of molecular outflows typically is seen coming from young stars or protostars. However, this object has an estimated mass of 60 Jupiters, meaning it is too small to be a star, and has therefore been classified as a brown dwarf. But this new finding means brown dwarfs are more like stars than planets.
Typically, brown dwarfs have masses between 15 and 75 Jupiters, and the theoretical minimum mass for a star to sustain nuclear fusion is 75 times Jupiter. As a result, brown dwarfs are sometimes called failed stars. A star forms when a cloud of interstellar gas draws itself together through gravity, growing denser and hotter until fusion ignites. If the initial gas cloud is rotating, that rotation will speed up as it collapses inward, much like an ice skater drawing her arms in. In order to gather mass, the young protostar must somehow shed that angular momentum. It does so by spewing material in opposite directions as a bipolar outflow.
A brown dwarf is less massive than a star, so there is less gravity available to pull it together. As a result, astronomers debated whether a brown dwarf could form the same way as a star. Previous observations provided hints that they could. The serendipitous discovery of a bipolar molecular outflow at ISO-Oph 102 offers the first strong evidence in favor of brown dwarf formation through gravitational collapse.
As might be expected, the outflow contains much less mass than the outflow from a typical star: about 1000 times less, in fact. The outflow rate is also smaller by a factor of 100. In all respects, the molecular outflow of ISO-Oph 102 is a scaled-down version of the outflow process seen in young stars.
“These findings suggest that brown dwarfs and stars aren’t different because they formed in different ways,” said Paul Ho, an astronomer at the Harvard-Smithsonian Center for Astrophysics and director of ASIAA. “They share the same formation mechanism. Whether an object ends up as a brown dwarf or star apparently depends only on the amount of available material.”
The paper on ISO-Oph 102 will be published in the December 20 issue of the Astrophysical Journal Letters. | 0.818126 | 4.062776 |
We Can See the Universe
We Can Begin to Understand It
If there's a clear night, look outside this week. Facing south, the sky should look much like the picture below. You can tell it's winter by the winter constellations, Orion (the Hunter,) and Taurus, (the Bull) with the Pleiades on his shoulder, but also Orion's dog Canis Major, who follows Orion across the sky each winter night. The brightest star in our sky is Sirius, on Canis Major's collar.
Where you see zodiac constellations, such as Taurus, the planets, and the light where the Sun is setting, you know you are looking along the ecliptic, across the plane of our Solar System. Venus is the brightest planet nearest the Sun. Sometimes it is the morning "star" and sometimes the evening "star" depending on which side of the Sun it is on.
Canis Major the "Big Dog" (with Sirius in his collar), Orion the "Hunter", Taurus the "Bull", the planet Venus and the Pleiades
As you know, the distance from Earth to the Sun is one (AU) astronomical unit about 150,000,000 km or 8 light minutes.
An astronomical unit (AU) is the distance Sun to Earth
Neptune is 30 AU from the Sun, and takes almost 165 years to complete its orbit. Mercury, close to the Sun at only 0.4 AU, travels around the Sun every 3 months. The distance from the Sun to the Kuiper Belt is about 50 AU. Comets traveling from the Kuiper Belt or nearer, travel for under 200 years. Pluto, once considered a planet, is a Kuiper Belt object. Its orbit, which does not leave the Kuiper Belt, is about 248 Earth years.
The Solar System is mostly open space
Seeing the Kuiper Belt inside the great Oort Cloud makes our solar system seem small
The huge Oort Cloud of debris that surrounds the solar system reaches from 50,000 to 100,000 AU from the Sun. Since 1 light year equals about 63,240 AU the spherical Oort Cloud around our Solar System is about 2 light years (ly) across. Kepler's 3rd Law can give us an idea of the period of these Oort Cloud snowballs.
- P2 = A3
- P2 = (100,000)3
- P2 = 1,000,000,000,000,000
- P = 316,228 years
It may take an object in the Oort Cloud 316,228 years to orbit the Sun. Similarly Comet McNaught is expected to return in about 300,000 years.
All of these things are made up of hydrogen from the Big Bang, elements fused in stars, and compounds mostly formed in the interstellar medium and protoplanetary disks ... wherever conditions of temperature and density of atoms allowed.
We Can See the Milky Way Galaxy
When we see Earth, Venus, Moon (1.3 light seconds away), Sun (8 light minutes away) and comets, we are looking at our Solar System. When we see the stars, we are looking at our galaxy, 100,000 light years across.
The Milky Way galaxy is 100,000 light years (ly) across
Aside from dark matter and dark energy, everything in the galaxy has to do with stars: stars being born, single stars, double stars, star clusters, main sequence stars, stars swelling to become red giants as they near their end, planetary nebula or supernovae of small and large stars as they die, and the white dwarfs, neutron stars, and the black holes they collapse to become. Even the dust between the stars has been within or may become a star.
Our Sun is just one of over 100 billion stars in the Milky Way, and is located about half way out one of the spiral arms. When we see the winter stars, we are looking out, away from the center, across the Perseus arm towards the edge of our Milky Way galaxy.
The Sun is about half way out a Spiral Arm of the Milky Way
When you look at the constellation Orion, this is what you really see. Betelgeuse is an aging red giant star on Orion's shoulder. The left star in Orion's belt is Alnitak, the large hot type-O star we have seen before. Beneath Alnitak is the Horsehead Nebula, gathering dust and gas that may someday create stars. In Orion's dagger we can see the Great Orion Nebula, a starbirth nebula. Its entire light is powered by one extremely hot star. The nebula is about 1350 ly from us. The light you see tonight, left its bright center 660 AD, back in the Dark Ages.
Around the Orion and Horsehead nebulae is the giant Barnard's Loop, which remains from a supernova 2 million years ago. It has spread 300 light years across. Remnants from the Barnard Loop supernova, mixed with debris from other stars and surrounding gases, helped create the nebulae and stars that exist there today. Supernova debris would in that vicinity would have heavy enough elements to create planets, and even life.
Can you find the constellation Orion, the red giant star Betelgeuse, Horsehead Nebula, Great Orion Nebula, and Barnard's Loop curving around the Horsehead and Orion Nebula?
Alnitak and Flame Nebula
Horsehead Nebula beneath the left star in Orion's Belt may someday become a star forming nebula
True Color Orion Nebula, M42, middle star in the "knife" on Orion's Belt
Credit: Robert Gendler
But there are many many many more beautiful nebulae. To the left of Orion, almost the size of the full Moon, but too faint to see by eye, the Rosette Nebula shown below is captured in long exposure photography. It is full of small dark clouds where stars are being born now.
False color Rosette Nebula
Credit:: Hubble Space Telescope
Hydrogen in the Rosette makes it appear magenta in color if you could see it without the aid of an electronic camera. Hubble images are often color coded with emission from sulfur atoms in red, hydrogen atoms in blue, and oxygen atoms in green. Both images reveal dark globules, dust and gas gathering to become stars.
These globules will become single stars like the Sun, binary stars like Sirius in Canis Major, multiple star systems like Polaris, and small open clusters of stars of colorful stars like the Pleiades.
Sirius AB taken by Chandra in x-ray light, compared with Polaris A Ab and B in visible light
Pleiades (Seven Sisters, or Subaru), to the right of Taurus' left horn tip, is an open star cluster that has wisps of a dusty nebula
Credit: Robert Gendler
M41 star cluster in Canis Major (the heart of the "Big Dog")
Credit:: Robert Gendler
The "Double Cluster", NGC 884 and NGC 869, in Perseus
On Orion's shoulder is the red supergiant star Betelgeuse. A dying star that has expanded before its final collapse, it is one of the largest stars known. At 1000 times the Sun's diameter, if it were in our Solar System it would extend beyond Mars and enclose all the terrestrial planets.
Some 5 billion years in the future, the Sun will become a red giant when it nears its end, and expand to enclose Mars as well. Will the Earth be consumed? Perhaps not, because in its last years the Sun will lose enough mass that the Earth's orbit will increase in size. It will not matter for our descendents though. By then the Sun will be so luminous that the icy worlds of the outer solar system will melt, and the Earth's oceans will be evaporated and blown away.
Betelegeuse taken by the Hubble Space Telescope (HST)
When stars like our Sun die, they ultimately collapse to become a white dwarf star, while sending a huge cloud of gas and dust out in a beautiful planetary nebula. Elements up to iron, are fused in stars and sent out in planetary nebulae.
Just to the right of Taurus's left horn tip is the Crab Nebula, M1, about 13 light years across. The Crab nebula is a remnant from a supernova that occurred in 1054. It was recorded by the Chinese, and also by American indians who painted the event under a high ledge in Chaco Canyon, New Mexico.
Supernovae are where heaviest elements, such as gold and platinum and nickel are made in its great shock waves. The gold ring on your finger and the silver in your teeth came originally from a supernova explosion from a giant dying star. Now 13 ly across, in 2 million years it may look like Barnard's Loop and be 300 light years across !
Crab Nebula is about 12 ly across and 6500 ly away
Credit: NASA, ESA, and J. Hester
You can tell the size and how hot stars are by their color.
As previously mentioned, the reddest stars are the smallest and coolest. The bluest stars are the largest and hottest. We may see all the luminosities temperatures and colors of main sequence stars on a Hertzsprung-Russell or HR diagram.
There are, also, dying red giant stars to the upper right, and small deceased white dwarf stars to the lower left. But a spectrum of the star would be needed to keep from confusing it with a main sequence star.
Hertzsprung-Russell diagram. Each dot is a star with a known spectrum or color, and a known magnitude or luminosity. Red stars are on the right. Bright stars are at the top.
Oddly enough the larger, bluer, stars have so much gravity that fusion takes place more rapidly, and they burn themselves out the quickest of all!
Extremely large stars, common in the dense early universe, would only have survived about 3 million years. Whereas the Sun should last more than 10 billion years. The small faint red stars could last thousands of billions of years.
For more precision, each letter in the spectral class or type has 10 subdivisions, from 0 to 9, 0 being the hottest and 9.9 being the coolest subdivision. The hottest (and biggest) stars would be O 0 and the coolest (and smallest) M 9.9. The Sun is G2.
Star Mass (solar masses)
MASS OF A CELESTIAL OBJECT
We can tell the mass of a star by its color and spectrum because we understand the processes they use to make the light they emit. But we can also tell mass of celestial bodies, even galaxies, by objects orbiting them.
In Kepler's 3rd Law P2 = A3 (P being the period in years, and A being the semi-major axis in AU) was discovered by watching planets in the Solar System orbit our Sun, a one solar mass star. More generally when a small object orbits something much bigger,
P2 = A3/ M
(M being the total mass in units of the Sun's mass). If we know the period and semi major axis of a system, we can find the mass of that system.
Here's how it works. If M = 2, as around a star of 2 solar masses, the formula becomes P2 = A3 / 2 which means the period squared will be cut in two. If Earth were orbiting a 2 solar mass star, it would have to travel faster to resist the increased gravitational force, and Earth's year would shortened by 1.4 (1.41x1.41 = 2). How long would Earth's year be around a 3 solar mass star if it orbited the same distance it does now around the Sun? In that case P2 = A3 / 3 . ( Hint: 1.73x1.73 = 3). That means the "year" for this Earth would be shortened by 1.73.
Suppose you know the period, the time it takes to orbit a star, and you have been able to measure its semi-major axis, half the distance across the orbit. Using a little algebra, P2 = A3 / M becomes M = A3/P2
Now you can measure the mass of a planet from the motions of its moons, the mass of a star from the motions of its planets or companion stars, or the mass of a black hole from the gases or stars swirling around it.
How to find the Mass of the Milky Way Galaxy
Here's one more, astounding, example. Let's use the orbit of the Sun around as it travels around the Milky Way to find how much mass is "holding" the Sun in its orbit. This is all the matter that is closer to the center of the galaxy than the Sun is. We use Kepler's third law and put in the Sun's distance (25,000 ly or 1.6 billion AU) from the center of the Galaxy, and the time it takes for the Sun to complete one orbit (250 million years) around the Galaxy:
A = 1.6 x 109 AU P = 250 x 106 years
M = A3/P2
M = (1.6 x 109 )3/(250 x 106)2
M = 7x1010 solar masses
The mass of the Milky Way Galaxy, inside the orbit of the Sun, is about 70 billion solar masses. This includes all the stars, the nebulae, and that mysterious dark matter you may have heard about. We will see later that, including stars and matter farther out than we are, the mass of the galaxy is at least 100 billion times the mass of the Sun!
(In case you want to know: The distance to the center of the Milky Way is found by measuring the globular clusters that surround its center and taking the average distance to the center of their distribution. The time to orbit the galaxy is known from the speed of the Sun measured by redshifts to surrounding galaxies, and dividing it into the circumference of its orbit, which is simply C=2πR, where R is nearly A.)
OTHER GALAXIES NEAR AND FAR
Our galaxy is 100,000 ly across. Beyond our galaxy are other galaxies, all with colorful stars, starbirth nebulae, star clusters, aging red giants, stars dying in planetary nebulae, and supernova remnants. The nearest companion galaxies are the Large and Small Magellanic Clouds, 160,000 and 200,000 light years away respectively.
Milky Way with Large and Small Magellanic Clouds to the right as seen from the southern hemisphere. Comet McNaught is to the lower right. The comet is in our solar system. The stars are in our galaxy. The Large and Small Magellanic Clouds are nearby galaxies outside our Milky Way galaxy, about 160,000 and 200,000 ly away respectively.
The Large Magellanic Cloud is the fourth largest galaxy in our Local Group of galaxies. It appears to be irregular in shape, with a bar of old red stars.
Large and Small Magellanic Clouds
All galaxies contain stars and star clusters. Galaxies where stars are still being formed have beautiful starbirth nebulae like this one in the Small Magellanic cloud.
Starbirth nebula in the Small Magellanic Cloud
and Supernova remnants like this one in the Large Magelanic Cloud.
Supernova remnant in the Large Magellanic Cloud
The first, second, and third largest galaxies in our Local Group are our Milky Way, the Andromeda galaxy, and the Triangulum galaxy, all of which are spiral galaxies with black holes at their centers.
M31, The Andromeda Galaxy, 2 million ly away, is the sister galaxy to and resembles the Milky Way. Notice its smaller companions.
Another famous galaxy is M51, the Whirlpool galaxy, near the tip of Ursa Major's tail, 23 million ly away.
M51, The Whirlpool Galaxy, is 23 millioin ly away.
And beyond them are billions of other galaxies and clusters of galaxies.
Hickson Galaxy Group
And still further away we see gamma ray bursts from giant stars exploding in the early Universe, and quasars where black holes are gobbling mass in the centers of young galaxies. Since the light we see from galaxies 10 billion light years away has taken 10 billion years to reach us, that means we are seeing galaxies as they appeared 10 billion years ago. In these images you are looking back in time 10 billion years!
Galaxies billions of light years away in the Hubble Deep Field image
Even further away there are more galaxies.
gal ultra deep
Galaxies 14 Billion Light Years Away, as seen by Hubble's Ultra Deep Field
There were hundreds of bright galaxies forming 14 billion years ago, 900 million years after the Big Bang. BUT researchers looking further into the past, 700 million years after the Big Bang found only one. Something must have happened to create the brighter galaxies that did not exist in earlier times.
It has been 400 years since Galileo first turned his telescope to the sky and saw Jupiter's moons.
Jupiter and its moons
Jupiter and its moons as Galileo may have seen it.
In 1610. Galileo used his telescope and logic to expand our view of the cosmos by demonstrating that the Earth was not at the center of the Universe. When he viewed these satellites, he saw them as they were 30 minutes earlier, the time it takes for light from Jupiter to reach us. Today we look back 14 billion years, using the largest telescopes in space and on Earth, giving us a window to the very beginning of time itself. | 0.92929 | 3.331142 |
NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has provided the first optical images of ice and other frozen volatile materials within permanently shadowed craters near Mercury’s north pole. The images not only reveal the morphology of the frozen volatiles, but they also provide insight into when the ices were trapped and how they’ve evolved, according to an article published October 15 in the journal, Geology.
Two decades ago, Earth-based radar images of Mercury revealed the polar deposits, postulated to consist of water ice. That hypothesis was later confirmed by MESSENGER through a combination of neutron spectrometry, thermal modeling, and infrared reflectometry. “But along with confirming the earlier idea, there is a lot new to be learned by seeing the deposits,” said lead author Nancy Chabot, the Instrument Scientist for MESSENGER’s Mercury Dual Imaging System (MDIS) and a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.
Beginning with MESSENGER’s first extended mission in 2012, scientists launched an imaging campaign with the broadband clear filter of MDIS’s wide-angle camera (WAC). Although the polar deposits are in permanent shadow, through many refinements in the imaging, the WAC was able to obtain images of the surfaces of the deposits by leveraging very low levels of light scattered from illuminated crater walls. “It worked in spectacular fashion,” said Chabot.
The team zeroed in on Prokofiev, the largest crater in Mercury’s north polar region found to host radar-bright material. “Those images show extensive regions with distinctive reflectance properties,” Chabot said. “A location interpreted as hosting widespread surface water ice exhibits a cratered texture indicating that the ice was emplaced more recently than any of the underlying craters.” | 0.862424 | 3.509809 |
NASA PR — PASADENA, Calif. — NASA’s Dawn spacecraft has returned the first close-up image after beginning its orbit around the giant asteroid Vesta. On Friday, July 15, Dawn became the first probe to enter orbit around an object in the main asteroid belt between Mars and Jupiter.
The image taken for navigation purposes shows Vesta in greater detail than ever before. When Vesta captured Dawn into its orbit, there were approximately 9,900 miles (16,000 kilometers) between the spacecraft and asteroid. Engineers estimate the orbit capture took place at 10 p.m. PDT.
Vesta is 330 miles (530 kilometers) in diameter and the second most massive object in the asteroid belt. Ground- and space-based telescopes have obtained images of Vesta for about two centuries, but they have not been able to see much detail on its surface.
“We are beginning the study of arguably the oldest extant primordial surface in the solar system,” said Dawn principal investigator Christopher Russell from the University of California, Los Angeles. “This region of space has been ignored for far too long. So far, the images received to date reveal a complex surface that seems to have preserved some of the earliest events in Vesta’s history, as well as logging the onslaught that Vesta has suffered in the intervening eons.”
Vesta is thought to be the source of a large number of meteorites that fall to Earth. Vesta and its new NASA neighbor are currently approximately 117 million miles (188 million kilometers) away from Earth. The Dawn team will begin gathering science data in August. Observations will provide unprecedented data to help scientists understand the earliest chapter of our solar system. The data also will help pave the way for future human space missions.
After traveling nearly four years and 1.7 billion miles (2.8 billion kilometers), Dawn also accomplished the largest propulsive acceleration of any spacecraft, with a change in velocity of more than 4.2 miles per second (6.7 kilometers per second), due to its ion engines. The engines expel ions to create thrust and provide higher spacecraft speeds than any other technology currently available.
“Dawn slipped gently into orbit with the same grace it has displayed during its years of ion thrusting through interplanetary space,” said Marc Rayman, Dawn chief engineer and mission manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “It is fantastically exciting that we will begin providing humankind its first detailed views of one of the last unexplored worlds in the inner solar system.”
Although orbit capture is complete, the approach phase will continue for about three weeks. During approach the Dawn team will continue a search for possible moons around the asteroid; obtain more images for navigation; observe Vesta’s physical properties; and obtain calibration data.
In addition, navigators will measure the strength of Vesta’s gravitational tug on the spacecraft to compute the asteroid’s mass with much greater accuracy than has been previously available. That will allow them to refine the time of orbit insertion.
Dawn will spend one year orbiting Vesta, then travel to a second destination, the dwarf planet Ceres, arriving in February 2015. The mission to Vesta and Ceres is managed by JPL for the agency’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Ala.
UCLA is responsible for Dawn mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are part of the mission’s team.
To view the image and obtain more information about the Dawn mission, visit: | 0.86899 | 3.517809 |
Spiral galaxy NGC 1232
This spectacular image of the large spiral galaxy NGC 1232 was obtained on September 21, 1998, during a period of good observing conditions. It is based on three exposures in ultra-violet, blue and red light, respectively. The colours of the different regions are well visible : the central areas contain older stars of reddish colour, while the spiral arms are populated by young, blue stars and many star-forming regions. Note the distorted companion galaxy on the left side, shaped like the greek letter "theta".
NGC 1232 is located 20º south of the celestial equator, in the constellation Eridanus (The River). The distance is about 60 million light-years, but the excellent optical quality of the VLT and FORS allows us to see an incredible wealth of details. At the indicated distance, the edge of the field shown corresponds to about 200,000 light-years, or about twice the size of the Milky Way galaxy.
The image is a composite of three images taken behind three different filters: U (360 nm; 10 min), B (420 nm; 6 min) and R (600 nm; 2:30 min) during a period of 0.7 arcsec seeing. The field shown measures 6.8 x 6.8 arcmin. North is up; East is to the left.
About the Image
|Release date:||23 September 1998|
|Size:||10027 x 10105 px|
About the Object
|Type:||Local Universe : Galaxy : Type : Spiral|
|Distance:||60 million light years|
|Position (RA):||3 9 45.54|
|Position (Dec):||-20° 34' 46.50"|
|Field of view:||6.78 x 6.83 arcminutes|
|Orientation:||North is 0.1° left of vertical|
Colours & filters
|420 nm||Very Large Telescope|
|360 nm||Very Large Telescope|
|600 nm||Very Large Telescope| | 0.830178 | 3.226624 |
A team of astrophysicists from Harvard, Princeton and the University of Michigan have released findings from a study in which they explain that water worlds have water supplies which they may not be able to support for long periods of time, news which could alter scientists’ thinking about the idea of habitable planets.
Findings from the study, titled “The Dehydration of Water Worlds Via Atmospheric Losses”, was published in last month’s Astrophysical Journal of Letters. Briefly, the study examines the rate of exoplanet water ion loss, provided through computer simulations of the conditions of a water world.
But first, how did we come to this point of focus in the body of research?
With the surge in space technology and space travel capabilites we’ve experienced in the 21st century, combined with the scramble for resources that is affecting life in every corner of the globe, many have begun to look beyond the borders of our planet for future life-sustaining possibilities.
This has given NASA’s work on charting the planets in our galaxy more renewed meaning. As of now, NASA has confirmed the existence of 3,545 exoplanets, going to great lengths to classify everything from the atmospheric conditions, to the precipitation patterns of exoplanets. This research is an important piece in this monumental task of “building an understanding of how many and what kinds of planetary systems exist in the galaxy.”
There is a fine distinction between an exoplanet and a habitable zone. Also known as the “Goldilocks Zone”, as the name suggests, it indicates exoplanets that have a common set of characteristics for being habitable: the distance from its respective star makes it not too hot, and not too cold for supporting liquid water, a fundamental ingredient for sustaining life.
Within this paradigm are water worlds, planets which are composed of up to 50 percent water, producing surface oceans with staggering depths that reach hundreds of kilometers to the core.
Led by Chuanfei Dong from the Department of Astrophysical Sciences at Princeton University, the team conducted computer simulations that took into account what kind of atmospheric conditions water worlds would be subject to.
"It is fair to say that the presence of an atmosphere is perceived as one of the requirements for the habitability of a planet. Having said that, the concept of habitability is a complex one with myriad factors involved. Thus, an atmosphere by itself will not suffice to guarantee habitability, but it can be regarded as an important ingredient for a planet to be habitable," said Dong.
Through observing the combined effects of coronal mass injections, atmospheric ionization and stellar magnetic fields, towards G-type and M-type stars—the Sun and Proxima Centauri among them—the team could develop a model that came close to explaining the life cycle of an exoplanet:
"We developed a new multi-fluid magnetohydrodynamic model. The model simulated both the ionosphere and magnetosphere as a whole.
The findings revealed, however, that planets based around M-type stars are more unpredictable:
"Our results indicate that the ocean planets (orbiting a Sun-like star) will retain their atmospheres much longer than the Gyr timescale as the ion escape rates are far too low...In contrast, for exoplanets orbiting M-dwarfs, they could have their oceans depleted over the Gyr timescale due to the more intense particle and radiation environments that exoplanets experience in close-in habitable zones.”
As Dr. Dong indicates future projects that will be carried out:
"Given the importance of atmospheric loss on planetary habitability, there has been a great deal of interest in using telescopes such as the upcoming James Webb Space Telescope (JWST) to determine whether these planets have atmospheres and, if so, what their composition are like.”
These are all signs indicating that efforts towards an expanded understanding of exoplanets and the evolution of planets in our Solar System are being actively undertaken. | 0.907602 | 3.674899 |
Hubble's Law & Constant16.5 - Be able to use the relationship between distance and redshift of distant galaxies (Hubble’s law) including the formula:
v = H0d
where v is the radial velocity of the recession of the galaxy, H0 is the Hubble constant and d is the distance of the galaxy from Earth.
16.6 - Understand the estimation of the age and size of the Universe using the value of the Hubble constant
So far we have looked at evidence for the expanding Universe. Not until the early 20th century did scientists realise that 'spiral nebula' were actually different galaxies and not part of ours. Georges Lemaître was one of the most prominent of 20th century astronomers and Edwin Hubble developed his theories.
Hubble proposed there was a relationship between the distance to galaxies to their redshift (or receding velocity). In other words how fast a galaxy moved was in proportion to its distance.
This is Hubble's Law - v=H0D
v = recession velocity
H0 = Hubble constant
D = distance to galaxy (mega parsec - Mpc)
Velocity is taken by measuring the galaxy over a period of time
We can calculate the distance to nearby galaxies by knowing their apparent and absolute luminosity.
To do this Hubble needed a constant of proportionality - the Hubble constant.
This is a special measurement to astronomers, as it means they can measure the age of the Universe.
Different measurements have been made, notably by the Hubble Space Telescope (HST) and Wilkinson Microwave Anisotropy Probe (WMAP). Most past measurements have been values between 50 and 100 Mpc. HST measured 74.2 ± 3.6 (km/s)/Mpc in 2009.
If the number is too high we find stars older than the Universe, and if it is too low there is not enough matter in the Universe to account for it. The constant therefore supports the Big Bang theory.
There are two areas on which scientists cannot yet agree:
- An accurate measurement everyone can agree on
- Knowing if the constant is constant and always has been that value.
The implication for the Law is that the Universe is expanding. Remember however that groups of galaxies can be gravitationally bound (like ours), so this does not necessarily apply.
New name for the constant
In 2018 the law was renamed as the Hubble-Lemaître to recognise the work of Belgian astronomer Georges Lemaître who derived the law and estimated the constant before Hubble.
- Why is the value of the Hubble constant significant?
- In a sentence, describe Hubble's Law
- What is the formula for Hubble's Law? | 0.82393 | 3.994189 |
Each year, 1,000 students come to NASA's Jet Propulsion Laboratory for internships at the place where space robots are born and science is made. Their projects span the STEM spectrum, from engineering the next Mars rover to designing virtual-reality interfaces to studying storms on Jupiter and the possibility of life on other planets. But the opportunity for students to "dare mighty things" at JPL wouldn't exist without the people who bring them to the Laboratory in the first place – the people known as mentors.
A community of about 500 scientists, engineers, technologists and others serve as mentors to students annually as part of the internship programs managed by the JPL Education Office. Their title as mentors speaks to the expansiveness of their role, which isn't just about generating opportunities for students, but also guiding and shaping their careers.
"Mentors are at the core of JPL's mission, pushing the frontiers of space exploration while also guiding the next generation of explorers," says Adrian Ponce, who leads the team that manages JPL's internship programs. "They are an essential part of the career pipeline for future innovators who will inspire and enable JPL missions and science."
Planetary scientist Glenn Orton has been bringing students to JPL for internships studying the atmospheres of planets like Jupiter and Saturn since 1985. He keeps a list of their names and the year they interned with him pinned to his office wall in case he's contacted as a reference. The single-spaced names take up 10 sheets of paper, and he hasn't even added the names of the students he's brought in since just last year.
It makes one wonder what he could need that many students to do – until he takes out another paper listing the 11 projects in which he's involved.
"I think I probably have the record for the largest number of [projects] at JPL," says Orton, who divides his time between observing Jupiter with various ground- and space-based telescopes, comparing his observations with the ones made by NASA's Juno spacecraft, contributing to a database where all of the above is tracked and producing science papers about the team's discoveries.
"Often, you get to be the first person in the world who will know about something," says Orton. "That's probably the best thing in the world. The most exciting moment you have in this job is when you discover something."
Over the years, Orton's interns have been authors on science papers and have even taken part in investigating unexpected stellar phenomena – like the time when a mysterious object sliced into Jupiter's atmosphere, sparking an urgent whodunnit that had Orton and his team of interns on the case.
Orton says his passion for mentoring students comes from the lack of mentorship he received as a first-generation college student. At the same time, he acknowledges the vast opportunities he was given and says he wants students to have them, too.
"As a graduate student, it was close to my first experience doing guided research, so I had no idea how research was communicated or conducted," says Orton of his time at Caltech, when he often worried that his classmates and professors would discover he wasn't "Nobel material." "I want to be able to work with students, which I sincerely enjoy, to instruct them on setting down a research goal, determining an approach, modifying it when things inevitably hit a bump, as well as communicating results and evaluating next steps."
For Alexandra Holloway and Krys Blackwood, the chance to provide new opportunities isn't just what drives them to be mentors, but also something they look for when choosing interns.
"I look for underdogs, students who are not representing themselves well on paper," says Holloway. "Folks from underrepresented backgrounds are less likely to have somebody guide them through, 'Here's how you make your résumé. Here's how you apply.' The most important thing is their enthusiasm for learning something new or trying something new."
It's for this reason that Holloway and Blackwood have become evangelists for JPL's small group of high-school interns, who come to the Laboratory through a competitive program sponsored by select local school districts. While less experienced than college students, high-school interns more than make up for it with perseverance and passion, says Blackwood.
"[High-school interns] compete to get a spot in the program, so they are highly motivated kids," she says. "Your results may vary on their level of skill when they come in, but they work so hard and they put out such great work."
Meet JPL Interns
Read stories from interns pushing the boundaries of space exploration and science at the leading center for robotic exploration of the solar system.
Holloway and Blackwood met while working on the team that designs the systems people use to operate spacecraft and other robotic technology at JPL – that is, the human side of robotics. Holloway has since migrated back to robots as the lead software engineer for NASA's next Mars rover. But the two still often work together as mentors for the students they bring in to design prototypes or develop software used to operate rovers and the antennas that communicate with spacecraft across the solar system.
It's important to them that students get a window into different career possibilities so they can discover the path that speaks to them most. The pair say they've seen several students surprised by the career revelation that came at the end of their internships.
"For all of our interns, we tailor the project to the intern, the intern's abilities, their desires and which way they want to grow," says Holloway. "This is such a nice place where you can stretch for just a little bit of time, try something new and decide whether it's for you or not. We've had interns who did design tasks for us and at the end of the internship, they were like, 'You know what? I've realized that this is not for me.' And we were like, 'Awesome! You just saved yourself five years.'"
The revelations of students who intern with Parag Vaishampayan in JPL's Planetary Protection group come from something much smaller in scale – microscopic, even.
Vaishampayan's team studies some of the most extreme forms of life on Earth. The group is trying to learn whether similar kinds of tough microbes could survive on other worlds – and prevent those on Earth from hitching a ride to other planets on NASA spacecraft. An internship in Planetary Protection means students may have a chance to study these microbes, collect samples of bacteria inside the clean room where engineers are building the latest spacecraft or, for a lucky few, name bacteria.
"Any researcher who finds a new kind of bacteria gets a chance to name it," says Vaishampayan. "So we always give our students a chance to name any bacterium they discover after whoever they want. People have named bacteria after their professors, astronauts, famous scientists and so forth. We just published a paper where we named a bacterium after Carl Sagan."
The Planetary Protection group hosts about 10 students a year, and Vaishampayan says he's probably used every JPL internship program to bring them in. Recently, he's become a superuser of one designed for international students and another that partners with historically black colleges and universities, or HBCUs, to attract students from diverse backgrounds and set them on a pathway to a career at the Laboratory.
"I can talk for hours and hours about JPL internships. I think they are the soul of the active research we are doing here," says Vaishampayan. "Had we not had these programs, we would not have been able to do so much research work." In the years ahead, the programs might become even more essential for Vaishampayan as he takes on a new project analyzing 6,000 bacteria samples collected from spacecraft built in JPL's clean rooms since 1975.
With interns making up more than 15 percent of the Laboratory population each year, Vaishampayan is certainly not alone in his affection for JPL's internship programs. And JPL is equally appreciative of those willing to lend time and support to mentoring the next generation of explorers.
Says Adrian Ponce of those who take on the mentorship role through the programs his team manages, "Especially with this being National Mentoring Month, it's a great time to highlight the work of our thriving mentor community. I'd like to thank JPL mentors for their tremendous efforts and time commitment as they provide quality, hands-on experiences to students that support NASA missions and science, and foster a diverse and talented future workforce."
Explore JPL’s summer and year-round internship programs and apply at: jpl.nasa.gov/intern
Career opportunities in STEM and beyond can be found at: jpl.jobs
The laboratory’s STEM internship and fellowship programs are managed by the JPL Education Office. Extending the NASA Office of STEM Engagement’s reach, JPL Education seeks to create the next generation of scientists, engineers, technologists and space explorers by supporting educators and bringing the excitement of NASA missions and science to learners of all ages.
It's Moogega Cooper's second Nerd War and she's in uncharted territory. She's been picked to play "Shadow Raven" in a fantasy story line about a "dark cult trying to resurrect an elder god." It's not that she's unaccustomed to playing a hero of sorts. As a planetary protection engineer at NASA's Jet Propulsion Laboratory in Pasadena, Calif., her job is quite literally to protect our planet and others in the solar system. It's just that this isn't her particular brand of nerd-dom -- yet.
This summer, Cooper took a break from her day job at JPL analyzing contamination risks for distant spacecraft and testing the might of extreme organisms to spend a month entrenched in a world of nerd dancing, extreme gaming and superhero debates as part of King of the Nerds, a reality competition show airing Thursday nights on TBS.
"It's a show that gets 11 nerds from across this nerd spectrum, which includes 'cosplay,' the people who do costume play, people who like comic books, scientists and engineers," said Cooper.
The nerds are pitted against each other in Survivor-style challenges, called Nerd Wars, with uniquely geeky twists, all while dealing with the often larger challenge of living under the same roof: a Pasadena, Calif., mansion dubbed "Nerdvana."
Cooper, who in the episode airing tonight is one of five finalists, says of the show that it was a test not just in smarts but in pure mental stamina. By the time the Nerd War got to her expertise in physics, "one plus one did not equal two at that point," she said.
Each of the self-proclaimed nerds have their specialties - Ivan is a video game developer, Celeste is a gamer, Danielle is an internet star and Genevieve is a Batman fangirl -- that come into play through the various team challenges and especially in the drama in Nerdvana. Cooper (who said she would avoid the drama by sneaking off to do puzzles) gets her nerd chops from her background and work in astrophysics, which has fascinated her from an early age.
"The main thing that sparked my interest in science was Carl Sagan's Cosmos," said Cooper who also spent much of her young life in Hampton, Va., near NASA's Langley Research Center. "When we would go to the library, we would rent the videos. Because he had several, we would take one every week. And because of him and Stephen Hawking, I thought, I'm going to be an astrophysicist."
Cooper was quick to turn that thought into a reality, doubling up on high school classes during her summers so she could start her undergraduate work at Hampton University at the age of 16. She later scored a place at JPL as a NASA Harriett G. Jenkins Pre-doctoral Fellow studying the use of non-equilibrium plasmas for spacecraft sterilization.
Now, at 27, she's switched to what she jokingly calls "the dark side" -- that is, engineering -- and spends her days working on various projects that involve keeping chemical or biological elements from hitching a ride on spacecraft and contaminating our planet (on returning to Earth) and other planets.
"The coolest part of my job is just having a new task to work on all the time," said Cooper. "I mean there's the same umbrella goal, but it manifests itself in either the test bed here or looking at the chemistry of a sample when it interacts with spacecraft hardware or playing with bacteria and seeing if we can kill it."
So while she's certainly got nerd cred, she also has one of the coolest jobs around. The question is whether she can survive the extreme environment of a house of nerds.
"It's kind of like moving back home, where you know there are
people that you have to live with and you can't really escape," said
Cooper. "There were times when the personalities didn't quite mesh
together completely but because we eventually got to learn about each
other and what makes us the way we are, everybody was just family." | 0.885498 | 3.159743 |
UT-Austin astronomer discovers massive black holes in two star clusters
17 September 2002
NOTE TO EDITORS: For high-resolution images to accompany this release, see: http://oposite.stsci.edu/pubinfo/pr/2002/18
AUSTIN, Texas — University of Texas at Austin astronomer Karl Gebhardt and colleagues have discovered the first black holes lurking in the hearts of two giant clusters of stars. The research provides clues to how the much-heavier "supermassive" black holes, which exist at the centers galaxies like our Milky Way, formed.
A black hole is an infinitely dense region of space, with such high gravity that not even light can escape. For many years, astronomers have known two types — supermassive black holes at the centers of large galaxies and the so-called "stellar-mass" black holes that result when a star about 10 times the Sun’s mass ends its life in a supernova explosion. Both types have been detected and measured, Gebhardt said, but a black hole with a mass in between these two has not been detected before.
Gebhardt, Michael Rich of UCLA and Luis Ho of the Carnegie Institution of Washington recently used the Earth-orbiting Hubble Space Telescope (HST) to spy on G1, a so-called "globular star cluster" in the nearby Andromeda galaxy. Globular clusters are spherical conglomerations of hundreds of thousands to millions of stars. (In contrast, a galaxy like our Milky Way contains about 200 billion stars.)
The team measured the speeds of the stars near the center of the cluster. The faster the stars move, the heavier the object they’re orbiting has to be. They deduced that G1’s central object weighs 20,000 times more than our Sun. This means it must be a black hole.
Gebhardt is also working with another group, including Roeland van der Marel of the Space Telescope Science Institute in Baltimore and others, who similarly studied the globular M15 in our own Milky Way galaxy with HST. They found that M15 harbors a black hole about 4,000 times the Sun’s mass.
"The black holes in G1 and M15 have masses in between stellar-mass and supermassive black holes," Gebhardt said. "They provide an important link that may hold the clue to how supermassive black holes form in galaxies."
Astronomers studying nearby galaxies have discovered a relationship between the size of a galaxy and the mass of the black hole at its heart: The bigger the galaxy, the more massive the black hole. Unfortunately, there are not enough small galaxies nearby to test the relationship at that end of the scale. Gebhardt said that globular star clusters are a good substitute for small galaxies. And the masses of the black holes in G1 and M15 fall in line with the black hole mass/galaxy mass relationship demonstrated in the past by Gebhardt and others.
"This evidence has major consequences about how we think black holes formed in galaxies," Gebhardt said. "Galaxies form out of a large collapsing cloud of gas. And the first things to form in that cloud are globular clusters. Those globulars are very stable, and very likely contained black holes in them at the time of their formation.
"There are two main theories about how galactic black holes form," Gebhardt said. "You could either make the black hole all at once, when the galaxy is forming, by dumping a lot of material in the middle, or you could start with a seed black hole that subsequently grows over time. The observational evidence now points to the idea that you start out with a small seed black hole."
The fact that globular clusters have these small black holes implies that they are excellent candidates to act as the seeds for the supermassive black holes that lurk in the centers of nearly all galaxies.
The G1 research will be published in an upcoming issue of The Astrophysical Journal Letters. The M15 research will be published in two articles in an upcoming issue of The Astronomical Journal.
Gebhardt is studying other globular clusters, looking for more black holes. He will also do follow-up studies of G1 and M15 at The University of Texas at Austin’s McDonald Observatory near Fort Davis.
Gebhardt is an assistant professor in the University’s Department of Astronomy. He may be reached at 512-471-1473 or via email at: [email protected].
-- END -- | 0.848988 | 3.8656 |
Galaxies are connected by faint filaments of gas. Image Credit: Joshua Borrow using C-EAGLE
Scientists have revealed the first photograph of a universe-spanning network of intergalactic filaments.
Known as the cosmic web, this previously unseen highway is made up of gigantic filaments of gas (mostly hydrogen left over from the Big Bang) which bridge the void between galaxies.
It is thought that the web contains as much as 60% of all the gas in the universe.
Actually observing these filaments directly however has long proven a challenge because they are incredibly faint and easily overshadowed by the intense glow of the galaxies around them.
Now though, scientists have finally been able to piece together the first photograph of these cosmic structures converging on a distant galaxy cluster 12 billion light years away from Earth.
This feat was achieved using the Multi Unit Spectroscopic Explorer instrument on the European Southern Observatory's Very Large Telescope in Chile.
"The main obstacle to see the filaments is their faintness," said study lead author Hideki Umehata.
"To circumvent this, one can turn to a region where the filaments are much brighter than the usual case. In this work, we focus on a core of the protocluster where a number of star-bursting galaxies illuminate the filaments." | 0.871156 | 3.500669 |
By Neha Jain
During the ice ages, ice sheets covered large parts of the Earth, unlike today, when ice sheets are found only at the poles. Our planet has been going through cycles of glacial periods (which are actually shorter periods within an ice age) featuring colder temperatures, and interglacial periods, characterized by a warmer climate, for hundreds of thousands of years.
The last deglaciation, when the Earth moved out of the glacial period, began around 20,000 years ago. At that time, carbon dioxide in the atmosphere began to rise and warm our planet by an increased greenhouse effect. Now, a new study from Antarctica shows that during that time abrupt increases in carbon dioxide in the atmosphere came from land sources, not only from the ocean as scientists had believed.
What Caused the Last Deglaciation?
One of the main factors that drove the last deglaciation period—from 20,000 to 10,000 years ago—was a change in Earth’s orbit that increased the level of solar radiation reaching the Earth during summers. The other driving factor was a rise in carbon dioxide levels in the atmosphere, which rose by about 75 parts per million (ppm). There was a corresponding rise in global temperatures of about 3.5 degrees Celsius, as well as a rise in sea levels of 130 meters, due to the melting of ice sheets.
Until now, the origin of that carbon dioxide was unclear, as was what caused carbon dioxide levels to rise in the first place. “This has emerged as one of the big mysteries in paleoclimate science over the last few decades,” says Thomas Bauska, lead researcher of the study, from Oregon State University and now a postdoctoral researcher at the University of Cambridge, UK. Most scientists believe the carbon dioxide came from the ocean surrounding Antarctica, called the Southern Ocean.
Measuring Trapped Land Carbon
The Antarctic ice sheet covers an area larger than the US and India combined. Snow falls each year on ice sheets at the poles and eventually gets compressed into ice. Tiny air pockets in the ice contain bubbles of trapped ancient air that can supply a wealth of information about the climate of thousands of years ago. Air bubbles from ice cores can show how carbon dioxide levels changed in our atmosphere during the last deglaciation, as well as its likely source.
To find out the sources of carbon dioxide, scientists measured the ratio of stable carbon isotopes, specifically the ratio of the isotopes carbon-13 to carbon-12, in air samples from ice deposited 22,000 to 11,000 years ago. Carbon from different sources has different isotopic “fingerprints.” Bauska and his team developed a device that allowed them to use large ice samples, which in turn enabled them to use a type of mass spectrometry that measures the ratios more precisely. The team’s device, known as the “cheese grater,” shaves off thin layers of ice from the samples. “We then sample the air released from the bubbles and measure the concentration of gases and their isotopic ratios,” Bauska explained to GotScience.org.
Extracting ice samples from previously drilled ice cores is tricky because the samples are very large, says Bauska. But the study was made possible when Bauska’s team fortunately discovered a section of ice on the surface of a glacier called Taylor Glacier in Antarctica where older, deeper ice was outcropped, making sampling easier.
Changing Sources of Carbon Dioxide
The team learned that during the deglacial period the rise in atmospheric carbon dioxide occurred gradually in a series of steps, with each step caused by different mechanisms and sources. During the initial phase of deglaciation, which lasted about two thousand years (from 17,600 to 15,500 years ago), carbon dioxide increased by about 35 ppm. This was characterized by a decrease in the carbon isotope ratio, which signaled that the carbon dioxide came mostly from oceanic sources, confirming what scientists had believed. In particular, the increased carbon dioxide was attributed to a weakened state of the ocean’s biological pump. The biological pump is a process in which the ocean removes carbon dioxide from the atmosphere and transports it deep into the water. Microscopic marine organisms called phytoplankton, living on the surface, take up the carbon dioxide for photosynthesis. During photosynthesis, they use the carbon dioxide to make carbohydrates and other organic compounds. The phytoplankton clump together and sink to the ocean floor, carrying the carbon (which originally came from the atmosphere) deep into the ocean. The biological pump can be weakened due to a decrease in the transport of carbon into the deep ocean.
During the next 4,000 years, atmospheric carbon dioxide rose by 40 ppm, the result mostly of a weakened biological pump, as well as rising ocean temperatures. As the ocean surface temperature rises, carbon dioxide can bubble back out into the atmosphere. Although the ocean was a source of early carbon dioxide, later there were two times—one at 16,300 and another at 12,900 years ago—when carbon dioxide levels rose rapidly by about 10 ppm, and there were abrupt changes in the carbon isotope ratios. The researchers suggest that during those two times extra carbon may have come from land sources or from rapid changes in the exchange of carbon dioxide between the oceans and the atmosphere due to greater wind speeds over the Southern Ocean.
“Quite a large portion of the CO₂ that is stored in the ocean is exhaled and inhaled around Antarctica,” explains Bauska. Large areas of sea ice during the glacial period blocked CO₂, which would have built up in the deep ocean. “If this barrier is suddenly lifted, CO₂ would escape back into the atmosphere.”
“The bulk of the CO₂ rise is still probably sourced from the ocean. The land carbon events might just be bumps along the way. However, they are very interesting because they might be telling us how sensitive the land carbon cycle is to abrupt changes in climate.”
Interestingly, the first time of rapidly rising carbon dioxide levels (16,300 years ago) coincided with a period of drought in the region that is now China. “This may be telling us that large-scale droughts can cause rapid losses of carbon stored on land,” says Bauska. At the same time, there was a small but rapid increase in methane, which may have come from rising wetlands in the southern hemisphere.
Two additional times when carbon dioxide in the atmosphere rose considerably, around 14,600 and 11,500 years ago, point to a combination of carbon sources, including rising surface ocean temperatures. These findings can help climatologists predict future climate, particularly how such events can amplify climate change caused by human activities.
This study was published in the journal Proceedings of the National Academy of Sciences (PNAS).
GotScience.org translates complex research findings into accessible insights on science, nature, and technology. Help keep GotScience free: Donate or visit our gift shop. For more science news subscribe to our weekly digest. | 0.819144 | 3.929721 |
VLA reveals 'bashful' black hole in neighboring galaxy
Thanks to the extraordinary sensitivity of the Karl G. Jansky Very Large Array (VLA), astronomers have detected what they believe is the long-sought radio emission coming from a supermassive black hole at the center of one of our closest neighboring galaxies. Evidence for the black hole's existence previously came only from studies of stellar motions in the galaxy and from X-ray observations.
The galaxy, called Messier 32 (M32), is a satellite of the Andromeda Galaxy, our own Milky Way's giant neighbor. Unlike the Milky Way and Andromeda, which are star-forming spiral galaxies, M32 is an elliptical galaxy, with little star formation. About 2.5 million light-years from Earth, M32 is much smaller than either the Milky Way or Andromeda.
Supermassive black holes are found at the cores of most galaxies, and as those black holes draw in matter from their surroundings, jets of material propelled to speeds close to that of light by the black holes often generate radio waves detectable with radio telescopes. The intensity of this radio emission depends on how voraciously the black hole is consuming surrounding matter. The central black holes of the Milky Way and Andromeda are quite weak radio emitters compared to many other galaxies.
"The very faint radio emission we think is coming from M32's central black hole indicates that this object's activity is among the weakest yet found, along with the Milky Way and Andromeda," said Yang Yang, of Nanjing University in China. "Studying such quiescent black holes gives us an excellent opportunity to advance our presently-poor understanding of their physics," she added.
The discovery was made possible by the dramatic improvement in sensitivity, or the ability to detect extremely faint radio waves, produced by a decade-long, $98 million upgrade of the VLA's electronic systems that was completed in 2012. The new VLA observations were able to detect radio emission roughly 90 times fainter than previous studies of M32.
The VLA image showed a faint radio-emitting object at the location where X-rays are being emitted and around which stars near the galaxy's center appear to be orbiting. "This tells us that the radio emission most likely is coming from the black hole, but we want to do further observations to confirm this," Yang said.
M32's black hole contains about 2.5 million times the mass of the Sun, compared to the Milky Way black hole's 4 million.
The VLA also revealed three radio-emitting objects that, the scientists said, are planetary nebulae previously seen with visible-light telescopes. Planetary nebulae are spheres of gas blown off during late stages in the lives of stars like our Sun. The M32 VLA image represents the first detection by a radio telescope of such objects at the far edges of our Local Group of galaxies.
Yang led a research team of astronomers from China and the U.S. Lorant Sjouwerman of the National Radio Astronomy Observatory was instrumental in obtaining and reducing the VLA data for the study. The scientists are reporting their findings in the Astrophysical Journal Letters. | 0.853429 | 3.973556 |
In just three years, the cloud of dust surrounding a young star has disappeared, indicating that there’s something wrong with our current ideas of planet formation.
It may mean that planets can form much more quickly than previously thought or, alternatively, that stars harboring planets could be far more numerous.
“The most commonly accepted time scale for the removal of this much dust is in the hundreds of thousands of years, sometimes millions,” says Inseok Song, assistant professor of physics and astronomy at the University of Georgia.
“What we saw was far more rapid, and has never been observed or even predicted. It tells us that we have a lot more to learn about planet formation.”
The scientists examined data from the Infrared Astronomical Satellite, or IRAS, which surveyed more than 96 percent of the sky in 1983. The star, known as TYC 8241 2652 1, is located in the Scorpius-Centaurus stellar nursery, and was originally surrounded by a cloud of dust that was identifiable by its distinctive radiation of infrared energy.
Examination in 2008 using a mid-infrared imager at the Gemini South Observatory in Chile showed the same pattern. But when observations were repeated a year later, the team discovered that infrared emission had dropped by nearly two-thirds.
And when NASA’s Wide-field Infrared Survey Explorer, or WISE, took a look in 2010, the dust had mostly disappeared.
“It’s as if you took a conventional picture of the planet Saturn today and then came back two years later and found that its rings had disappeared,” says Ben Zuckerman of UC Los Angeles.
The researchers have several different explanations – but not one fits with conventional thinking about planet formation.
One possibility is that the process of accretion, whereby minute particles of dust left over after a star forms clump onto each other, happens more quickly than thought. If so, though, it’s a lot more quickly, given that models show the process taking hundreds of thoudsands of years, rather than just, er, three.
“If what we observed is related to runaway growth, then our finding suggests that planet formation is very fast and very efficient,” says Song. “The implication is that if the conditions are right around a star, planet formation can be nearly instantaneous from an astronomical perspective.”
Unfortunately, it’s not yet possible to check, as the planet’s distance – 450 light years – means it’s too far away for a planet to be observed.
Alternatively, the star may have absorbed the dust itself, implying that planet formation is much less likely than previously thought; or the dust may have been expelled from the sun’s orbit altogether.
The fact that such clouds of dust can be so very temporary implies that there may be many more planets out there than believed.
“People often calculate the percentage of stars that have a large amount of dust to get a reasonable estimate of the percentage of stars with planetary systems, but if the dust avalanche model is correct, we cannot do that anymore,” says Song. “Many stars without any detectable dust may have mature planetary systems that are simply undetectable.” | 0.892668 | 4.012035 |
Voyager grand tour mission of the solar system
• March 25, 2020: Eight and a half years into its grand tour of the solar system, NASA's Voyager 2 spacecraft was ready for another encounter. It was January 24, 1986, and soon it would meet the mysterious seventh planet, icy-cold Uranus. 1)
- Over the next few hours, Voyager 2 flew within 50,600 miles (81,433 km) of Uranus' cloud tops, collecting data that revealed two new rings, 11 new moons and temperatures below minus 353º Fahrenheit (minus 214º Celsius). The dataset is still the only up-close measurements we have ever made of the planet.
- Three decades later, scientists reinspecting that data found one more secret.
- Unbeknownst to the entire space physics community, 34 years ago Voyager 2 flew through a plasmoid, a giant magnetic bubble that may have been whisking Uranus' atmosphere out to space. The finding, reported in Geophysical Research Letters, raises new questions about the planet's one-of-a-kind magnetic environment. 2)
A Wobbly Magnetic Oddball
- Planetary atmospheres all over the solar system are leaking into space. Hydrogen springs from Venus to join the solar wind, the continuous stream of particles escaping the Sun. Jupiter and Saturn eject globs of their electrically-charged air. Even Earth's atmosphere leaks. (Don't worry, it will stick around for another billion years or so.)
- The effects are tiny on human timescales, but given long enough, atmospheric escape can fundamentally alter a planet's fate. For a case in point, look at Mars.
- "Mars used to be a wet planet with a thick atmosphere," said Gina DiBraccio, space physicist at NASA's Goddard Space Flight Center and project scientist for the MAVEN (Mars Atmosphere and Volatile Evolution) mission. "It evolved over time" - 4 billion years of leakage to space - "to become the dry planet we see today."
- Atmospheric escape is driven by a planet's magnetic field, which can both help and hinder the process. Scientists believe magnetic fields can protect a planet, fending off the atmosphere-stripping blasts of the solar wind. But they can also create opportunities for escape, like the giant globs cut loose from Saturn and Jupiter when magnetic field lines become tangled. Either way, to understand how atmospheres change, scientists pay close attention to magnetism.
- That's one more reason Uranus is such a mystery. Voyager 2's 1986 flyby revealed just how magnetically weird the planet is.
"The structure, the way that it moves ... ," DiBraccio said, "Uranus is really on its own."
- Unlike any other planet in our solar system, Uranus spins almost perfectly on its side - like a pig on a spit roast - completing a barrel roll once every 17 hours. Its magnetic field axis points 60 degrees away from that spin axis, so as the planet spins, its magnetosphere - the space carved out by its magnetic field - wobbles like a poorly thrown football. Scientists still don't know how to model it.
- This oddity drew DiBraccio and her coauthor Dan Gershman, a fellow Goddard space physicist, to the project. Both were part of a team working out plans for a new mission to the "ice giants" Uranus and Neptune, and they were looking for mysteries to solve.
- Uranus' strange magnetic field, last measured more than 30 years ago, seemed like a good place to start.
- So they downloaded Voyager 2's magnetometer readings, which monitored the strength and direction of the magnetic fields near Uranus as the spacecraft flew by. With no idea what they'd find, they zoomed in closer than previous studies, plotting a new datapoint every 1.92 seconds. Smooth lines gave way to jagged spikes and dips. And that's when they saw it: a tiny zigzag with a big story.
- "Do you think that could be ... a plasmoid?" Gershman asked DiBraccio, catching sight of the squiggle.
- Little known at the time of Voyager 2's flyby, plasmoids have since become recognized as an important way planets lose mass. These giant bubbles of plasma, or electrified gas, pinch off from the end of a planet's magnetotail - the part of its magnetic field blown back by the Sun like a windsock. With enough time, escaping plasmoids can drain the ions from a planet's atmosphere, fundamentally changing its composition.
- They had been observed at Earth and other planets, but no one had detected plasmoids at Uranus - yet.
- DiBraccio ran the data through her processing pipeline, and the results came back clean. "I think it definitely is," she said.
The Bubble Escapes
- The plasmoid DiBraccio and Gershman found occupied a mere 60 seconds of Voyager 2's 45-hour-long flight by Uranus. It appeared as a quick up-down blip in the magnetometer data. "But if you plotted it in 3D, it would look like a cylinder," Gershman said.
Figure 1: Voyager 2 took this image as it approached the planet Uranus on 14 January 1986. The planet's hazy bluish color is due to the methane in its atmosphere, which absorbs red wavelengths of light (image credit: NASA/JPL-Caltech)
- Comparing their results to plasmoids observed at Jupiter, Saturn and Mercury, they estimated a cylindrical shape at least 127,000 miles (204,000 km) long, and up to roughly 250,000 miles (400,000 km) across. Like all planetary plasmoids, it was full of charged particles - mostly ionized hydrogen, the authors believe.?
- Readings from inside the plasmoid - as Voyager 2 flew through it - hinted at its origins. Whereas some plasmoids have a twisted internal magnetic field, DiBraccio and Gershman observed smooth, closed magnetic loops. Such loop-like plasmoids are typically formed as a spinning planet flings bits of its atmosphere to space. "Centrifugal forces take over, and the plasmoid pinches off," Gershman said. According to their estimates, plasmoids like that one could account for between 15% and 55% of atmospheric mass loss at Uranus, a greater proportion than either Jupiter or Saturn. It may well be the dominant way Uranus sheds its atmosphere to space.
- How has plasmoid escape changed Uranus over time? With only one set of observations, it's hard to say.
- "Imagine if one spacecraft just flew through this room and tried to characterize the entire Earth," DiBraccio said. "Obviously it's not going to show you anything about what the Sahara or Antarctica is like."
- But the findings help focus new questions about the planet. The remaining mystery is part of the draw. "It's why I love planetary science," DiBraccio said. "You're always going somewhere you don't really know."
- The twin Voyager spacecraft were built by and continue to be operated by NASA's Jet Propulsion Laboratory. JPL is a division of Caltech in Pasadena. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate in Washington.
• February 12, 2020: Thirty years ago on Feb. 14, 1990, NASA’s Voyager 1 spacecraft sent home a very special Valentine: A mosaic of 60 images that was intended as what the Voyager team called the first “Family Portrait” of our solar system. 3)
The spacecraft was out beyond Neptune when mission managers commanded it to look back for a final time and snap images of the worlds it was leaving behind on its journey into interstellar space.
It captured Neptune, Uranus, Saturn, Jupiter, Earth and Venus. A few key members didn’t make the shot: Mars was obscured by scattered sunlight bouncing around in the camera, Mercury was too close to the Sun and dwarf planet Pluto was too tiny, too far away and too dark to be detected. But the images gave humans an awe-inspiring and unprecedented view of their home world and its neighbors.
One of those images, the picture of Earth, would become known as the “Pale Blue Dot.” The unique view of Earth as a tiny speck in the cosmos inspired the title of scientist Carl Sagan's book, "Pale Blue Dot: A Vision of the Human Future in Space,"
But the image almost didn’t happen.
Here are 10 things you might not know about Voyager 1’s famous Pale Blue Dot photo.
1) Not in the Plan
Neither the “Family Portrait” nor the “Pale Blue Dot” photo was planned as part of the original Voyager mission. In fact, the Voyager team turned down several requests to take the images because of limited engineering resources and potential danger to the cameras from pointing them close to the Sun. It took eight years and six requests to get approval for the images.
2) A Unique Perspective
Voyager 1 remains the first and only spacecraft that has attempted to photograph our solar system. Only three spacecraft have been capable of making such an observation: Voyager 1, Voyager 2 and New Horizons. (Pioneer 10 and Pioneer 11 — the other two spacecraft headed into interstellar space — had similar vantage points, but technical challenges prevented them from getting such a shot.)
Figure 2: This data visualization uses actual spacecraft trajectory data to show the family portrait image from Voyager 1's perspective in February 1990 (image credit: NASA/JPL-Caltech)
3) A Mote of Dust
The Voyager imaging team wanted show Earth’s vulnerability — to illustrate how fragile and irreplaceable it is — and demonstrate what a small place it occupies in the universe. Earth in the image is only about a single a pixel, a pale blue dot.
4) A Happy Coincidence
The image contains scattered light that resembles beams of sunlight, making the tiny Earth appear even more dramatic. In fact, these sunbeams are camera artifacts that resulted from the necessity of pointing the camera within a few degrees of the Sun.
Voyager 1 was 40 astronomical units from the Sun at the time so Earth appeared very near our brilliant star from Voyager's vantage point. One astronomical unit is 93 million miles, or 150 million kilometers That one of the rays of light happened to intersect with Earth was a happy coincidence.
5) Carl Sagan's Dream Shot
The prominent planetary scientist Carl Sagan (1934-1996) — a member of the Voyager imaging team — had the original idea to use Voyager’s cameras to image Earth in 1981, following the mission's encounters with Saturn. Sagan later wrote in poetic detail about the image and its meaning in his book, "Pale Blue Dot: A Vision of the Human Future in Space." — "Look again at that dot." Sagan wrote. "That's here. That's home. That's us.”
Figure 3: The Pale Blue Dot is a photograph of Earth taken Feb. 14, 1990, by NASA’s Voyager 1 at a distance of 3.7 billion miles (6 billion kilometers) from the Sun. The image inspired the title of scientist Carl Sagan's book, "Pale Blue Dot: A Vision of the Human Future in Space," in which he wrote: "Look again at that dot. That's here. That's home. That's us." (image credit: NASA/JPL-Caltech)
6) Cold Cameras
Voyager 1 powered up its cameras for the images on Feb. 13 and it took three hours for them to warm up. The spacecraft’s onboard tape recorder saved all the images taken, for later playback to Earth.
7) Light Time
The images of Earth snapped by Voyager 1 captured light that had left our planet five hours and 36 minutes earlier. (This was, of course, reflected sunlight that had left the Sun eight minutes before that.)
Voyager 1 was so far from Earth it took several communications passes with NASA's Deep Space Network, over a couple of months, to transmit all the data. The last of the image data were finally downloaded on Earth on May 1, 1990.
9) Another Unique Perspective
Voyager 1 also took the first image of the entire Earth and Moon together near the start of its mission on Sept. 18, 1977. The images were taken 13 days after launch at a distance of about 7.3 million miles (11.66 million kilometers) from Earth.
10) Parting Shot
After taking the images for “The Family Portrait” at 05:22 GMT on Feb. 14, 1990, Voyager 1 powered down its cameras forever. As of early 2020 the spacecraft is still operating, but no longer has the capability to take images.
• November 4, 2019: One year ago, on Nov. 5, 2018, NASA's Voyager 2 became only the second spacecraft in history to leave the heliosphere - the protective bubble of particles and magnetic fields created by our Sun. At a distance of about 11 billion miles (18 billion kilometers) from Earth - well beyond the orbit of Pluto - Voyager 2 had entered interstellar space, or the region between stars. Today, five new research papers in the journal Nature Astronomy describe what scientists observed during and since Voyager 2's historic crossing. 4)
- Each paper details the findings from one of Voyager 2's five operating science instruments: a magnetic field sensor, two instruments to detect energetic particles in different energy ranges and two instruments for studying plasma (a gas composed of charged particles). Taken together, the findings help paint a picture of this cosmic shoreline, where the environment created by our Sun ends and the vast ocean of interstellar space begins.
- The Sun's heliosphere is like a ship sailing through interstellar space. Both the heliosphere and interstellar space are filled with plasma, a gas that has had some of its atoms stripped of their electrons. The plasma inside the heliosphere is hot and sparse, while the plasma in interstellar space is colder and denser. The space between stars also contains cosmic rays, or particles accelerated by exploding stars. Voyager 1 discovered that the heliosphere protects Earth and the other planets from more than 70% of that radiation.
- When Voyager 2 exited the heliosphere last year, scientists announced that its two energetic particle detectors noticed dramatic changes: The rate of heliospheric particles detected by the instruments plummeted, while the rate of cosmic rays (which typically have higher energies than the heliospheric particles) increased dramatically and remained high. The changes confirmed that the probe had entered a new region of space.
- Before Voyager 1 reached the edge of the heliosphere in 2012, scientists didn't know exactly how far this boundary was from the Sun. The two probes exited the heliosphere at different locations and also at different times in the constantly repeating, approximately 11-year solar cycle, over the course of which the Sun goes through a period of high and low activity. Scientists expected that the edge of the heliosphere, called the heliopause, can move as the Sun's activity changes, sort of like a lung expanding and contracting with breath. This was consistent with the fact that the two probes encountered the heliopause at different distances from the Sun.
- The new papers now confirm that Voyager 2 is not yet in undisturbed interstellar space: Like its twin, Voyager 1, Voyager 2 appears to be in a perturbed transitional region just beyond the heliosphere.
- "The Voyager probes are showing us how our Sun interacts with the stuff that fills most of the space between stars in the Milky Way galaxy," said Ed Stone, project scientist for Voyager and a professor of physics at Caltech. "Without this new data from Voyager 2, we wouldn't know if what we were seeing with Voyager 1 was characteristic of the entire heliosphere or specific just to the location and time when it crossed."
Pushing Through Plasma
- The two Voyager spacecraft have now confirmed that the plasma in local interstellar space is significantly denser than the plasma inside the heliosphere, as scientists expected. Voyager 2 has now also measured the temperature of the plasma in nearby interstellar space and confirmed it is colder than the plasma inside the heliosphere.
- In 2012, Voyager 1 observed a slightly higher-than-expected plasma density just outside the heliosphere, indicating that the plasma is being somewhat compressed. Voyager 2 observed that the plasma outside the heliosphere is slightly warmer than expected, which could also indicate it is being compressed. (The plasma outside is still colder than the plasma inside.) Voyager 2 also observed a slight increase in plasma density just before it exited the heliosphere, indicating that the plasma is compressed around the inside edge of the bubble. But scientists don't yet fully understand what is causing the compression on either side.
- If the heliosphere is like a ship sailing through interstellar space, it appears the hull is somewhat leaky. One of Voyager's particle instruments showed that a trickle of particles from inside the heliosphere is slipping through the boundary and into interstellar space. Voyager 1 exited close to the very "front" of the heliosphere, relative to the bubble's movement through space. Voyager 2, on the other hand, is located closer to the flank, and this region appears to be more porous than the region where Voyager 1 is located.
Magnetic Field Mystery
- An observation by Voyager 2's magnetic field instrument confirms a surprising result from Voyager 1: The magnetic field in the region just beyond the heliopause is parallel to the magnetic field inside the heliosphere. With Voyager 1, scientists had only one sample of these magnetic fields and couldn't say for sure whether the apparent alignment was characteristic of the entire exterior region or just a coincidence. Voyager 2's magnetometer observations confirm the Voyager 1 finding and indicate that the two fields align, according to Stone.
- The Voyager probes launched in 1978, and both flew by Jupiter and Saturn. Voyager 2 changed course at Saturn in order to fly by Uranus and Neptune, performing the only close flybys of those planets in history. The Voyager probes completed their Grand Tour of the planets and began their Interstellar Mission to reach the heliopause in 1989. Voyager 1, the faster of the two probes, is currently over 13.6 billion miles (22 billion kilometers) from the Sun, while Voyager 2 is 11.3 billion miles (18.2 billion kilometers) from the Sun. It takes light about 16.5 hours to travel from Voyager 2 to Earth. By comparison, light traveling from the Sun takes about eight minutes to reach Earth.
• October 8, 2019: Out at the boundary of our solar system, pressure runs high. This pressure, the force plasma, magnetic fields and particles like ions, cosmic rays and electrons exert on one another when they flow and collide, was recently measured by scientists in totality for the first time — and it was found to be greater than expected. 5)
- Using observations of galactic cosmic rays — a type of highly energetic particle — from NASA’s Voyager spacecraft scientists calculated the total pressure from particles in the outer region of the solar system, known as the heliosheath. At nearly 9 billion miles away, this region is hard to study. But the unique positioning of the Voyager spacecraft and the opportune timing of a solar event made measurements of the heliosheath possible. And the results are helping scientists understand how the Sun interacts with its surroundings.
- “In adding up the pieces known from previous studies, we found our new value is still larger than what’s been measured so far,” said Jamie Rankin, lead author on the new study and astronomer at Princeton University in New Jersey. “It says that there are some other parts to the pressure that aren’t being considered right now that could contribute.”
Figure 4: An illustration depicting the layers of the heliosphere (image credit: NASA/IBEX/Adler Planetarium)
- On Earth we have air pressure, created by air molecules drawn down by gravity. In space there’s also a pressure created by particles like ions and electrons. These particles, heated and accelerated by the Sun create a giant balloon known as the heliosphere extending millions of miles out past Pluto. The edge of this region, where the Sun’s influence is overcome by the pressures of particles from other stars and interstellar space, is where the Sun’s magnetic influence ends. (Its gravitational influence extends much farther, so the solar system itself extends farther, as well.)
- In order to measure the pressure in the heliosheath, the scientists used the Voyager spacecraft, which have been travelling steadily out of the solar system since 1977. At the time of the observations, Voyager 1 was already outside of the heliosphere in interstellar space, while Voyager 2 still remained in the heliosheath.
- “There was really unique timing for this event because we saw it right after Voyager 1 crossed into the local interstellar space,” Rankin said. “And while this is the first event that Voyager saw, there are more in the data that we can continue to look at to see how things in the heliosheath and interstellar space are changing over time.”
Figure 5: The Voyager spacecraft, one in the heliosheath and the other just beyond in interstellar space, took measurements as a solar even known as a global merged interaction region passed by each spacecraft four months apart. These measurements allowed scientists to calculate the total pressure in the heliosheath, as well as the speed of sound in the region (image credit: NASA's Goddard Space Flight Center/Mary Pat Hrybyk-Keith)
- The scientists used an event known as a global merged interaction region, which is caused by activity on the Sun. The Sun periodically flares up and releases enormous bursts of particles, like in coronal mass ejections. As a series of these events travel out into space, they can merge into a giant front, creating a wave of plasma pushed by magnetic fields.
- When one such wave reached the heliosheath in 2012, it was spotted by Voyager 2. The wave caused the number of galactic cosmic rays to temporarily decrease. Four months later, the scientists saw a similar decrease in observations from Voyager 1, just across the solar system’s boundary in interstellar space.
- Knowing the distance between the spacecraft allowed them to calculate the pressure in the heliosheath as well as the speed of sound. In the heliosheath sound travels at around 300 km/second — a thousand times faster than it moves through air.
- The scientists noted that the change in galactic cosmic rays wasn’t exactly identical at both spacecraft. At Voyager 2 inside the heliosheath, the number of cosmic rays decreased in all directions around the spacecraft. But at Voyager 1, outside the solar system, only the galactic cosmic rays that were traveling perpendicular to the magnetic field in the region decreased. This asymmetry suggests that something happens as the wave transmits across the solar system’s boundary.
- “Trying to understand why the change in the cosmic rays is different inside and outside of the heliosheath remains an open question,” Rankin said.
- Studying the pressure and sound speeds in this region at the boundary of the solar system can help scientists understand how the Sun influences interstellar space. This not only informs us about our own solar system, but also about the dynamics around other stars and planetary systems.
• July 8, 2019: With careful planning and dashes of creativity, engineers have been able to keep NASA's Voyager 1 and 2 spacecraft flying for nearly 42 years - longer than any other spacecraft in history. To ensure that these vintage robots continue to return the best science data possible from the frontiers of space, mission engineers are implementing a new plan to manage them. And that involves making difficult choices, particularly about instruments and thrusters. 6)
- One key issue is that both Voyagers, launched in 1977, have less and less power available over time to run their science instruments and the heaters that keep them warm in the coldness of deep space. Engineers have had to decide what parts get power and what parts have to be turned off on both spacecraft. But those decisions must be made sooner for Voyager 2 than Voyager 1 because Voyager 2 has one more science instrument collecting data - and drawing power - than its sibling.
Figure 6: This artist's concept depicts one of NASA's Voyager spacecraft, including the location of the CRS (Cosmic Ray Subsystem) instrument. Both Voyagers launched with operating CRS instruments (image credit: NASA/JPL-Caltech)
- After extensive discussions with the science team, mission managers recently turned off a heater for the cosmic ray subsystem instrument (CRS) on Voyager 2 as part of the new power management plan. The cosmic ray instrument played a crucial role last November in determining that Voyager 2 had exited the heliosphere, the protective bubble created by a constant outflow (or wind) of ionized particles from the Sun. Ever since, the two Voyagers have been sending back details of how our heliosphere interacts with the wind flowing in interstellar space, the space between stars.
- Not only are Voyager mission findings providing humanity with observations of truly uncharted territory, but they help us understand the very nature of energy and radiation in space - key information for protecting NASA's missions and astronauts even when closer to home.
- Mission team members can now preliminarily confirm that Voyager 2's cosmic ray instrument is still returning data, despite dropping to a chilly minus 74 degrees Fahrenheit (minus 59 degrees Celsius). This is lower than the temperatures at which CRS was tested more than 42 years ago (down to minus 49 degrees Fahrenheit, or minus 45 degrees Celsius). Another Voyager instrument also continued to function for years after it dropped below temperatures at which it was tested.
- ”It's incredible that Voyagers' instruments have proved so hardy," said Voyager Project Manager Suzanne Dodd, who is based at NASA's Jet Propulsion Laboratory in Pasadena, California. "We're proud they've withstood the test of time. The long lifetimes of the spacecraft mean we're dealing with scenarios we never thought we'd encounter. We will continue to explore every option we have in order to keep the Voyagers doing the best science possible."
- Voyager 2 continues to return data from five instruments as it travels through interstellar space. In addition to the cosmic ray instrument, which detects fast-moving particles that can originate from the Sun or from sources outside our solar system, the spacecraft is operating two instruments dedicated to studying plasma (a gas in which atoms have been ionized and electrons float freely) and a magnetometer (which measures magnetic fields) for understanding the sparse clouds of material in interstellar space.
- Taking data from a range of directions, the low-energy charged particle instrument is particularly useful for studying the probe's transition away from our heliosphere. Because CRS can look only in certain fixed directions, the Voyager science team decided to turn off CRS's heater first.
- Voyager 1, which crossed into interstellar space in August 2012, continues to collect data from its cosmic ray instrument as well, plus from one plasma instrument, the magnetometer and the low-energy charged particle instrument.
Why Turn Off Heaters?
- Launched separately in 1977, the two Voyagers are now over 11 billion miles (18 billion kilometers) from the Sun and far from its warmth. Engineers have to carefully control temperature on both spacecraft to keep them operating. For instance, if fuel lines powering the thrusters that keep the spacecraft oriented were to freeze, the Voyagers' antennae could stop pointing at Earth. That would prevent engineers from sending commands to the spacecraft or receiving scientific data. So the spacecraft were designed to heat themselves.
- But running heaters - and instruments - requires power, which is constantly diminishing on both Voyagers.
- Each of the probes is powered by three RTGs (Radioisotope Thermoelectric Generators), which produce heat via the natural decay of plutonium-238 radioisotopes and convert that heat into electrical power. Because the heat energy of the plutonium in the RTGs declines and their internal efficiency decreases over time, each spacecraft is producing about 4 fewer watts of electrical power each year. That means the generators produce about 40% less than what they did at launch nearly 42 years ago, limiting the number of systems that can run on the spacecraft.
- The mission's new power management plan explores multiple options for dealing with the diminishing power supply on both spacecraft, including shutting off additional instrument heaters over the next few years.
Revving Up Old Jet Packs
- Another challenge that engineers have faced is managing the degradation of some of the spacecraft thrusters, which fire in tiny pulses, or puffs, to subtly rotate the spacecraft. This became an issue in 2017, when mission controllers noticed that a set of thrusters on Voyager 1 needed to give off more puffs to keep the spacecraft's antenna pointed at Earth. To make sure the spacecraft could continue to maintain proper orientation, the team fired up another set of thrusters on Voyager 1 that hadn't been used in 37 years.
- Voyager 2's current thrusters have started to degrade, too. Mission managers have decided to make the same thruster switch on that probe this month. Voyager 2 last used these thrusters (known as trajectory correction maneuver thrusters) during its encounter with Neptune in 1989.
Many Miles to Go Before They Sleep
- The engineers' plan to manage power and aging parts should ensure that Voyager 1 and 2 can continue to collect data from interstellar space for several years to come. Data from the Voyagers continue to provide scientists with never-before-seen observations of our boundary with interstellar space, complementing NASA's IBEX (Interstellar Boundary Explorer), a mission that is remotely sensing that boundary. NASA is also preparing IMAP (Interstellar Mapping and Acceleration Probe), due to launch in 2024,to capitalize on the Voyagers' observations.
- "Both Voyager probes are exploring regions never before visited, so every day is a day of discovery," said Voyager Project Scientist Ed Stone, who is based at Caltech. "Voyager is going to keep surprising us with new insights about deep space."
- The Voyager spacecraft were built by JPL, which continues to operate both. JPL is a division of Caltech in Pasadena. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate in Washington.
• May 22, 2019: Former Jet Propulsion Laboratory Director Edward Stone - currently the David Morrisroe Professor of Physics at Caltech and the project scientist for NASA's Voyager mission for the past 47 years - has been awarded the prestigious Shaw Prize in Astronomy "for his leadership in the Voyager project, which has, over the past four decades, transformed our understanding of the four giant planets and the outer solar system, and has now begun to explore interstellar space," according to the award citation. The prize comes with a monetary award of $1.2 million. 7)
Figure 7: Ed Stone stands before a full-size model of Voyager at JPL (image credit: NASA/JPL-Caltech)
- "This is a tremendous honor," said Stone, "and a tribute to the teams who designed, developed, launched and operated Voyager on an inspiring journey of more than four decades."
- Since 1972, Stone has served as the project scientist for the Voyager mission, twin spacecraft designed to tour the solar system and its farthest reaches. The Voyager mission is managed by JPL in Pasadena, California, which Caltech manages for NASA.
- Voyager 2 launched in August 1977, and Voyager 1 soon followed, launching in September 1977. Some of the mission's many highlights include the first high-resolution images of the four giant planets of our solar system (Jupiter, Saturn, Uranus and Neptune); the discovery of volcanoes on Jupiter's moon Io; the first images of rings of Jupiter, Uranus, and Neptune; and the discovery of gaps and other complex structures in Saturn's rings.
- In 2012, Voyager 1 became the first human-made object to cross into interstellar space, beyond the protective bubble, or heliosphere, that surrounds our solar system. Voyager 2 achieved this milestone more recently, in 2018. Both missions carry Golden Records of Earth sounds, music, images and messages.
- Stone was born in Knoxville, Iowa, on January 23, 1936. He graduated from Iowa's Burlington Junior College in 1956 and earned his Ph.D. in physics from the University of Chicago in 1964. Since the Voyager spacecraft launched in 1977, Stone has led and coordinated 11 instrument teams on the project. He also served as the director of JPL from 1991 to 2001, overseeing many space-based missions, including Cassini, and a program of Mars exploration that included Mars Pathfinder and its Sojourner rover.
- Stone also played a key role in the development of the W. M. Keck Observatory in Hawaii. In the mid 1980s through the 1990s, he served as a vice chairman and chairman of the board of directors of the California Association for Research in Astronomy, which is responsible for building and operating Keck. He is also on the board of the W. M. Keck Foundation. He is currently playing a similar role in the development of the planned Thirty Meter Telescope, an international partnership that includes the U.S., Canada, China, Japan and India.
- Stone came to Caltech in 1964 as a research fellow, joining the faculty as an assistant professor in 1967. He became the Morrisroe professor in 1994 and, in 2004, became the vice provost for special projects at Caltech.
- He has served as a principal investigator on nine missions and as a co-investigator on five additional missions. He has more than 1,000 publications in professional journals and conference proceedings, and has mentored a large number of students, postdocs, and research scientists. Stone is the recipient of numerous awards, including the President's National Medal of Science (1991), the Magellanic Premium (1992), the Carl Sagan Memorial Award (1999), the Philip J. Klass Award for Lifetime Achievement (2007), the NASA Distinguished Public Service Medal (2013) and the Howard Hughes Memorial Award (2014). He is a member of the National Academy of Sciences.
- The Shaw Prize is awarded annually in three categories: Astronomy, Life Science and Medicine, and Mathematical Sciences. It is an international award managed and administered by The Shaw Prize Foundation based in Hong Kong. Mr. Shaw has also founded The Sir Run Run Shaw Charitable Trust and The Shaw Foundation Hong Kong, both dedicated to the promotion of education, scientific and technological research, medical and welfare services, and culture and the arts.
- The 2019 Shaw laureates will receive their awards in Hong Kong at the ceremonial prize-giving on Wednesday, Sept. 25, 2019.
• March 27, 2019: By all means, Voyager 1 and Voyager 2 shouldn’t even be here. Now in interstellar space, they are pushing the limits of spacecraft and exploration, journeying through the cosmic neighborhood, giving us our first direct look into the space beyond our star. 8)
But when they launched in 1977, Voyager 1 and Voyager 2 had a different mission: to explore the outer solar system and gather observations directly at the source, from outer planets we had only seen with remote studies. But now, four decades after launch, they’ve journeyed farther than any other spacecraft from Earth; into the cold, quiet world of interstellar space.
Originally designed to measure the properties of the giant planets, the instruments on both spacecraft have spent the past few decades painting a picture of the propagation of solar events from our Sun. And the Voyagers' new mission focuses not only on effects on space from within our heliosphere — the giant bubble around the Sun filled up by the constant outflow of solar particles called the solar wind — but from outside of it. Though they once helped us look closer at the planets and their relationship to the Sun, they now give us clues about the nature of interstellar space as the spacecraft continue their journey.
The environment they explore is colder, subtler and more tenuous than ever before, and yet the Voyagers continue on, exploring and measuring the interstellar medium, a smorgasbord of gas, plasma and particles from stars and gas regions not originating from our system. Three of the spacecraft's 10 instruments are the major players that study how space inside the heliosphere differs from interstellar space. Looking at this data together allows scientist to piece together our best-yet picture of the edge of the heliosphere and the interstellar medium. Here are the stories they tell.
On the Sun Spot, we have been exploring the various instruments on Voyager 2 one at a time, and analyzing how scientists read the individual sets of data sent to Earth from the far-reaching spacecraft. But one instrument we have not yet talked about is Voyager 2’s Magnetometer, or MAG for short.
During the Voyagers' first planetary mission, the MAG was designed to investigate the magnetospheres of planets and their moons, determining the physical mechanics and processes of the interactions of those magnetic fields and the solar wind. After that mission ended, the Voyager spacecraft studied the magnetic field of the heliosphere and beyond, observing the magnetic reach of the Sun and the changes that occur within that reach during solar activity.
Getting the magnetic data as we travel further into space requires an interesting trick. Voyager spins itself around, in a calibration maneuver that allows Voyager to differentiate between the spacecraft's own magnetic field — that goes along for the ride as it spins — and the magnetic fields of the space it’s traveling through.
Figure 8: Illustration of NASA’s Voyager spacecraft, with the Magnetometer (MAG) instrument and its boom displayed (image credit: NASA’s Goddard Space Flight Center/Jet Propulsion Laboratory/Mary Pat Hrybyk-Keith)
The initial peek into the magnetic field beyond the Sun’s influence happened when Voyager 1 crossed the heliopause in 2012. Scientists saw that within the heliosphere, the strength of the magnetic field was quite variable, changing and jumping as Voyager 1 moved through the heliosphere. These changes are due to solar activity. But once Voyager 1 crossed into interstellar space, that variability was silenced. Although the strength of the field was similar to what it was inside the heliosphere, it no longer had the variability associated with the Sun’s outbursts.
Figure 9: Magnetometer (MAG) data taken from Voyager 1 during its transition into interstellar space in 2012 (image credit: NASA’s Goddard Space Flight Center/Jet Propulsion Laboratory)
This graph shows the magnitude, or the strength, of the magnetic field around the heliopause from January 2012 out to May 2014. Before encountering the heliopause, marked by the orange line, the magnetic strength fluctuates quite a bit. After a bumpy ride through the heliopause in 2012, the magnetic strength stops fluctuating and begins to stabilize in 2013, once the spacecraft is far enough out into the interstellar medium.
The Cosmic Ray Subsystem
Much like the MAG, the CRS (Cosmic Ray Subsystem) was originally designed to measure planetary systems. The CRS focused on the compositions of energetic particles in the magnetospheres of Jupiter, Saturn, Uranus and Neptune. Scientists used it to study the charged particles within the solar system and their distribution between the planets. Since it passed the planets, however, the CRS has been studying the heliosphere’s charged particles and — now — the particles in the interstellar medium.
The CRS measures the count rate, or how many particles detected per second. It does this by using two telescopes: the High Energy Telescope, which measures high energy particles (70MeV) identifiable as interstellar particles, and the Low Energy Telescope, which measures low-energy particles (5MeV) that originate from our Sun. You can think of these particles like a bowling ball hitting a bowling pin versus a bullet hitting the same pin — both will make a measurable impact on the detector, but they're moving at vastly different speeds. By measuring the amounts of the two kinds of particles, Voyager can provide a sense of the space environment it’s traveling through.
Figure 10: Illustration of NASA’s Voyager spacecraft, with the Cosmic Ray Subsystem (CRS) highlighted (image credit: NASA’s Goddard Space Flight Center/Jet Propulsion Laboratory/Mary Pat Hrybyk-Keith)
Figure 11: Scientists compared data from Voyager 1 with its 2012 crossing of the heliopause to watch for clue for when Voyager 2 would cross. In November 2018, the first clues came from the Cosmic Ray Subsystem! (image credit: NASA’s Jet Propulsion Laboratory/NASA Headquarters/Patrick Koehn)
These graphs show the count rate — how many particles per second are interacting with the CRS on average each day — of the galactic ray particles measured by the High Energy Telescope (top graph) and the heliospheric particles measured by the Low Energy Telescope (bottom graph). The line in red shows the data from Voyager 1, time shifted forward 6.32 years from 2012 to match up with the data from Voyager around November 2018, shown in blue.
CRS data from Voyager 2 on Nov. 5, 2018, showed the interstellar particle count rate of the High Energy Telescope increasing to count rates similar to what Voyager 1 saw then leveling out. Similarly, the Low Energy Telescope shows a severe decrease in heliospheric originating particles. This was a key indication that Voyager 2 had moved into interstellar space. Scientists can keep watching these counts to see if the composition of interstellar space particles changes along the journey.
The Plasma Instrument
The PLS (Plasma Science) instrument was made to measure plasma and ionized particles around the outer planets and to measure the solar wind’s influence on those planets. The PLS is made up of four Faraday cups, an instrument that measures the plasma as it passes through the cups and calculates the plasma’s speed, direction and density.
The plasma instrument on Voyager 1 was damaged during a fly-by of Saturn and had to be shut off long before Voyager 1 exited the heliosphere, making it unable to measure the interstellar medium’s plasma properties. With Voyager 2's crossing, scientists will get the first-ever plasma measurements of the interstellar medium.
Figure 12: Illustration of NASA’s Voyager spacecraft, with the PLS (Plasma Science) instrument displayed (image credit: NASA’s Goddard Space Flight Center/Jet Propulsion Laboratory/Mary Pat Hrybyk-Keith)
Scientists predicted that interstellar plasma measured by Voyager 2 would be higher in density but lower in temperature and speed than plasma inside the heliosphere. And in November 2018, the instrument saw just that for the first time. This suggests that the plasma in this region is getting colder and slower, and, like cars slowing down on a freeway, is beginning to pile up around the heliopause and into the interstellar medium.
And now, thanks to Voyager 2’s PLS, we have a never-before-seen perspective on our heliosphere: The plasma velocity from Earth to the heliopause.
Figure 13: With Voyager 2 crossing the heliopause, scientists now have a new view of solar wind plasma across the heliosphere (image credit: NASA's Jet Propulsion Laboratory/ Michigan Institute of Technology/John Richardson)
These three graphs tell an amazing story, summarizing a journey of 42 years in one plot. The top section of this graph shows the plasma velocity, how fast the plasma across the heliosphere is moving, against the distance out from Earth. The distance is in astronomical units; one astronomical unit is the average distance between the Sun and Earth, about 93 million miles (150 million km). For context, Saturn is 10 AU from Earth, while Pluto is about 40 AU away.
The heliopause crossing happened at 120 AU, when the velocity of plasma coming out from the Sun drops to zero (seen on the top graph), and the outward flow of the plasma is diverted — seen in the increase in the two bottom graphs, which show the upwards and downward speeds (the normal velocity, middle graph) and the sideways speed of the solar wind (the tangential velocity, bottom graph) of the solar wind plasma, respectively. This means as the solar wind begins to interact with the interstellar medium, it is pushed out and away, like a wave hitting the side of a cliff.
Looking at each instrument in isolation, however, does not tell the full story of what interstellar space at the heliopause looks like. Together, these instruments tell a story of the transition from the turbulent, active space within our Sun's influence to the relatively calm waters on the edge of interstellar space.
The MAG shows that the magnetic field strength decreases sharply in the interstellar medium. The CRS data shows an increase in interstellar cosmic rays, and a decrease in heliospheric particles. And finally, the PLS shows that there’s no longer any detectable solar wind.
Now that the Voyagers are outside of the heliosphere, their new perspective will provide new information about the formation and state of our Sun and how it interacts with interstellar space, along with insight into how other stars interact with the interstellar medium.
Voyager 1 and Voyager 2 are providing our first look at the space we would have to pass through if humanity ever were to travel beyond our home star — a glimpse of our neighborhood in space.
• December 10, 2018: For the second time in history, a human-made object has reached the space between the stars. NASA's Voyager 2 probe now has exited the heliosphere - the protective bubble of particles and magnetic fields created by the Sun. 9)
Figure 14: This illustration shows the position of NASA's Voyager 1 and Voyager 2 probes, outside of the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto. Voyager 1 crossed the heliopause, or the edge of the heliosphere, in August 2012. Heading in a different direction, Voyager 2 crossed another part of the heliopause in November 2018 (image credit: NASA/JPL-Caltech)
Comparing data from different instruments aboard the trailblazing spacecraft, mission scientists determined the probe crossed the outer edge of the heliosphere on 5 November. This boundary, called the heliopause, is where the tenuous, hot solar wind meets the cold, dense interstellar medium. Its twin, Voyager 1, crossed this boundary in 2012, but Voyager 2 carries a working instrument that will provide first-of-its-kind observations of the nature of this gateway into interstellar space.
Figure 15: NASA’s Voyager 2 enters interstellar space (video credit: NASA/JPL-Caltech)
Voyager 2 now is slightly more than 11 billion miles (18 billion km) from Earth. Mission operators still can communicate with Voyager 2 as it enters this new phase of its journey, but information – moving at the speed of light – takes about 16.5 hours to travel from the spacecraft to Earth. By comparison, light traveling from the Sun takes about eight minutes to reach Earth.
The most compelling evidence of Voyager 2’s exit from the heliosphere came from its onboard Plasma Science Experiment (PLS), an instrument that stopped working on Voyager 1 in 1980, long before that probe crossed the heliopause. Until recently, the space surrounding Voyager 2 was filled predominantly with plasma flowing out from our Sun. This outflow, called the solar wind, creates a bubble – the heliosphere – that envelopes the planets in our solar system. The PLS uses the electrical current of the plasma to detect the speed, density, temperature, pressure and flux of the solar wind. The PLS aboard Voyager 2 observed a steep decline in the speed of the solar wind particles on 5 November. Since that date, the plasma instrument has observed no solar wind flow in the environment around Voyager 2, which makes mission scientists confident the probe has left the heliosphere.
Figure 16: At the end of 2018, the cosmic ray subsystem aboard NASA’s Voyager 2 spacecraft provided evidence that Voyager 2 had left the heliosphere. There were steep drops in the rate of heliospheric particles that hit the instrument's radiation detector. At the same time, there were significant increases in the rate at which particles that originate outside our heliosphere (also known as galactic cosmic rays) hit the detector (image credit: NASA/JPL-Caltech/GSFC)
Legend to Figure 16: The graphs show data from Voyager 2's CRS, which averages the number of particle hits over a six-hour block of time. CRS detects both lower-energy particles that originate inside the heliosphere (greater than 0.5 MeV) and higher-energy particles that originate farther out in the galaxy (greater than 70 MeV).
In addition to the plasma data, Voyager’s science team members have seen evidence from three other onboard instruments – the cosmic ray subsystem, the low energy charged particle instrument and the magnetometer – that is consistent with the conclusion that Voyager 2 has crossed the heliopause. Voyager’s team members are eager to continue to study the data from these other onboard instruments to get a clearer picture of the environment through which Voyager 2 is traveling.
Figure 17: The set of graphs on the left illustrates the drop in electrical current detected in three directions by Voyager 2's plasma science experiment (PLS) to background levels. They are among the key pieces of data that Voyager scientists used to determine that Voyager 2 entered interstellar space, the space between stars, in November 2018. The disappearance in electrical current in the sunward-looking detectors indicates the spacecraft is no longer in the outward flow of solar wind plasma. It is instead in a new plasma environment — interstellar medium plasma. The image on the right shows the Faraday cups of the PLS. The three sunward pointed cups point in slightly different directions in order to measure the direction of the solar wind. The fourth cup (on the upper left) points perpendicular to the others (image credit: NASA/JPL-Caltech)
“There is still a lot to learn about the region of interstellar space immediately beyond the heliopause,” said Ed Stone, Voyager project scientist based at Caltech in Pasadena, California.
Together, the two Voyagers provide a detailed glimpse of how our heliosphere interacts with the constant interstellar wind flowing from beyond. Their observations complement data from NASA’s Interstellar Boundary Explorer (IBEX), a mission that is remotely sensing that boundary. NASA also is preparing an additional mission – the upcoming Interstellar Mapping and Acceleration Probe (IMAP), due to launch in 2024 – to capitalize on the Voyagers’ observations.
“Voyager has a very special place for us in our heliophysics fleet,” said Nicola Fox, director of the Heliophysics Division at NASA Headquarters. “Our studies start at the Sun and extend out to everything the solar wind touches. To have the Voyagers sending back information about the edge of the Sun’s influence gives us an unprecedented glimpse of truly uncharted territory.”
While the probes have left the heliosphere, Voyager 1 and Voyager 2 have not yet left the solar system, and won’t be leaving anytime soon. The boundary of the solar system is considered to be beyond the outer edge of the Oort Cloud, a collection of small objects that are still under the influence of the Sun’s gravity. The width of the Oort Cloud is not known precisely, but it is estimated to begin at about 1,000 astronomical units (AU) from the Sun and to extend to about 100,000 AU. One AU is the distance from the Sun to Earth. It will take about 300 years for Voyager 2 to reach the inner edge of the Oort Cloud and possibly 30,000 years to fly beyond it.
Figure 18: This artist's concept puts solar system distances in perspective. The scale bar is in astronomical units, with each set distance beyond 1 AU representing 10 times the previous distance. One AU is the distance from the Sun to the Earth, which is about 150 million kilometers. Neptune, the most distant planet from the Sun, is about 30 AU (image credit: NASA/JPL-Caltech)
The Voyager probes are powered using heat from the decay of radioactive material, contained in a device called RTG (Radioisotope Thermal Generator). The power output of the RTGs diminishes by about four watts per year, which means that various parts of the Voyagers, including the cameras on both spacecraft, have been turned off over time to manage power.
“I think we’re all happy and relieved that the Voyager probes have both operated long enough to make it past this milestone,” said Suzanne Dodd, Voyager project manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “This is what we've all been waiting for. Now we’re looking forward to what we’ll be able to learn from having both probes outside the heliopause.”
Voyager 2 launched on 20 August 1977, 16 days before Voyager 1 (launch on 5 September 1977), and both have traveled well beyond their original destinations. The spacecraft were built to last five years and conduct close-up studies of Jupiter and Saturn. However, as the mission continued, additional flybys of the two outermost giant planets, Uranus and Neptune, proved possible. As the spacecraft flew across the solar system, remote-control reprogramming was used to endow the Voyagers with greater capabilities than they possessed when they left Earth. Their two-planet mission became a four-planet mission. Their five-year lifespans have stretched to 41 years, making Voyager 2 NASA’s longest running mission.
The Voyager story has impacted not only generations of current and future scientists and engineers, but also Earth's culture, including film, art and music. Each spacecraft carries a Golden Record of Earth sounds, pictures and messages. Since the spacecraft could last billions of years, these circular time capsules could one day be the only traces of human civilization.
Voyager’s mission controllers communicate with the probes using NASA’s Deep Space Network (DSN), a global system for communicating with interplanetary spacecraft. The DSN consists of three clusters of antennas in Goldstone, California; Madrid, Spain; and Canberra, Australia.
The Voyager Interstellar Mission is a part of NASA’s Heliophysics System Observatory, sponsored by the Heliophysics Division of NASA’s Science Mission Directorate in Washington. JPL built and operates the twin Voyager spacecraft. NASA’s DSN, managed by JPL, is an international network of antennas that supports interplanetary spacecraft missions and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions. The CSIRO (Commonwealth Scientific and Industrial Research Organization), Australia’s national science agency, operates both the CDSCC (Canberra Deep Space Communication Complex), part of NASA's DSN, and the Parkes Observatory of CSIRO, which NASA has been using to downlink data from Voyager 2 since 8 November.
Australia's national science agency, CSIRO, is supporting NASA’s Voyager 2 spacecraft as it enters interstellar space.
• On 8 November 2018, CSIRO's Parkes radio telescope joined NASA's CDSCC (Canberra Deep Space Communication Complex), part of NASA's Deep Space Network, to receive unique and historic data from Voyager 2. This provides a clearer picture of the environment through which Voyager 2 is travelling. The Parkes telescope will continue to receive downlink data into early 2019. 10)
- NASA has engaged the Parkes telescope to support receiving this historic data from Voyager 2 while CDSCC is busy with communications for other deep space missions that are making their own important encounters during this period, such as New Horizons' flyby of the most distant object yet to be explored by a spacecraft, coming up on New Year's Day.
- Because of Voyager 2's location and distance from Earth, CDSCC and the Parkes telescope are the only facilities in the world that are capable of having contact with the spacecraft.
- Voyager 2 isn't able to record its data on board – it transmits it directly from the instruments back to Earth – making it essential to receive as much of this vital data as possible.
- CSIRO Chief Executive Dr Larry Marshall said CSIRO was here to solve the greatest challenges with science. "So we're proud to help NASA solve the scientific challenge of capturing this once in a lifetime opportunity as Voyager 2 ventures into interstellar space," Dr Marshall said.
- "Our team at Parkes has partnered with NASA on some of humanity's most momentous steps in space, including the landing of the Mars Rover Curiosity and, almost fifty years ago, the Apollo 11 Moon landing.
- CSIRO Director of Astronomy and Space Science Dr Douglas Bock explained how the additional support from Parkes would track Voyager 2. "The Canberra Deep Space Communication Complex, which CSIRO operates on behalf of NASA, has been providing command, telemetry and control for the twin Voyager spacecraft since their launch in 1977," Dr Bock said.
- "NASA has engaged our 64 m Parkes radio telescope to 'combine forces' with CDSCC's 70 m antenna, Deep Space Station 43 (DSS43), to capture as much scientifically valuable data as possible during this critical period.
- "The Parkes telescope will be tracking Voyager 2 for 11 hours a day while the spacecraft is observable from Parkes. CDSCC's DSS43 will also track Voyager 2 for a number of hours both before and after Parkes, expanding the available observation time. - This is a highlight of CSIRO's decades' worth of experience operating large, complex spacecraft tracking and radio astronomy infrastructure."
Legend to Figure 19: The Parkes radio telescope is located outside the town of Parkes in the central-west region of New South Wales, about 380 km from Sydney. It's one of three instruments that make up the Australia Telescope National Facility. Parkes is one of the largest single-dish telescopes in the southern hemisphere dedicated to astronomy. It started operating in 1961, but only its basic structure has remained unchanged. The surface, control system, focus cabin, receivers, computers and cabling have all been upgraded – some parts many times – to keep the telescope at the cutting edge of radio astronomy. The telescope is now 10,000 times more sensitive than when it was commissioned.
Legend to Figure 20: CDSCC is part of NASA’s Deep Space Network (DSN) which connects scientists around the world with their robotic spacecraft exploring the Solar System and beyond. Since 2010, CSIRO has partnered with NASA to manage the Canberra facility on their behalf. The DSN also has two other station complexs located near Madrid, Spain and Goldstone, California.The Canberra facility is dominated by a massive 70 m dish, the largest steerable parabolic antenna in the southern hemisphere. Along with three additional 34 m dishes across the site, they transmit and receive data from over 40 missions in deep space, including both of NASA’s Voyager spacecraft.
NASA's Deep Space Antenna Upgrades to Affect Voyager Communications
Starting in early March 2020, NASA's Voyager 2 will quietly coast through interstellar space without receiving commands from Earth. That's because the Voyager's primary means of communication, the Deep Space Network's 70-meter-wide (230-feet-wide) radio antenna in Canberra, Australia, will be undergoing critical upgrades for about 11 months. During this time, the Voyager team will still be able to receive science data from Voyager 2 on its mission to explore the outermost edge of the Sun's domain and beyond. 11)
The Deep Space Network's Canberra facility in Australia is the only antenna that can send commands to the Voyager 2 spacecraft. The antenna enhancements will improve future spacecraft communications, but during the upgrades, Voyager 2 will not be able to receive new commands from Earth.
About the size of a 20-story office building, the dish has been in service for 48 years. Some parts of the 70-meter antenna, including the transmitters that send commands to various spacecraft, are 40 years old and increasingly unreliable. The Deep Space Network (DSN) upgrades are planned to start now that Voyager 2 has returned to normal operations, after accidentally overdrawing its power supply and automatically turning off its science instruments in January.
The network operates 24 hours a day, 365 days a year and is spread over three sites around the world, in California, Spain and Australia. This allows navigators to communicate with spacecraft at the Moon and beyond at all times during Earth's rotation. Voyager 2, which launched in 1977, is currently more than 11 billion miles (17 billion kilometers) from Earth. It is flying in a downward direction relative to Earth's orbital plane, where it can be seen only from the southern hemisphere and thus can communicate only with the Australian site.
Moreover, a special S-band transmitter is required to send commands to Voyager 2 - one both powerful enough to reach interstellar space and on a frequency that can communicate with Voyager's dated technology. The Canberra 70-meter antenna (called "DSS43") is the only such antenna in the southern hemisphere. As the equipment in the antenna ages, the risk of unplanned outages will increase, which adds more risk to the Voyager mission. The planned upgrades will not only reduce that risk, but will also add state-of-the art technology upgrades that will benefit future missions.
"Obviously, the 11 months of repairs puts more constraints on the other DSN sites," said Jeff Berner, Deep Space Network's chief engineer. "But the advantage is that when we come back, the Canberra antenna will be much more reliable."
The repairs will benefit far more than Voyager 2, including future missions like the Mars 2020 rover and Moon to Mars exploration efforts. The network will play a critical role in ensuring communication and navigation support for both the precursor Moon and Mars missions and the crewed Artemis missions. "The maintenance is needed to support the missions that NASA is developing and launching in the future, as well as supporting the missions that are operating right now," said Suzanne Dodd, Voyager project manager and JPL Director for the Interplanetary Network.
The three Canberra 34-meter (111-foot) antennas can be configured to listen to Voyager 2's signal; they just won't be able to transmit commands. In the meantime, said Dodd, the Voyager team will put the spacecraft into a quiescent state, which will still allow it to send back science data during the 11-month downtime.
"We put the spacecraft back into a state where it will be just fine, assuming that everything goes normally with it during the time that the antenna is down," said Dodd. "If things don't go normally - which is always a possibility, especially with an aging spacecraft - then the onboard fault protection that's there can handle the situation."
Berner says the work on the 70-meter antenna is like bringing an old car into the shop: There's never a good time to do it, but it will make the car much more dependable if you do.
The work on the Canberra DSN station is expected to be completed by January 2021. The DSN is managed by NASA's Jet Propulsion Laboratory for the agency's Human Exploration and Operations' Space Communication and Navigation program.
1) Miles Hatfield, ”Revisiting Decades-Old Voyager 2 Data, Scientists Find One More Secret,” NASA/JPL News, 25 March 2020, URL: https://www.jpl.nasa.gov/news/news.php?feature=7623
2) Gina A. DiBraccio, Daniel J. Gershman, ”Voyager 2 constraints on plasmoid‐based transport at Uranus,” Geophysical Research Letters, Volume46, Issue19, 16 October 2019, Pages 10710-10718, https://doi.org/10.1029/2019GL083909
”10 Things You Might Not Know About Voyager's Famous 'Pale Blue
Dot' Photo,” NASA Solar System Exploration, 12 February 2020,
4) ”Voyager 2 Illuminates Boundary of Interstellar Space,” NASA/JPL News, 4 November 2019, URL: https://www.jpl.nasa.gov/news/news.php?release=2019-218
5) Mara Johnson-Groh, ”Pressure Runs High at Edge of Solar System,” NASA, 8 October 2019, URL: https://www.nasa.gov/feature/goddard/2019/pressure-runs-high-at-edge-of-solar-system
6) ”A New Plan for Keeping NASA's Oldest Explorers Going,” NASA/JPL-Caltech News, 8 July 2019, URL:
7) ”Shaw Prize in Astronomy Awarded to Ed Stone,” NASA/JPL, 22 May 2019, URL: https://www.jpl.nasa.gov/news/news.php?feature=7408&utm_source=iContact&
8) Susannah Darling, Rob Garner, ”The Voyage to Interstellar Space,” NASA, 27 March 2019, URL: https://www.nasa.gov
9) Dwayne Brown, Karen Fox, Calla Cofield, ”NASA's Voyager 2 Probe Enters Interstellar Space,” NASA/JPL News Release 18-115, 10 December 2018, URL: https://www.jpl.nasa.gov/news/news.php?feature=7301
10) Andrew Warren, ”We're all ears as Voyager 2 goes interstellar,” CSIRO news, 11 December 2018, URL: https://www.csiro.au/en/News/News-releases/2018/Were-all-ears-as-Voyager-2-goes-interstellar
11) ”NASA's Deep Space Antenna Upgrades to Affect Voyager Communications,” NASA/JPL News, 4 March 2020, URL: https://www.jpl.nasa.gov/news/news.php?release=2020-044
The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates ([email protected]). | 0.862764 | 3.931396 |
Astronomers exploiting six years worth of data from ESA’s INTEGRAL mission have pinned down the individual processes contributing to the high-energy Galactic interstellar emission produced by cosmic-ray electrons. Deciphering each of the different physical mechanisms at play at hard X-ray and soft gamma-ray wavelengths represents a crucial step towards an increasingly detailed picture of the population of high-energy particles permeating the Milky Way.
Cosmic rays are highly-energetic charged particles that pervade galaxies, including our own Galaxy, the Milky Way, and can also escape from them and travel across intergalactic space. They are important players in regulating global galactic properties such as the heating balance and the total energy budget, and have been subject to intense investigation ever since their discovery in 1912.
Researchers study these particles either directly, by detecting the tracks that arise from collisions with material in the Earth’s atmosphere, or indirectly, by tracing the radiation emitted when cosmic rays interact with different components of a galaxy – for example, other particles, photons, magnetic fields. In the Milky Way, these phenomena are among the primary sources of the distinctive ‘diffuse’ emission that is seen along the Galactic Plane, at both the low energy (radio, microwave) and high energy (hard X-ray, gamma ray) ends of the electromagnetic spectrum.
This ‘glow’ is due to a combination of many different processes. Extensive observations across many wavelengths, as well as detailed physical modelling, are required to disentangle all contributions and to help solve the puzzle of the charged particles that fill our Galaxy.
“The diffuse emission at hard X-ray and soft gamma-ray wavelengths is an excellent tracer of cosmic-ray electrons and their antiparticles, the positrons, a minor but very significant fraction of the high-energy particle population in the Milky Way,” explains Laurent Bouchet from Université de Toulouse and Institut de Recherche en Astrophysique et Planétologie (IRAP) in France. Bouchet and his international team exploited data from ESA’s INTEGRAL mission, probing the entire sky at energies between 20 keV and 2.4 MeV. Exploring the diffuse emission in this energy range is one of the main science goals of the INTEGRAL mission, and after almost a decade of operation the mission has finally achieved the unprecedented sensitivity required to push this inquiry to the next level.
The study conducted by Bouchet and his collaborators relies on data collected with the Spectrometer on board INTEGRAL (SPI) over a time span of six years. “Such a long exposure allowed us to isolate, with very high precision, the different physical processes that account for the total emission in the spectral window probed by INTEGRAL,” he adds.
The first step in the complex analysis performed by the team consists of a careful scrutiny of the data to remove all point sources, both galactic and extragalactic, that radiate at these wavelengths. In this context, point sources represent a contamination of the diffuse signal produced by cosmic rays. “We have identified a few hundred sources across the entire sky and established that their contribution is dominant at the lowest energies examined in this work, between 20 and 100 keV,” notes Bouchet. After point-source removal, the observed diffuse emission was compared with model predictions, in order to break it down into the individual physical processes that contribute to it.
“Interestingly, we found a major contribution due to Inverse Compton (IC) scattering, thus confirming what early INTEGRAL data had hinted at a few years ago,” comments Andrew Strong from the Max-Planck Institut für Extraterrestrische Physik (MPE) in Germany. IC scattering consists of collisions between highly energetic electrons (or positrons) and low-energy photons present in interstellar space, which result in the electrons transferring part of their energy to the photons, thus ‘boosting’ them to X- and gamma-ray wavelengths. Cosmic-ray electrons interact via IC scattering with infrared and visible photons emitted by stars, and with the ubiquitous photons of the cosmic microwave background radiation.
The team made use of a very detailed model of the interstellar radiation field in the inner part of the Galaxy, a crucial ingredient to be taken into account in order to achieve a thorough physical interpretation of the observed emission. “Together with the latest models and improved data analysis techniques, the new INTEGRAL data allowed us to unequivocally identify IC scattering as the principal mechanism producing diffuse emission between 100 and 200 keV, as well as between 600 keV and 2 MeV,” adds Strong.
Besides the clear feature of IC scattering, the data also exhibit the well studied signatures of other emission processes arising in this spectral band – the annihilation of positrons with electrons and the radioactive decay of some unstable atomic nuclei. When positrons and electrons collide, two things may happen: they may destroy each other immediately, releasing a pair of photons each with an energy of 511 keV; alternatively, they may create an unstable and short-lived two-particle system called positronium, which soon decays into two or more photons, producing a distinctive continuum emission spectrum up to 511 keV. At energies above 1 MeV, the data also exhibit characteristic decay features of two unstable isotopes of aluminium (26Al) and iron (60Fe). This indicates the presence of these radioactive nuclei – the products of recent nucleosynthesis in supernova explosions – throughout the diffuse interstellar medium of the Milky Way.
“In addition to these mechanisms, the data require a further component to be taken into account at low energies, below 50 keV,” notes Bouchet. “This is most likely due to the superposition of many unresolved faint sources, as pointed out by previous studies based on data from the IBIS imager on board INTEGRAL,” he adds. Stars with very hot coronae and cataclysmic variable stars are the main objects contributing to this unresolved emission.
The study of Bouchet and collaborators enabled models of cosmic ray propagation to be tested in this portion of the electromagnetic spectrum in greater detail than previously possible. “The data demonstrate that our current understanding of the properties of cosmic-ray electrons in the Milky Way is qualitatively correct,” notes Strong. As INTEGRAL keeps scanning the high-energy sky, even longer exposures will be available in the future. “With more data and improved analysis methodology, we plan to explore quantitatively the distribution of cosmic-ray electrons across the Galaxy, narrowing down important parameters such as the size of the Galactic region within which the particles are confined,” he adds.
Ultimately, it is essential to verify that the data fit well within the physical scenario suggested by other observations. In particular, there is a consensus on the general picture provided by both INTEGRAL and the Large Area Telescope (LAT) on board NASA’s Fermi Gamma-ray Space Telescope. Sensitive to gamma rays between 20 MeV and 300 GeV, Fermi-LAT observes the sky at higher energies than INTEGRAL, and the agreement reached by these two complementary missions is very encouraging.
“This long-awaited result showcases INTEGRAL’s uniqueness in probing such a crucial spectral window,” comments Chris Winkler, INTEGRAL Project Scientist at ESA. “The large amount of data accumulated by INTEGRAL is now revealing the mission’s full potential for exciting results and discoveries.“
Note for Editors
The study presented here is based on observations performed with the Spectrometer on board INTEGRAL (SPI) between 22 February 2003 and 2 January 2009. The data probe the entire sky at energies between 20 keV and 2.4 MeV.
The data were compared to model predictions obtained with GALPROP, a publicly available code for calculating the propagation of cosmic-ray nuclei, antiprotons, electrons and positrons. The code also computes diffuse gamma-ray and synchrotron emission resulting from the cosmic rays. The first version of GALPROP was developed in the mid-1990s by Andrew W. Strong (MPE, Germany) and Igor V. Moskalenko (Stanford University, USA), both co-authors of the paper presented here. The code is currently maintained by a small team of researchers. In particular, GALPROP includes the most advanced model presently available of the interstellar radiation in the inner Galaxy, which has been developed by Troy A. Porter (Stanford University, USA), who is also a co-author of the paper presented here.
INTEGRAL is an ESA project with instruments and science data centre funded by ESA Member States (especially the Principal Investigator countries: Denmark, France, Germany, Italy, Spain, Switzerland) and Poland, and with the participation of Russia and the USA.
- Scientific paper : L. Bouchet, et al., “Diffuse Emission Measurement with the SPectrometer on Integral as an Indirect Probe of Cosmic-ray Electrons and Positrons“, 2011, The Astrophysical Journal, 739, 29
- Laurent Bouchet, Université de Toulouse and Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse, France, Email: [email protected], Phone: +33-561-55-86-03 | 0.881129 | 4.199074 |
A "DOOMSDAY" asteroid named after the Egyptian god of chaos could obliterate our planet in our lifetimes – and it's forced a gathering of some of the world's brightest scientists.
The runaway space rock Apophis is the size of seven London buses and will come worryingly close to our planet several times over the next century.
Some experts think the asteroid will hit our planet during one of these flybys, while others say the chances of impact are unlikely.
Apophis is being discussed this week by space scientists at the 2019 Planetary Defense Conference in Maryland, USA.
Among other issues, experts are discussing how best to study Apophis as it speeds past Earth on its next flyby on April 13, 2029.
The chat follows yesterday's warning from Nasa's top boss that a catastrophic asteroid strike on Earth could happen in our lifetime.
Apophis is expected to cruise harmlessly by Earth in 2029, soaring about 19,000 miles above the surface – within the distance that some satellites orbit Earth.
It's rare for an asteroid of this size to pass by Earth so close. When it does, Apophis will appear as a bright streak across the sky like a shooting star.
"The Apophis close approach in 2029 will be an incredible opportunity for science," said Nasa scientist Dr Marina Brozovi.
"We'll observe the asteroid with both optical and radar telescopes. With radar observations, we might be able to see surface details that are only a few meters in size."
Scientists are debating whether to use the unusual opportunity to send a spacecraft to the hurtling rock.
In particular, they're keen to check out how Earth's gravity affects Apophis's trajectory, spin and surface features.
The work could also help us defend ourselves from incoming asteroid strikes in future.
"Apophis is a representative of about 2,000 currently known Potentially Hazardous Asteroids," said Nasa near-Earth object boss Paul Chodas.
"By observing Apophis during its 2029 flyby, we will gain important scientific knowledge that could one day be used for planetary defence."
Since its discovery in 2004, Nasa and other scientists have closely tracked the path that Apophis takes around the Sun.
The readings help predict possible future collisions with Earth as it whips around the star – and scientists are split on the danger posed.
Recently, Russian scientists warned that Apophis, full name Apophis 99942, could smash into Earth at speeds of 15,000 miles per hour.
They said the doomsday rock's path around the Sun means there are "100 possible collisions between Apophis and the Earth, the most dangerous of them in 2068".
However, Nasa remains unconvinced.
"Current calculations show that Apophis still has a small chance of impacting Earth, less than 1 in 100,000 many decades from now," said Nasa's Dwayne Brown.
"Future measurements of its position can be expected to rule out any possible impacts."
What's the difference between an asteroid, meteor and comet?
Here's what you need to know, according to Nasa...
- Asteroid: An asteroid is a small rocky body that orbits the Sun. Most are found in the asteroid belt (between Mars and Jupiter) but they can be found anywhere (including in a path that can impact Earth)
- Meteoroid: When two asteroids hit each other, the small chunks that break off are called meteoroids
- Meteor: If a meteoroid enters the Earth's atmosphere, it begins to vapourise and then becomes a meteor. On Earth, it'll look like a streak of light in the sky, because the rock is burning up
- Meteorite: If a meteoroid doesn't vapourise completely and survives the trip through Earth's atmosphere, it can land on the Earth. At that point, it becomes a meteorite
- Comet: Like asteroids, a comet orbits the Sun. However rather than being made mostly of rock, a comet contains lots of ice and gas, which can result in amazing tails forming behind them (thanks to the ice and dust vapourising)
On Monday, Nasa boss Jim Bridenstine called for a global study to be urgently launched into the threat posed to humanity by a large asteroid collision.
And the Nasa administrator called for world powers to begin preparations for the impact of meteor events right away.
Mr Bridenstine said: "We have to make sure that people understand that this is not about Hollywood, it's not about the movies.
"This is about ultimately protecting the only planet we know, right now, to host life and that is the planet Earth"
TOP STORIES IN SCIENCE
In other space news, Nasa's Parker Solar Probe is currently "plunging into the Sun" at 213,000mph as part of a bold investigation into our solar system's star.
The space agency is also on course to find alien life within next few decades – but warns we’re "unlikely to shake hands with them".
And Nasa is hoping to send astronauts back to the Moon by 2024.
Are you worried about asteroid strikes? Let us know in the comments! | 0.836188 | 3.125502 |
Crescent ♊ Gemini
Moon phase on 2 April 2006 Sunday is Waxing Crescent, 4 days young Moon is in Gemini.Share this page: twitter facebook linkedin
Previous main lunar phase is the New Moon before 4 days on 29 March 2006 at 10:15.
Moon rises in the morning and sets in the evening. It is visible toward the southwest in early evening.
Moon is passing about ∠7° of ♊ Gemini tropical zodiac sector.
Lunar disc appears visually 2.4% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1873" and ∠1919".
Next Full Moon is the Pink Moon of April 2006 after 11 days on 13 April 2006 at 16:40.
There is low ocean tide on this date. Sun and Moon gravitational forces are not aligned, but meet at big angle, so their combined tidal force is weak.
The Moon is 4 days young. Earth's natural satellite is moving from the beginning to the first part of current synodic month. This is lunation 77 of Meeus index or 1030 from Brown series.
Length of current 77 lunation is 29 days, 9 hours and 29 minutes. This is the year's shortest synodic month of 2006. It is 13 minutes shorter than next lunation 78 length.
Length of current synodic month is 3 hours and 15 minutes shorter than the mean length of synodic month, but it is still 2 hours and 54 minutes longer, compared to 21st century shortest.
This New Moon true anomaly is ∠19°. At beginning of next synodic month true anomaly will be ∠38.4°. The length of upcoming synodic months will keep increasing since the true anomaly gets closer to the value of New Moon at point of apogee (∠180°).
5 days after point of perigee on 28 March 2006 at 07:13 in ♓ Pisces. The lunar orbit is getting wider, while the Moon is moving outward the Earth. It will keep this direction for the next 7 days, until it get to the point of next apogee on 9 April 2006 at 13:16 in ♌ Leo.
Moon is 382 614 km (237 745 mi) away from Earth on this date. Moon moves farther next 7 days until apogee, when Earth-Moon distance will reach 405 551 km (251 998 mi).
4 days after its ascending node on 29 March 2006 at 03:31 in ♈ Aries, the Moon is following the northern part of its orbit for the next 9 days, until it will cross the ecliptic from North to South in descending node on 12 April 2006 at 02:35 in ♎ Libra.
4 days after beginning of current draconic month in ♈ Aries, the Moon is moving from the beginning to the first part of it.
10 days after previous South standstill on 22 March 2006 at 16:53 in ♐ Sagittarius, when Moon has reached southern declination of ∠-28.725°. Next day the lunar orbit moves northward to face North declination of ∠28.715° in the next northern standstill on 4 April 2006 at 07:35 in ♋ Cancer.
After 11 days on 13 April 2006 at 16:40 in ♎ Libra, the Moon will be in Full Moon geocentric opposition with the Sun and this alignment forms next Sun-Earth-Moon syzygy. | 0.848363 | 3.221715 |
You can be happy that we orbit a placid, primary series, yellow dwarf star. Astronomers just recently spied an enormous superflare on a small star, an effective, radiation gushing occasion that you would not wish to witness up close.
The ‘star’ was ULAS J22494013-0112369, an L-type sub-stellar brown dwarf near the Aquarius-Pisces border. The troublesome, phone number-style name originates from the UKIDSS Big Location Study (ULAS) research study searching for dwarf stars, plus the things’s position in the sky in best ascension and declination. Found 248 light-years remote, ULAS J2249-0112(for brief) weighs in at simply around 15 Jupiter masses, with a radius about a 1/10 th that of our Sun; any tinier, and it would not even rank as a sub-stellar brown dwarf.
The action started on the night of August 13, 2017, as the Next Generation Transit Study (NGTS) was searching the sky for exoplanets. Based at the Paranal Observatory complex in the Atacama desert, NGTS is a wide-field study with 12 telescopes, imaging a 96 square degree swath of sky as soon as every 13 seconds on the hunt for transiting exoplanets. While these sorts of transit occasions include small modifications in brightness, what ULAS J2249-0112 produced was anything however. The faint +245 th magnitude dwarf briefly flared over 10 magnitudes in brightness for 9.5 minutes, reaching a peak magnitude of +14 That’s a modification of brightness of 10,000- fold.
” NGTS has 10s to numerous.
countless stars in its field of vision at any one time, which offers.
us the exact same quantity of light curves,” James Jackman (Warwick.
University) informed Universe Today “So, in addition to browsing.
for worlds in this information we can look for other astrophysical.
occasions, such as excellent flares.”.
This dazzling white light flare was over 10 times brighter and more effective than anything seen on our Sun. The Fantastic Carrington superflare of 1859, for instance, released an effective flare that set telegraph workplaces aflame and sent out vibrant auroral screens as far south as the Caribbean. The 2017 exoflare would have signed up as an X-100 class occasion, were it to have actually taken place on our Sun.
” As the star is so faint, we might just see it when it was flaring,” states Jackman. “So, the majority of our light curve sits at a count rate of absolutely no. Then when the flare takes place, it unexpectedly surged up!”
The research study was released in the April 2019 Regular Monthly Notifications of the Royal Astronomical Society: Letters
This occasion reveals that even small L-dwarfs can load a huge punch. Though bigger, tempestuous red overshadows are popular manufacturers of flares, a flare on a smaller sized L-type brown dwarf is uncommon. The 2017 occasion was just the 6th such occasion observed from a L-dwarf, and the 2nd caught from the ground. Of these, the 2017 occasion was the most effective such occasion observed so far.
” Flares are produced through.
reconnection occasions in the electromagnetic fields of stars,” states Jackman.
” The energy launched is supplied by the electromagnetic field, so a.
more powerful field offers high energy flares. M stars in specific can.
have really strong electromagnetic fields, which leads to high energy.
flares. We have actually observed that after a point as we go to smaller sized stars,.
they end up being less active. This refers the electromagnetic field.
getting weaker, producing less high energy flares. The existence of a.
big flare on our extremely little star is a bit perplexing, as it.
recommends that these small stars can hold large quantities of energy in.
their electromagnetic fields after all.”.
The NGTS group continues to search the information, searching for more superflares. The Transiting Exoplanet Study Satellite(TESS) might likewise show to be a bonanza of such occasions, as it performs its all-sky study for neighboring transiting exoplanets.
” We’re presently running a devoted.
study to look for M and L dwarf flares in the NGTS dataset,”.
states Jackman. “Other groups are likewise targeting neighboring brilliant stars.
to attempt and get info not simply on flares themselves, however how.
they might be connected to the quiescent habits also (e.g.
starspots). It’s an actually amazing time to be in the field.”
And naturally, such an effective superflare would be lethal to life as we understand it. When it comes to life on worlds orbiting red or brown overshadows, the best locations are on the far hemisphere of a tidally locked world, or maybe in a subsurface ocean, either of which would be safeguarded from life-sterilizing radiation. On the plus side, such stars are parsimonious, taking trillions of years to burn through the combination cycle. (longer than the present age of deep space) providing prospective life on a world orbiting a red or brown dwarf great deals of time to progress.
Though brown overshadows can not sustain.
standard hydrogen combination by means of the proton-proton chain of excellent.
nucleosynthesis, they can obtain energy from a few of the really initially.
actions in the procedure by means of deuterium and lithium combination.
And while we’re experiencing such an enormous superflare on a far star, our own star the Sun has actually been anything however active, as we approach another extensive solar minimum in between solar cycle #24 and #25 in late 2019 and 2020.
Be happy we aren’t subjected to such a penalizing superflare like those produced by smaller sized dwarf stars … it may simply be why we progressed here in the very first location.
Did you understand: though they’re the most typical kind of star in deep space, not one red dwarf shows up to the naked eye? Take a look at our list of red dwarf stars for yard scopes. | 0.882504 | 3.792329 |
Gemini South DSSI image of star pair occulted by Orcus’ satellite Vanth. Image reveals bright primary star in the center of the image and a companion at upper right (approximately 2:00 position). The other “star” at lower left (8:00 position) is an artifact of processing. This image consists of 1000 seconds of data subtracted to remove atmospheric distortions to reveal the close binary pair responsible for the Vanth double occultation.
Extremely high-resolution speckle observations by Gemini South deliver critical details on a star (or stars) lying in the apparent path of remnants from the early formation of our Solar System.
In early March of 2017 the outer Solar System object Orcus, and its one known satellite Vanth, were on an apparent collision course with a star – at least that’s the way it appeared from our perspective on Earth. Original calculations showed that Orcus would pass in front of a relatively bright star and temporarily block the star’s light. However, later refinements to the calculations revealed that the shadow of Vanth would trace a path across the Earth’s surface.
These events, known as occultations, are only visible from a thin swath on Earth’s surface and calculations have small uncertainties due to observations of the orbits and estimates of the objects’ size. But even with these uncertainties, what happened surprised astronomers.
Because of these uncertainties observations were conducted by five telescopes distributed geographically to be sure to catch the event. While neither of the Gemini telescopes were scheduled to observe the occultation, Gemini was called into action when the coordinated observations detected two separate, non-simultaneous occultations by widely separated telescopes. The detections were made by the NASA Infrared Telescope Facility on Maunakea, and the Las Cumbres 1-meter telescope at the McDonald Observatory in Texas.
Based on the observations, and earlier Hubble Space Telescope observations, the team ruled out the possibility of another yet-undiscovered satellite. The separation of the events also precluded Vanth or Orcus from being responsible for both occultations.
Following the recommendation of an external reviewer of the submitted paper on the work, team member Amanda Bosh of the Massachusetts Institute of Technology asked for Fast Turnaround time on the Gemini South telescope in Chile. These observations would scrutinize the star in extremely high resolution and look for a yet unseen companion which could explain the double occultation. A visiting instrument, called the Differential Speckle Survey Instrument (DSSI), would be used due to its powerful ability to resolve stars in exquisite detail.
DSSI uses a technique called “speckle imaging,” which takes thousands of very quick exposures that can capture fine details, including artifacts due to atmospheric blurring. By averaging out the effects of the ever-changing atmospheric turbulence, what remains is an ultra-sharp image of the stars in the field. When this technique was applied to the target star for this occultation, the result was clear: the star was a double and separated by only 250 milliarcseconds from each other (comparable to separating two automobile headlamps from approximately 600 miles, or 1,000 kilometers, away). Furthermore, the alignment of the star pair fit the paths of the occultations, proving that Vanth was observed to occult the two different stars from the two different sites. Mystery solved!
“Without the high-resolution data provided by Gemini, we would not have been able to accurately determine which body occulted which star(s). Speckle imaging is a powerful technique, and it ensured correct interpretation of these stellar occultation data,” said Amanda Sickafoose, lead author on the published results.
Stellar occultations provide an extremely reliable way to determine the sizes of distant Solar System objects so these observations were critical in refining the size of Vanth. Amanda Sickafoose adds, “Occultations are extremely sensitive to atmospheres and our results place a limit of a few microbars for any possible global atmosphere on Vanth.” From other observations astronomers also estimate that Orcus has a diameter of about 900 kilometers and the new occultation measurements from this work show that Vanth’s diameter is about 450 kilometers which is almost double the previously estimated size. The pair are known as trans-Neptunian objects (TNOs) which are thought to be remnants from the formation of our Solar System. Orcus and Vanth orbit in the outer Solar System in resonance with Neptune and in an orbit similar to Pluto in distance from the Sun, but in a position about 180 degrees from Pluto relative to the Sun. “This is why the Orcus system is sometimes described as an ‘anti-Pluto’,” said Sickafoose.
DSSI has visited both Gemini telescopes several times, thanks to the instrument’s Principal Investigator (PI) Elliott Horch of Southern Connecticut State University. Based on the instrument’s success, two updated versions of DSSI are slated for Gemini, one on Gemini North (called ‘Alopeke, Hawaiian for fox, which is already in use), and at Gemini South (called Zorro, Spanish for fox, which is slated for installation in early 2019). Steve Howell of NASA’s Ames Research Center serves as PI for both of these new instruments.
The paper describing these observations was led by Amanda A. Sickafoose of the South African Astronomical Observatory and the Massachusetts Institute of Technology. The paper has been published in Icarus and the preprint is available at: https://arxiv.org/abs/1810.08977.
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A podcast about Gemini Observatory and its role in the Era of Multi-Messenger Astronomy. Featuring news related to multi-messenger astronomy (MMA), time-domain astronomy (TDA), our visiting instrument program, and more through interviews with astronomers, engineers, and staff both here at Gemini (North and South) and abroad. | 0.860331 | 3.934582 |
At least once in its past, Earth existed as a roiling ball of molten rock that might have had the consistency of room-temperature oil, but would been untouchable at some 2,000 degrees Fahrenheit.
As magma oceans ebbed and flowed, the tumult might have launched elements conducive for life out of the rock and into our atmosphere. Researchers previously thought that maybe similar fluid dynamics — and the resulting spewing of life-supporting materials — likewise happened on Mars. But new research suggests that's not the case.
“We’ve had so little time to think about how a planet would evolve without a melting step, it’s hard to tell if this is a net positive or net negative for [the possibility of] life,” says Francis McCubbin, a NASA national materials coordinator and researcher who co-authored the new research.
By studying meteorites that came from Mars, McCubbin and his colleagues determined that the planet hosts two regions where the rock contains different ratios of hydrogen varieties. If the planet had once been awash in liquid rock, the same ratio of hydrogen types would be found all over the place, the team concluded in their Nature Geoscience paper.
Hydrogen analysis is one way to figure out whether Mars ever had a global magma ocean, McCubbin says. Other, yet-unstudied chemical systems on the planet could reveal ocean formation. That’s part of why McCubbin says it’s too early to consider this finding a thumbs-down for the possibility of life on Mars — and why their team plans to keep looking for signs of a once-liquid planet.
Goodness Gracious, Great Balls of Magma
Before our solar system had planets, it had dust and gas. When those particles started clumping together, researchers think the clumps collided again and again until entire planets formed. Eventually, the clusters melted into an ocean of magma. Like a blender mixing strawberries and bananas into a smoothie, liquifying would swirl all the deposits from the early solar system together. The process would also churn material from inside the planet core and release it into the atmosphere, McCubbin says, including elements and chemicals necessary for life.
McCubbin and his colleagues, including first author Jessica Barnes, a University of Arizona cosmochemist whom McCubbin calls a “rock star” in the field, studied whether that potentially life-giving magma formed by first looking at two meteorites. These rock chunks are pieces of Mars’ surface, or crust, that crash-landed in Africa and Antarctica. Researchers have calculated that one last interacted with martian water 3.9 billion years ago, and the other 1.5 billion years ago.
McCubbin and his team found that there are different versions of hydrogen in those two rocks, and that the proportions of each element variety are similar. A comparable hydrogen ratio also appears in more recent examinations of the planet’s crust, including in data from the Mars rover Curiosity. When the team compared all this information to Mars meteorites that originated from a deeper rocky layer in the planet, however, they saw something else. The hydrogen ratios in the deeper samples didn’t share the same ratio.
Other Clues of Planetary Churning
Two mixes of hydrogen varieties suggest two spots of water formation on Mars that didn’t ever meet, and that subsurface, molten churns never happened. “A lot of what could have nurtured life in the atmosphere didn’t get there — maybe,” McCubbin says.
There are other ways material from the core of Mars could have reached the atmosphere, like constant volcanic activity or hydrothermal vents, McCubbin says. Additionally, planetary scientists need to look at other chemicals on Mars and see if they counter the hydrogen finds and support the concept of a magma ocean.
This research project relied heavily on studies from a range of meteorites — “it was sort of fortuitous that we could take a lot of data and compare them to our crustal samples,” McCubbin says. Future work will need to keep analyzing a whole suite of Mars samples. But don’t worry: NASA adds new Mars meteorites to their collection on a regular basis, McCubbin says. We’re retrieving more from Mars, too. The Perseverance rover will hit the planet to search for life in 2021, while another project might bring rock samples back a decade later.
If all goes according to plan, the team won’t be running low on samples to help them assess the Red Planet’s past anytime soon. | 0.830061 | 3.975449 |
Back in the days when Clyde Tombaugh was using a blink comparator to search for ‘Planet X,’ finding a new object in the outer Solar System was highly unusual. Uranus had been found in 1781, Neptune in 1846, and I suppose I should add Ceres in 1801, although it’s a good deal closer than the other two. The real point is that the Solar System seemed straightforward in Clyde Tombaugh’s day. There were eight planets and an asteroid belt. It wouldn’t be until 1943 that Kenneth Edgeworth argued that the outer system might have ‘a very large number of comparatively small bodies,’ with Gerard Kuiper publishing his own speculations in 1951.
Estonian astronomer Ernst Öpik first described what we now know as the Oort Cloud in 1932, with Jan Oort, a Dutch astronomer, reviving the idea in 1950. The Oort Cloud was a way to explain why comets behave the way they do. Oort believed that there must be a cometary ‘reservoir’ far away from the Sun — he chose 20,000 AU as a likely range because of the number of long period comets with aphelia at approximately that distance. Moreover, long-period comets seemed to come from all directions of the sky. As we’ve refined the idea and the numbers, we’ve begun to see just how vast the Solar System really is.
None of this is to take anything away from the discovery of the small world called V774104, announced yesterday at the Division for Planetary Sciences meeting in Washington, DC. Astronomer Scott Sheppard (Carnegie Institution for Science) and Chad Trujillo (Gemini Observatory, HI) have found a world 15.4 billion kilometers out, which works out to 103 AU and makes V774104 the most distant dwarf planet known, fully three times further from the Sun than Pluto. In Tombaugh’s day, such a discovery would have been front page news. Today we’ve come to assume that there are a lot of dwarf worlds out there, and expectations are that as our equipment improves, we’ll find plenty more.
Image: A dot moving (slowly) across background stars, V774104 was found about 15 degrees off the ecliptic. Credit: Subaru Telescope by Scott Sheppard, Chad Trujillo, and David Tholen.
V774104 is currently estimated to be between 500 and 1000 kilometers in diameter, less than half Pluto’s size. Just how significant it is in the larger scheme of things has yet to be determined because we’re not yet sure about the parameters of its orbit. Is it, at 103 AU, close to aphelion, and will it eventually swing back toward Neptune, making its orbit the likely result of a gravitational encounter with that planet? Or is V774104 actually something far more unusual, a world similar to Sedna and VP113 in being a possible member of the inner Oort Cloud?
Neither Sedna nor VP113 comes close enough to the Sun to experience gravitational effects from the giant planets. In fact, both stay outside 50 AU, thought to be the outer edge of the Kuiper Belt, and have aphelia as distant as 1000 AU. Colin at the Armagh Planetarium site notes the problem in V774104: Could a Dark World Put a New Light on Solar System History?:
…the current highly elliptical orbits of Sednoids cannot be their original orbits, the chance of smaller bodies in such eccentric paths accreting into objects hundreds of kilometres across is fantastically low. Sednoids must have originally formed in relatively circular orbits, possibly in the Oort Cloud.
So how did they get where they are today? One possibility to explain their orbits is that they reflect conditions in the Solar System’s infancy, when the young Sun was in a local environment rich in nearby stars. The other possibility is one that Percival Lowell would have loved. There may be a large, rocky planet out there that has elongated previously circular orbits.
The data from the 8-meter Subaru instrument in Hawaii that produced V774104 have also yielded a number of other objects roughly 80 to 90 AU from the Sun, all of which will need lengthy follow-up study to clarify the nature of their orbits. Like V774104, any of these might join Sedna and VP113 in never coming closer to the Sun than 50 AU. We may be about to see a surge in the numbers of dwarf worlds in this unusual category. Explaining why a region once thought to be empty is not should occupy astronomers and theorists for years to come. | 0.90131 | 3.740324 |
Hubble Space Telescope astronomers are tracking an invisible hydrogen gas cloud that is aimed back toward earth at nearly 700,000 miles per-hour. Though there are hundreds of gas clouds in our galaxy, the “Smith Cloud” is unique because astronomers know its trajectory … Earth. Do we need to evacuate?
Named after doctoral astronomy student Gail Smith, who detected radio waves emitted by the cloud in the 1960’s, Hubble scientists have observed that the cloud was most likely ejected from our Milky Way Galaxy 70 million years ago.
Team Leader Andrew Fox of the Space Telescope Science Institute in Baltimore explained in a press release,
The cloud is an example of how the galaxy is changing over time. It’s telling us that the Milky Way is a bubbling, very active place where gas can be thrown out of one part of the disk and then return back down to another.
The gas cloud is comet-shaped and estimated to be 11,000 light-years long and 2,500 light-years across. It is 30 times bigger than a full moon. Its chemical composition was determined using Hubble’s Cosmic Origins Spectrograph to measure how much light filtered through the cloud.
It was determined that the cloud is rich in sulfur, as is the Milky Way’s outer disk, a region about 40,000 light-years from the galaxy’s center and about 15,000 light-years farther out than our sun and solar system. Thus, the cloud was most likely launched from within the Milky Way. It’s coming home!
When the giant gas cloud returns to our solar system, it may result in a massive burst of star formation, creating as many as two million suns.
No need to worry. The collision is expected to occur in 30 million years. | 0.8998 | 3.420372 |
For billions of years, Earth has rotated in the same direction as the sun — but what if that direction were reversed?
Deserts would cover North America, arid sand dunes would replace expanses of the Amazon rainforest in South America, and lush, green landscapes would flourish from central Africa to the Middle East, according to a computer simulation presented earlier this month at the annual European Geosciences Union General Assembly 2018 in Austria.
In the simulation, not only did deserts vanish from some continents and appear in others, but freezing winters plagued western Europe. Cyanobacteria, a group of bacteria that produce oxygen through photosynthesis, bloomed where they never had before. And the Atlantic Meridional Overturning Circulation (AMOC), an important climate-regulating ocean current in the Atlantic, faded away and resurfaced in the northern Pacific Ocean, scientists reported at the conference. [What If the World Stopped Turning?]
During Earth's yearlong orbit around the sun, our planet completes a full rotation on its axis — which runs from the North Pole to South Pole — every 24 hours, spinning at a rate of about 1,040 mph (1,670 km/h) as measured at the equator. Its rotation direction is prograde, or west to east, which appears counterclockwise when viewed from above the North Pole, and it is common to all the planets in our solar system except Venus and Uranus, according to NASA.
As Earth rotates, the push and pull of its momentum shapes ocean currents, which, along with atmospheric wind flows, produces a range of climate patterns around the globe. These patterns carry abundant rainfall to humid jungles or divert moisture away from rain-parched badlands, for example.
To study how Earth's climate system is affected by its rotation, scientists recently modeled a digital version of Earth spinning in the opposite direction — clockwise when viewed from above the North Pole, a direction known as retrograde, Florian Ziemen, co-creator of the simulation and a researcher with the Max Planck Institute for Meteorology in Germany, told Live Science in an email.
"[Reversing Earth's rotation] preserves all major characteristics of the topography like sizes, shapes and positions of continents and oceans, while creating a completely different set of conditions for the interactions between the circulation and the topography," Ziemen said.
This new rotation set the stage for ocean currents and winds to interact with the continents in different ways, generating entirely new climate conditions around the world, the researchers reported in a project overview.
To simulate what would happen if Earth were to spin backward (retrograde instead of prograde), they used the Max Planck Institute Earth System Model to flip the sun's rotational path — and thereby flip Earth's rotation — and reverse the Coriolis effect, an invisible force that pushes against objects traveling over a rotating planet's surface.
Once those alterations were in place and the model showed Earth spinning in the opposite direction, the researchers observed the changes that emerged in the climate system over several thousand years, as feedback among the rotation, atmosphere and ocean went to work on the planet, the scientists wrote in a description of the work, which they are currently preparing for publication.
Overall, the researchers found that a backward-spinning Earth was a greener Earth. Global desert coverage shrank from about 16 million square miles (42 million square kilometers) to around 12 million square miles (31 million square km). Grasses sprouted over half of the former desert areas, and woody plants emerged to cover the other half. And this world's vegetation stored more carbon than our forward-spinning Earth, the researchers discovered.
However, deserts emerged where they never had before — in the southeastern U.S., southern Brazil and Argentina, and northern China.
Turn, turn, turn
The change in rotation also reversed global wind patterns, bringing temperature changes to the subtropics and midlatitudes; continents' western zones cooled as eastern boundaries warmed, and winters became significantly colder in northwestern Europe. Ocean currents also changed direction, warming seas' eastern boundaries and cooling their western ones.
In the simulation, AMOC— the ocean current responsible for transporting heat around the globe — disappeared from the Atlantic Ocean, but a similar and slightly stronger current arose in the Pacific, carrying heat into eastern Russia. This was somewhat unusual, as a prior study that modeled a reverse-spinning Earth did not see this change, Ziemen told Live Science in an email.
"But as the AMOC is the result of many complex interactions in the climate system, there can be a lot of reasons for this difference," he said. [Earth Pictures: Iconic Images of Earth from Space]
Altered sea currents in the Indian Ocean also allowed cyanobacteria to dominate the region, which they have never managed to accomplish while the Earth spins in its current direction, the researchers discovered.
But for Ziemen, the greening of the Sahara was the most intriguing change that appeared in their "backward" model of Earth.
"Seeing the green Sahara in our model got me thinking about the reasons why we have a desert in the Sahara, and why there is none in the retrograde world," Ziemen said. "It is this thinking about the most basic questions that fascinates me about the project."
Original article on Live Science. | 0.825618 | 3.257704 |
Rainbow Music was born from this curiosity, asking the simple questions about the connections from above and below and looking for the most elegant and simple answer.
Fundamentally everything in the universe from the vastness of the galaxies to the smallest atoms and beyond are all connected through vibration. Everything vibrates or oscillates, even us. Take the orbit of the earth around the sun. The earth travels around the sun covering vast distances or length and does it on a regular basis or frequency, i.e. Every 365~ days. The same can be said about the how the Moon travels around the earth and does it more frequently, every 28 days.
These two concepts of space and time are connected and proportional, the greater the frequency the shorter the length.
In the sciences this is known as Wave Length and Frequency and it applies from the very very large to the very very small.
Armed with this most basic insight we just need to look now for the natural relationship between all things and one of these is the natural relationship between sound and color.
If we look at the most commonly accepted view of these two natural forces (light / sound) here’s what you will see.
First let’s look at light.
So what is a THz you might ask? Well the Hz means cycles (vibrations) per second with 1Hz being 1 cycle per second and the (T) in THz means “Billion” so 400-484 Billion Cycles per Second. That’s really fast! The cycles per second are called Frequency as shown on the chart.
So each color (Red, Orange, Yellow, Green, Blue, (Indigo) and Violet) have their own frequency. If the frequency changes the color changes.
OK now let’s look at sound and in particular Harmonic Sound.
|Music Note||Tuning Frequency (Hz)|
|G# – A♭||830|
|F# – G♭||739|
|D# – E♭||622|
|C# – D♭||554|
|A# – B♭||466|
Just like the light frequencies, in order for the Note A to be the Note A it needs to be in a specific range around 440Hz. We have not always tuned to 440Hz in fact in ancient times we tuned A at 432 Hz and then evenly spaced the tones both up and down.
We believe that the tuning of A 432Hz is a more natural tuning point but for the sake of this discussion it doesn’t matter that much.
Spend a minute and compare the Frequencies of the Musical Notes here to the Frequencies of light above.
Let’s now bring the two together for you, connecting Music to Color.
|Music Note||Sound (Hz)||Color||Light (THz)|
You can see from the table on the left that the Frequencies of the Sounds and the Frequencies of Light are a perfect natural connection. Move either the sound or the color just a small amount and they are no longer that sound or color.
Is this an accident or coincidence, we say absolutely not. They are a natural harmonic of each other.
The similarities are simply fascinating!
There are 7 main colors identified in the rainbow.
Red, Orange, Yellow, Green, Blue, Indigo and Violet
and there are 7 whole tones in Music.
A, B, C, D, E, F, G
There are 5 transition points between the 7 colors.
Red-Orange, Yellow-Green, Green-Blue, Indigo-Violet, Violet- None Visible
and there are 5 Flat / Sharp notes in the Music Scale.
A#/B♭, C#/D♭, D#/E♭, F#/G♭ & G#/A♭
7 Whole Notes & Colors and 5 transition Notes & Colors both have a total 12
The difference between visible light (THz) and harmonic sound (Hz) is exactly 1 billion or 12 zeros or 1012
The similarities continue even further when you look closely, even more so when A 432Hz tuning is used, creating a perfect lock between the two, leading further to natural math and geometry.
So it can easily be said that the color red is the same as the note A just at a different pitch. And of course this applies to all other notes too.
This basic insight gives us great freedom to explore the connection between the heavens and earth and gives us the tools to be able to make music from our natural surroundings. It shouldn’t come as a great surprise then that the Indigenous Australian instrument the Didgeridoo has a base pitch of D (Green). Eg. see Green trees play (D) Green.
This understanding continues to extend, only limited by imagination and ones ability to interrupt the natural environment whilst being able to create art that not only looks beautiful but also has harmonious sounds or melody.
Here are just a couple of simple examples that our children can learn and apply to bring greater depth and meaning into the things they learn and do. They illustrate in a simple form just a couple of ways that both Visual Art, Fashion and Music can now be connected.
Connecting Music to Color through Art and Fashion
This leads us to the Question, Why is Connecting Music to Color Important? The best way to answer this is to loosely define Rainbow Music.
What is Rainbow Music?
Rainbow Music is an accelerated learning sensory based programme. It explores and expresses the natural harmonic relationship between light and sound, the colors of the rainbow and musical notes and chords. It has benefits in painting, the arts, composing your own music, fashion and design, health, dance and the sciences including, math, geometry and astronomy. It requires no knowledge of music and has no age restrictions. It is designed for all to enjoy.
This is the greatest gift we can give to you and it is not in the answers to questions that we might ask but in the questions you ask and the journey you take to discover these answers. In many ways the music is a by product of these fundamental understandings, as you already have everything you need to be able to explore and discover this for yourself. It has taken us years to bring these insights into a cohesive Music Programme and we don’t want it to be a long road for you, in fact we have produced Rainbow Music as a short cut in your Music journey. We urge you not to forget its origins and to appreciate that Rainbow Music is a means or bridge not a destination. We hope that through the Rainbow bridge we can provide a shinning light that will guide you to re-discover the roots of music and use this to re-connect with your past, present and future in all forms of artistic and creative expression. Music and many other creative art forms have been used for millennia to build strong and closely connected cultures and to include and participate in the many flowers of life. It is your role amongst this to enjoy the flower in all it’s beauty and imperfections and be willing to share it with everyone you can. | 0.842546 | 3.470886 |
If you look skyward on a clear moonless night, you can immediately see that you and all of your fellow Earthlings live in a galaxian universe. Indeed, almost all of the celestial objects that you can see with your unaided eye reside within the Milky Way – our galactic home. From pin-point stars of multiple hues to hazy nebulae and silhouetting dust clouds, the myriad denizens of our Galaxy collectively trace a vast self-gravitating system that whirls about the supermassive black hole in its center while percolating in continual self-transformation
Just beyond the Milky Way, the Large and Small Magellanic Clouds can be readily spotted from the Earth’s southern hemisphere. These companions (or victims) of the much larger Milky Way are but the biggest and brightest of the 15-odd galaxies that are currently known to be buzzing around us. Residents of Earth’s northern hemisphere who can get away from sources of light pollution can enjoy naked-eye and binocular views of the more distant Andromeda Galaxy. Similar in girth to the ponderous Milky Way, the “Great Nebula in Andromeda” rules over its own bevy of dwarf satellites some 2.5 million light-years away from our home system.
Amateur telescopes can reveal thousands of other galaxies in those sections of the sky that are sufficiently far from the Milky Way’s congested disk The digital images of elliptical, spiral, irregular, and interacting galaxies that these “citizen scientists” can now obtain surpass the best images obtained professionally just 25 years ago. Beginning in 1995, the Hubble Space Telescope was trained on seemingly empty patches of the sky for exceptionally long exposures lasting 10 or more hours each. The resulting Hubble Deep Fields in the northern and southern hemispheres and the more recent Hubble Ultra Deep Fields have shown galaxies upon galaxies to the edge of detectability.
In these images, we can behold galaxies so distant that we see them as they were more than 10 billion years ago – shortly after they had formed from the chaos of the Hot Big Bang. Looking locally, we can see that our home galaxy has evolved to the point, where sentient life has overrun the moist surface of one rocky planet that is in orbit around one particular but unremarkable star. We are left wondering how all this played out. Indeed, understanding the structure, content, and natural histories of these diverse realms has challenged our best astronomical minds while motivating the development of ever more powerful telescopes and sensitive instrumentation. In many ways, our galaxian adventures have just begun.
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All contributions will be vetted for appropriate content and edited for clarity. All contributions that are published in The Galactic Inquirer are the property of the author(s) and The Galactic Inquirer. Therefore, subsequent use of published contributions must follow “fair use” guidelines, including written permission from the author(s) and explicit attribution to the author(s) and The Galactic Inquirer. | 0.902824 | 3.910441 |
Tuesday, January 14, 2020
“Cold Neptune” and two temperate super-Earths found orbiting nearby stars
Washington, DC— A “cold Neptune” and two potentially habitable worlds are part of a cache of five newly discovered exoplanets and eight exoplanet candidates found orbiting nearby red dwarf stars, which are reported in The Astrophysical Journal Supplement Series by a team led by Carnegie’s Fabo Feng and Paul Butler.
The two potentially habitable planets are orbiting GJ180 and GJ229A, which are among the nearest stars to our own Sun, making them prime targets for observations by next-generation space- and land-based telescopes. They are both super-Earths with at least 7.5 and 7.9 times our planet’s mass and orbital periods of 106 and 122 days respectively.
The Neptune-mass planet—found orbiting GJ433 at a distance at which surface water is likely to be frozen—is probably the first of its kind that is a realistic candidate for future direct imaging.
“GJ 433 d is the nearest, widest, and coldest Neptune-like planet ever detected,” Feng added.
The newfound worlds were discovered using the radial velocity method for finding planets, which takes advantage of the fact that not only does a star’s gravity influence the planet orbiting it, but the planet’s gravity also affects the star in turn. This creates tiny wobbles in the star’s orbit that can be detected using advanced instruments. Due to their lower mass, red dwarfs are the primary class of stars around which terrestrial mass planets can be found using this technique.
Cooler and smaller than our Sun, red dwarfs—also called M dwarfs—are the most common stars in the galaxy and the primary class of stars known to host terrestrial planets. What’s more, compared to other types of stars, red dwarfs can host planets at the right temperature to have liquid water on their surfaces on much closer orbits than those found in this so-called “habitable zone” around other types of stars.
“Many planets that orbit red dwarfs in the habitable zone are tidally locked, meaning that the period at which they spin around their axes is the same as the period at which they orbit their host star. This is similar to how our Moon is tidally locked to Earth, meaning that we only ever see one side of it from here. As a result, these exoplanets are a very cold permanent night on one side and very hot permanent day on the other—not good for habitability,” explained lead author Feng. “GJ180d is the nearest temperate super-Earth to us that is not tidally locked to its star, which probably boosts its likelihood of being able to host and sustain life.”
The other potentially habitable planet, GJ229Ac is the nearest temperate super-Earth to us located in a system in which the host star has a brown dwarf companion. Sometimes called failed stars, brown dwarfs are not able to sustain hydrogen fusion. The brown dwarf in this system, GJ229B, was one of the first brown dwarfs to be imaged. It is not known if they can host exoplanets on their own, but this planetary system is a perfect case study for how exoplanets form and evolve in a star-brown dwarf binary system.
"Our discovery adds to the list of planets that can potentially be directly imaged by the next generation of telescopes," Feng said. "Ultimately, we are working toward the goal of being able to determine if planets orbiting nearby stars host life.”
"We eventually want to build a map of all of the planets orbiting the nearest stars to our own Solar System, especially those that are potentially habitable,” added Carnegie co-author Jeff Crane.
This research effort—which also included Carnegie’s Steve Shectman, John Chambers, Sharon Wang, Johanna Teske, Matías Díaz, and Ian Thompson, as well as Steve Vogt of U.C. Santa Cruz, Hugh Jones of University of Hertfordshire and Jennifer Burt of NASA’s Jet Propulsion Laboratory—culled and reanalyzed data from the European Southern Observatory’s Ultraviolet and Visual Echelle Spectrograph survey of 33 nearby red dwarf stars, which operated from 2000 to 2007 and was released in 2009.
"We have been led to this result by antique data,” joked Butler.
Once targets were discovered in the UVES archives, the researchers used observations from three planet-hunting instruments to increase the precision of the data. The Carnegie Planet Finder Spectrograph (PFS) at our Las Campanas Observatory in Chile, ESO’s High Accuracy Radial velocity Planet Searcher (HARPS) at La Silla Observatory, and the High Resolution Echelle Spectrometer (HIRES) at the Keck Observatory were all crucial to this effort.
“Combining the data from multiple telescopes increases the number of observations and the time baseline, and minimizes instrumental biases,” Butler explained.
A companion paper featuring the re-analysis of the UVES search for planets around red dwarfs was recently published in The Astronomical Journal. | 0.863014 | 3.862154 |
Is it necessary to return the status of the planet to Pluto? Scientist Philip Metzger thinks so!
A new study from the University of Central Florida suggests that the reason Pluto lost its planetary status cannot be considered valid. In 2006, the International Astronomical Union (IAU) established certain requirements for the status of the planet. One of them pointed to the need to clear the orbit (for the planet to have the greatest gravitational force).
Pluto could not fulfill the requirements. Neptune affects it by its gravity, and on the orbital path of Pluto, there are frozen gases and objects from the Kuiper belt. So, the celestial body was no longer considered a planet and assigned to the group of “dwarf planets”. However, a new study from Philip Metzger insists that this standard from the MAS is not observed in the scientific literature.
Metzger studied scientific treatises over the past 200 years and found only one publication for the year 1802, which uses the criterion of cleaning by the object of the orbit. He said that the satellites Titan and Europe have been regularly called planets since the time of Galileo. It turns out that nobody simply uses the definition of MAS in research. He also insists that this is a vague requirement, since there is not a single planet that would completely clear the orbit. The scientist added that the separation between the planets and other celestial bodies, such as asteroids, was carried out in the early 1950s. Then Gerard Kuiper published an article in which he pointed out the difference based on the process of formation.
Scientist Philip Metzger questions the logic of Pluto’s classification. He is supported by many other scientific authors
Research co-author Kirby Runyon of the Johns Hopkins Laboratory of Applied Physics says that the definition of the MAS should be considered erroneous. The study of the literature showed that the purification of the orbit is not a standard that is used to separate asteroids from the planets, as stated by representatives of the IAA in 2006. Runyon believes that the definition of a planetary nature should be based on the internal properties of the object, and not those that can change, like orbital dynamics.
Metzger proposes to classify the planet on the basis of its sufficient size: then there is a powerful gravity, which allows to achieve a spherical shape. Pluto has an underground ocean, a multi-layered atmosphere, organic compounds, evidence of ancient lakes and several satellites. It is even more dynamic and “alive” than Mars. Therefore, it would be foolish to disregard it and deny its planetary status. | 0.880161 | 3.033894 |
Scotland’s Sky in February, 2014
London students spot nearby bright supernova
One of the brightest and closest supernovae since 1987 was discovered by a student group from University College London at an observatory in north London on 21 January. Meanwhile, Jupiter is unmistakable in the best evening sky of the year and both Mars and Venus are conspicuous before dawn.
The supernova, the catastrophic disintegration of a white dwarf star, is located in the galaxy M82, some 11.5 million light years away in the constellation of Ursa Major. At its brightest, perhaps as February begins, it may be shining at about magnitude 10.0. This is too dim to target through binoculars, unless you use large ones under a perfect sky, but it is easily seen through most amateur-owned telescopes provided we know just where to look.
At the star map times, M82 and its sister galaxy M81 are located 8° above the star Lambda high in the north-east at the end of the winding constellation of Draco. M81 lies 0.6° south (right) of M82 and is larger and brighter at about the seventh magnitude. M82 is the more interesting of the two because it appears to be a spiral galaxy in the throes of unusually rapid star formation – indeed it is classed as a starburst galaxy. Perhaps triggered by a close encounter with its neighbour, the episode means that M82 has a surfeit of luminous young stars and star clusters and, consequently, may host more than its share of supernovae.
We may now expect the current supernova, dubbed SN 2014J, to dwindle to obscurity over the coming months. Eventually, though, its debris may add another twist to the complex network of dusty filaments that do their best to hide M82’s spiral structure. It is interesting to note that all four of the brightest supernovae since 1993 have occurred in different galaxies in Ursa Major.
Jupiter stood at opposition on 5 January and is conspicuous as it climbs from the east at nightfall to stand high on the meridian at our star map times. Meanwhile the glorious shape of Orion the Hunter marches from the south-east to the south-south-west, followed by Sirius which lies 40° almost due south of Jupiter and is less than half as bright. Orion’s Belt points upwards to Aldebaran and the iconic Pleiades cluster and, as Orion stands at his highest in the south, look almost overhead for the bright star Capella in Auriga.
Besides the Pleiades, three other open star clusters are plotted on our southern star map. Praesepe, or the Beehive cluster, in Cancer is the brightest of these and best seen through binoculars. Look also for M35 near the feet of Gemini, and currently 10° to the west of Jupiter, and the slightly brighter M41 4° due south of Sirius.
There is still a chance to spot Mercury as it nears the end of its best evening show in 2014. Forty minutes after sunset on the 1st it stands almost 9° high in the south-west and 7° below the slender young Moon. Use binoculars to find it at magnitude -0.4, although it may become a naked-eye object before it sets in the west-south-west another 70 minutes later. By the 8th, though, the small innermost planet is 2.5° lower and one fifth as bright at magnitude 1.4 as it disappears into the twilight on its way to inferior conjunction on the near side of the Sun on the 15th.
Sunrise/set times for Edinburgh change from 08:07/16:46 on the 1st to 07:07/17:44 on the 28th. The Moon is at first quarter on the 6th, full on the 14th and at last quarter on the 22nd. It was new on 30 January and as it emerges in our south-western sky in early February, expect earthshine (“the Old Moon in the Young Moon’s Arms”) to be impressive. It is caused, of course, by the night side of the Moon’s disk being illuminated by the almost-full Earth in the lunar sky. The phenomenon will have disappeared before the Moon stands 7° below the Pleiades on the 7th, close to Aldebaran on the 8th and right of Jupiter on the 10th.
Jupiter dims from magnitude -2.6 to -2.4 as it creeps westwards in Gemini and shrinks to 42 arcseconds if viewed telescopically. With its active meteorology and four bright moons, it is a favourite for amateur observers, particularly now that it is highest in the evenings. The magnitude 3.6 star Lambda Geminorum, 9° south-east of Jupiter, disappears behind the southern limb of the Moon on the 11th. As seen from Edinburgh, the occultation lasts from 19:55 until 20:51.
Mars doubles in brightness from magnitude 0.2 to -0.5 as its small ochre disk swells from 9 to 12 arcseconds this month. The Red Planet is tracking eastwards 5° to the north of Spica in Virgo, rises in the east about ninety minutes after our map times and crosses Edinburgh’s meridian at a height of 26° almost six hours later. Saturn follows Mars across our southern morning sky to pass 17° high in the south at 06:50 on the 1st and almost two hours earlier by the 28th. The Moon is near Mars and Spica on the 19th and 20th and closest to Saturn on the 21st when Saturn is magnitude 0.5 and 17 arcseconds wide, with the rings tipped at 23° and 39 arcseconds broad.
Venus, at its brilliant best at magnitude -4.6 on the 11th, rises above Edinburgh’s horizon in the east-south-east at 05:58 on the 1st and 51 minutes earlier by the 28th. Look for it low in the south-east before dawn and catch it close to the waning Moon on the 26th.
This is a slightly-revised version of Alan’s article published in The Scotsman on January 31st 2014, with thanks to the newspaper for permission to republish here.
Posted on 31/01/2014, in Uncategorized and tagged 2014, Alan Pickup, ASE, Astronomical Society of Edinburgh, Beehive, February, Jupiter, Mars, Mercury, Night Sky, Praesepe, Saturn, Scotland, SN 2014J, Supernova M82, The Scotsman, Ursa Major, Venus. Bookmark the permalink. Leave a comment. | 0.814499 | 3.701312 |
Gamma ray bursts (GRBs) are rare and only occur when extremely massive stars go supernova. The stars' strong magnetic fields channel most of the explosion's energy into two powerful plasma jets, one at each magnetic pole. The jets spray energetic particles at light speed for light-years in both directions.
On Earth, we detect the debris as gamma rays. Researchers also suspect - but haven't been able to prove - that GRBs are the source of at least some of the cosmic rays and neutrinos that pepper our planet from space.
Now, physicists at Ohio State University are using computer simulations to prove that theory. Their findings appear online in the journal Nature Communications. The study also raises new questions that can be answered only by the next generation of neutrino telescopes.
Mauricio Bustamante, a Fellow of the Center for Cosmology and AstroParticle Physics at Ohio State, explained that the new computer model is a result of recent findings in astroparticle physics, such as the first confirmed cosmic neutrinos detected at the IceCube Neutrino Observatory at the South Pole in 2013.
"Previously, the details of the non-uniformity of the GRB jets were not too important in our models, and that was a totally valid assumption - up until IceCube saw the first cosmic neutrinos a couple of years ago," Bustamante said, according to the press release. "Now that we have seen them, we can start excluding some of our initial predictions, and we decided to go one step further and do this more complex analysis."
With Philipp Baerwald and Kohta Murase of the Institute for Gravitation and the Cosmos at Pennsylvania State University and Walter Winter from the DESY national research center in Germany, Bustamante wrote new computer code to take into account the shock waves that are likely to occur within the jets. They simulated what would happen when blobs of plasma in the jets collided, and calculated the particle production in each region.
Bustamante explains in an analogy where the plasma jet is a long highway. "Everywhere on the highway there are fast-moving cars, but some of them will be fast sports cars, while others will be extra-fast Formula 1 racers," he said, according to the press release. "They will collide all over the highway, and when they do they will create debris. The debris always contains neutrinos, cosmic rays and gamma rays, but, depending on where the collisions occurred, one of these will typically dominate the emission."
"If the cars collide close to the beginning of the highway, where the concentration of cars is higher, the debris will be mostly neutrinos," Bustamante continued, according to the press release. "As they race along the highway, the concentration of cars goes down, and so when a collision occurs halfway through the length of the highway, the debris will be mostly cosmic rays. Further down the road, the concentration is even lower, and the gamma rays that we observe at Earth are produced in the collisions at this stage."
The amount of debris that reaches Earth depends on how energetic the star is and how far away it is.
"We expect that the next generation of neutrino telescopes, such as IceCube-Gen-2, will be sensitive to this minimal flux that we're predicting," Bustamante said, according to the press release. "Then astrophysicists can use the model to refine notions of GRB internal structure and better understand the sources of cosmic particles detected on Earth."
This work was funded by NASA, the German Research Foundation and the U.S. National Science Foundation. | 0.822814 | 4.073406 |
The last twenty years have witnessed an exceptionally fast development in the field of the extra solar planets. The known exoplanets, almost 4000 to date, already show how diverse the planets in our galaxy can be. While the detection of exoplanets is an important ongoing field of activity, the characterization of their atmosphere has just begun and it is developing very rapidly. A lot can be learnt from spectroscopic observations of an exoplanet atmosphere; the molecular composition of giant exoplanet atmospheres can trace the planet's formation and evolution; the atmosphere of rocky exoplanets can host biosignature gases. However, the observations are challenging because the signal is often embedded in instrumental and telescope systematic noise.
In the ExoplANETS_A project, we will develop novel data calibration and spectral extraction tools, as well as novel retrieval tools, based on 3D models of exoplanet atmospheres, to exploit archival data from ESA Space Science archives (HST) combined with NASA Space Archives (Spitzer, Kepler) and produce a homogeneous and reliable characterization of exoplanet atmospheres....
Playlist de 10 vidéos sur les exoplanètes, ces planètes hors du système solaire. Dédié au projet de recherche européen Exoplanets-A sur l'étude des atmosphères des exoplanètes. Soutenu par l'Université Paris-Saclay, par le programme H2020 de l'Union européenne et par le CEA.
"X-ray diagramme" of the James Webb Space Telescope showing where the backplane support frame (BSF) is in relation to the whole observatory. The BSF is the backbone of the observatory, is the primary load carrying structure for launch, and holds the science instruments. Image Credit Northrop Grumman
To be seen during the Nantes Digital Week, digital arcade box with a quiz on exoplanet habitability conditions that was co-created by CM1/CM2 school children (9-10 yr old) and ExplorNova Studio. Credit ExplorNova Studio.
Exoplanets-A has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No GA 776403.
CEA is a French government-funded technological research organisation in four main areas: low-carbon energies, defense and security, information technologies and health technologies. A prominent player in the European Research Area, it is involved in setting up collaborative projects with many partners around the world. | 0.82632 | 3.165158 |
How much can we really know about the universe beyond our galaxy? The Hubble Telescope has enabled us to see objects in space as far 13,000,000,000 light years away. But this still doesn’t give us the answers to all our questions, questions like, “What is the universe made of?” “Which elements are the most abundant?” “Does space contain undiscovered forms of matter?” “Could there be antimatter stars or galaxies?” Some of these questions cannot be answered solely from visual images, but what if we had messengers bringing us physical data from distant parts of the cosmos, beyond the reach of explorers or satellites?
In a way, we do, and these “space messengers” are called cosmic rays. Cosmic rays were first discovered in 1912 by Victor Hess when he set out to explore variations in the atmosphere’s level of radiation, which had been thought to emanate from the Earth’s crust. By taking measurements on board a flying balloon during an eclipse, Hess demonstrated both that the radiation actually increased at greater altitudes and that the sun could not be its source. The startling conclusion was that it wasn’t coming from anywhere within the Earth’s atmosphere but from outer space. Our universe is composed of many astronomical objects. BIllions of stars of all sizes, black holes, active galactic nuclei, astroids, planets and more.
During violent disturbances, such as a large star exploding into a supernova, billions of particles are emitted into space. Although they are called rays, cosmic rays consist of these high energy particles rather than the photons that make up light rays. While the light from an explosion travels in a straight line at its famous constant speed, the particles are trapped in extraordinary loops by magnetic shockwaves generated by the explosion. Crossing back and forth through these magnetic field lines accelerates them to almost the speed of light before they escape. There are lots of cosmic rays in space, and some of these particles have traveled for billions of years before reaching Earth. When they enter our atmosphere, they collide with the molecules there, generating secondary cosmic rays, lighter particles with less energy than the original.
Most of these are absorbed into the atmosphere, but some are able to reach the ground, even passing through our bodies. At sea level, this radiation is fairly low. But people who spend a lot of time at higher altitudes, such as airline crews, are exposed to much more. What makes cosmic rays useful as messengers is that they carry the traces of their origins. By studying the frequency with which different particles occur, scientists are able to determine the relative abundance of elements, such as hydrogen and helium, within the universe. But cosmic rays may provide even more fascinating information about the fabric of the universe itself. An experiment called the Alpha Magnetic Spectrometer, A.M.S., has recently been installed on board the International Space Station, containing several detectors that can separately measure a cosmic ray particle’s velocity, trajectory, radiation, mass and energy, as well as whether the particle is matter or antimatter.
While the two are normally indistinguishable, their opposite charges enable them to be detected with the help of a magnet. The Alpha Magnetic Spectrometer is currently measuring 50 million particles per day with information about each particle being sent in real time from the space station to the A.M.S. control room at CERN. Over the upcoming months and years, it’s expected to yield both amazing and useful information about antimatter, the possible existence of dark matter, and even possible ways to mitigate the effects of cosmic radiation on space travel. As we stay tuned for new discoveries, look to the sky on a clear night, and you may see the International Space Station, where the Alpha Magnetic Spectrometer receives the tiny messengers that carry cosmic secrets. | 0.857779 | 4.087621 |
Monster Star Merger Could Create Massive Mega-Star, A study of “MY Camelopardalis” binary system, published in the journal Astronomy & Astrophysics, shows that the most massive stars are made up by merging with other smaller stars, as predicted by theoretical models.
Most of the stars in our galaxy have been formed in binary or multiple systems, some of which are “eclipsing”, this is consists of two or more stars which, observed from Earth, undergo eclipses and mutual transits because of their orbital plane facing our planet. One such system is the eclipsing binary MY Camelopardalis (MY Cam). The journal Astronomy & Astrophysics has published an article on MY Cam, one of the most massive star known, with the results of observations from the Calar Alto Observatory (Almería) signed by astronomers at the University of Alicante, the Astrobiology Centre of the Spanish National Research Council (CAB-CSIC) and the Canaries’ Astrophysics Institute (IAC), along with amateur astronomers.
This article concludes that MY Cam is the most massive binary star observed and its components, two stars of spectral type O (blue, very hot and bright), 38 and 32 times the Sun’s mass, are still on the main sequence and are very close to each other, with an orbital period of less than 1.2 days, in other words, the shortest orbital period in this type of stars. This indicates that the binary was virtually formed as it is now: the stars were almost in contact at the time they were formed.
The expected development is the merger of both components into a single object over 60 solar masses before any of them have time to evolve significantly. Hence, these results demonstrate the viability of some theoretical models suggesting that most massive stars are formed by merging less massive stars.
Massive binary systems
Stars which, like the Sun, move alone in the Galaxy by trailing only their planetary system are a minority. Most stars spend their lives tied by gravity to a companion star (forming what is called a binary system) or several (what was known as multiple system). As explained by Javier Lorenzo, from the University of Alicante and first author of article, in these systems all stars describe their orbits around a common centre of mass. In particular, the stars much more massive than the Sun contain an equivalent mass to many suns and tend to always appear in company. Recent studies suggest that these high-mass stars, that are much larger and hotter than the Sun, form part of systems with at least one other companion of comparable mass.
A particularly striking example is the binary system known as MY Camelopardalis (MY Cam), in the constellation of the Giraffe. This object is the brightest star in the open cluster “Alicante 1”, which was recently identified as a small stellar nursery by researchers at the University of Alicante. Although it has been known for over fifty years that MY Cam is a high-mass star, it was only ten years ago that it was recognised as an eclipsing binary, a system in which one star passes in front of the other every time they complete their orbit, leading to changes in the brightness of the system that we perceive from Earth. This property of eclipsing binaries allows us to know many of the characteristics of the component stars through a careful study of the light that comes from them and the simple application of Newton’s law of universal gravitation.
For the study of MY Cam, professional astrophysicists obtained a large number of spectra of the system with FOCES spectrograph, which operated for many years in the 2.2 m telescope of Calar Alto Observatory. Using the Doppler Effect, these spectra allow us to measure the velocities with which the stars move in their orbits. Also, astrophysicists can determine the fundamental properties of stars, as their surface temperature and its size through a comprehensive analysis of the characteristics of the spectra. To complete the work, they had the help of amateur astronomers who measured the changes in the amount of light coming from the system along the orbit, what astrophysicists call the light curve of the system. Analysis of these data has shown that MY Cam is a truly exceptional system.
The light curve- as explained by Sergio Simon, IAC researcher and one of the authors of the article – shows that the orbital period of the system is only 1.2 days. Given the large size of the stars, they have to be extremely close to be able to do a full turn so quickly. The stars are moving at a speed of over one million km/h, but being so close, the tidal forces between them make them rotate about themselves with the same period, ie, each star turns on itself in just over a day, while the Sun, which is much smaller, turns on itself once every 26 days. Stars are like giant spinning tops and every point of the surface moves with a speed of over one million km/h. Each has a radius around 700 times bigger than the Earth’s, but turns on itself at about the same time.
But also, the stars are extremely massive. Their masses are 38 and 32 times the Sun’s mass. Such huge stars do not fit so easily into such a small orbit and the conclusion of the study is that they are actually in touch and the material of their outer layers is mixing, giving place to a common envelope (what is known as a contact binary). MY Cam is one of the most massive contact binaries known and by far the most massive whose components are so young they have not yet begun to evolve.
As stated by Ignacio Negueruela, another author from the University of Alicante, this is the most interesting aspect of MY Cam since its foreseeable future confirms some of the current theories of formation of extremely massive stars. The properties of the two components of MY Cam suggest that they are extremely young stars formed in the past two million years. This extreme youth allows us to suspect that the system was formed essentially as it is now, although perhaps the two stars were not touching initially. As they get older, their natural evolution is to become larger. Given that they have no clearance between them, this process will lead to the merger of the two stars in a single object, a real star mastodon. The details of the merger process are not known, because it has never been seen before. Some theoretical models suggest that the merger process is extremely fast, releasing a huge amount of energy in a kind of explosion. Other studies favour a less violent process, but in any event spectacular. Anyway, many astrophysicists believe that the merger of the components of a close binary is probably the most effective way to generate extremely massive stars. MY Cam is the first example of a system that can lead to one of these objects. | 0.910343 | 3.926827 |
The mighty solar system a minute dimension in the galaxy we harbour…
The mighty Sun boasts as the orthodox attraction of the solar system we harbour. Orbiting the Sun is Mercury, Venus, Earth, Mars, The Kuiper Belt Which harbours an unquestionably destinct plethora of debris, these deposits are situated between Mars and the Jovian planets. A tag allocated for the larger planets outside the kuiper belt, that are gaseous in nature instead of the rocky surfaces acknowledged in the four earth like planets within the kuiper belt. The jovian planets are Jupiter, Saturn, Uranus and Neptune. The Kuiper belt is made of asteroids, rocks and metorites which are very large and dense rocky formation! Pluto which orbits upon the Kuiper belt is acknowledged as a dwarf planet, because of such relatively small dimensions in comparison to it’s larger neighbours in the solar system. The Kuiper belt is a large ring which orbits with alignment of the solar system. Multiple dwarf like planets waltz along the belt, Eris, Haumea, Makemake, Cerus… These large rocks are rocky dwarfs or astoroids which have been rounded by orbiting the solar system.
If you can imagine a vortex of extreme heat in the centre of a ring, with objects spinning and orbiting that ring, akin to meat on a skewer being prepared for a kebab feast. The rough edges are smoothed off and melted by the intensity of the heat source.
There exist a strange hypothesis for the Kuiper belt which rings closer to a legend. The Kuiper ring itself, has a strong possibility of actually existing as the remains of an exploded/imploded planet. Either the destruction occurred via intense chemical misuses of the resources of such a mysteries planet or otherwise, war was a constant in the quadrant. The planet for this auspicious hypothesis is intriguingly known as “Krypton”
The Kuiper belt which holds the remnants of planet Krypton is amassed with metal debris. Probably the sole attention Krypton was assigned title for this mystery planet. The metal extremely dense and dark in hue, orbits within the belt! Remnants of this metal have found their journey to earth. Some segments dating back approximately 65 million years in age!
I am in agreement with such a natural hypothesis, it appears clear to myself, that this is the sole reason the kuipler belt even exist. Yet the event is not so easily acknowledged. Something of possible science fiction to the unimaginable of minds. But not impossible for a war of some form to have taken place. There appears no life on the planets in our solar system or if life had existed? I suggest it is not much different from our own. Otherwise it may have visited earth. A restriction of a particular kind exist for other life on the solar system. This I believe was born via the explosion of planet X which destroyed all life in the solar system when planet X exploded/imploded sending rays of meteor showers in every direction of the solar system. It is very probable that life existed upon every planet in the solar system until the great explosion of planet X approximately Sixty Five million years in the great age of cataclysmic events. Each planet inhabited life, evidence shows that water droplets existed in separate areas of orbiting planets.
Just for a moment… Close your eyes and imagine thus scenario:
If you can imagine quite clearly and confidently? A world war in space between at least one planet which resulted in a nuclear device so powerful which imploded the planet sending rays of meteorites to all neighborring planets in the solar system! Imagine the cataclysmic explosion of planet X, which was indeed the culprit for the emptiness we have come to acknowledge which exist in the planets which orbit our solar system. It is quite possible that the effects of the meteor shower did not render earth totally obsolete of bacteria. This might be due to the size of the meteorite which impacted earth? It is indeed quite probable that earths neighbouring planets were indeed all bombarded by far larger meteorites, which annihilated the complete biosphere and climate from the first hit… Upon each of the planets in the solar system. In other words, maybe earth just got slightly lucky in that respect regards the level one exstinction effect. The meteorite which hit earth approximately sixty five million years ago was large enough to wipe out all life but not large enough to wipe out the micro organisms, which exist below the earths surface of rocks and marsh lands!
These minute micro organisms existed underground and resurfaced to reignite life once again at a later date upon earth after the meteor strike which exhausted the dinosaurs. We could also asknowledge that possibly the life upon planet “X” was of a menacing gradient… Possibly… even, one of extraordinary development in the grandeur of machination and nonchalance, a greedy fulfillment, insatiable in appetite, possibly Psychotic in nature, perhaps unempathetic, domineering, agely juvenile, wickedly, deploymatic but chillingly evil, characteristic of aristrocratic politics, judgemental, sneaky, spying, sociopathic, hypocritical, unsympathetic or empathetic, warring, devious, uncapable of resolutions, scientific, genious, ingenuity capable of hosting weapons of mass destruction???
“Weapons of mass destruction!”
“The Weapons Of Mass Destruction!”
Here holds a candidate likeness to that of the modern day society of the western ideology and methodology here upon our earth home. If this is indeed the true case? which has already been mentioned by doctors around the world, whom have reiterated the following: “White people as a complete organism, are not from this actual planet earth” (In which we reside in). Then this realisation stands to good reason and simple logic… as the certain link to their original history and origin of life for the white homo sapients”. (Please see previous blogs regarding the origin of white homo sapient…)
The link is below (kindly view the first video at the end of the blog, spoken by a physicist of anthropologist.
From that particular blog you will indeed understand the demographics of the white homogenous history and the difficulty of natural alignment to planet earth.
Somebody or something is systematically ordering for the rearrangement of our climate for their personal interests?
This is also to the detriment of the complete diversity of native species of earth. It appears nobody else benefits but white homogenosised traits.
So if my and many others hypothesis is indeed correct, it should not be to far in our own distant future when the race of war fuelled hybrids, exact and rekindle their Renaissance with world explosions.
It appears a leap frog locust effect is on the horizon for the white homogeneous society… Who will indeed strip the entire resources of that which they come into contact with and empty the contents of whichever planet they become visitor/guest or host to…
It is also important to acknowledge maybe just maybe other societies of species in the galaxy are previleged to such information. Thus, already sustained the necessary aknowledgement of the white Psychopathic blood hunger that has stalked and savagd our planet. This fact of a superior civilisation may have well prepared for the rendezvous…
Thank you and shine a light at night!
Peace be upon friend | 0.803732 | 3.093577 |
This Hubble image shows the globular cluster Messier 69, also known as NGC 6637, which is located 29,700 light-years away in the constellation Sagittarius.
This dazzling image shows the globular cluster Messier 69, or M69 for short, as viewed through the NASA/ESA Hubble Space Telescope. Globular clusters are dense collections of old stars. In this picture, foreground stars look big and golden when set against the backdrop of the thousands of white, silvery stars that make up M69.
Another aspect of M69 lends itself to the bejeweled metaphor: As globular clusters go, M69 is one of the most metal-rich on record. In astronomy, the term “metal” has a specialized meaning: it refers to any element heavier than the two most common elements in our Universe, hydrogen and helium. The nuclear fusion that powers stars created all of the metallic elements in nature, from the calcium in our bones to the carbon in diamonds. Successive generations of stars have built up the metallic abundances we see today.
Because the stars in globular clusters are ancient, their metallic abundances are much lower than more recently formed stars, such as the Sun. Studying the makeup of stars in globular clusters like M69 has helped astronomers trace back the evolution of the cosmos.
M69 is located 29,700 light-years away in the constellation Sagittarius (the Archer). The famed French comet hunter Charles Messier added M69 to his catalog in 1780. It is also known as NGC 6637.
The image is a combination of exposures taken in visible and near-infrared light by Hubble’s Advanced Camera for Surveys, and covers a field of view of approximately 3.4 by 3.4 arcminutes. | 0.881865 | 3.31304 |
Does Mars have seasons? The answer, in a nutshell, is yes, but it’s more complicated than that.
If you could, theoretically, stand unsuited on the surface of the red planet, you might feel a different temperature at your face than at your feet, according to Michael Smith, a planetary scientist at NASA’s Goddard Space Flight Center. This is due to the thinness of Mars’ atmosphere — about 100 times thinner than Earth’s — and a lack of oceans, which on Earth help to moderate temperature. On Mars, temperatures swing wildly from one time of year to another, from day to night, and from the surface to the height of a head above it.
The planet has two different kinds of seasons that interact throughout the course of a Martian year (nearly two times longer than what we know as a year). There are the familiar winter, spring, summer and fall, caused by the planet’s tilt — 25 degrees to Earth’s 23.
But there are also two additional seasons, aphelion and perihelion, which occur because of Mars’ highly elliptical orbit. Earth’s orbit is nearly circular, meaning its distance from the sun stays largely stable. Mars’ orbit is more elongated, bringing it much closer to the sun at some times of the year than others.
Mars gets about 40 percent more energy from the sun during perihelion — when the planet is closest to the sun — than during aphelion, Smith told Weather.com. “Superimposed on the tilted-axis seasons is this other kind of season, where overall the planet is warmer when it’s near the sun and cooler when it’s far from the sun,” Smith said. “It’s interesting to watch how those two play off of each other.”
Mars’ seasons are marked by distinct weather phenomena, according to Rich Zurek, the lead Mars scientist at the Jet Propulsion Laboratory. In the winter, he explained to Weather.com, much like on Earth, heavy storms of thick cloud cover and dust move over Mars’ continents toward the equator. When Mars sweeps closest to the sun during its southern hemisphere summer, temperatures increase greatly; the extra energy is enough to launch dust storms that envelop large regions of Mars — sometimes the entire planet — for weeks or months.
Global dust storms, Smith said, tend to occur only during perihelion season and once every three or so Martian years. It’s been about three and a half since the most recent global dust storm, he added.
Despite the thin Martian air, high gusts of wind can develop year-round. The Mars Viking landers, which reached the red planet in the 1970s, measured gusts of up to 100 mph, Zurek said, enough to reshape sand dunes. Winds may get up to around 180 mph high in the atmosphere.
That said, it’s unlikely any humans will experience a Martian summer breeze on their faces anytime soon. “If you were standing on the surface you’d feel the wind flying around,” he said. “But you’d better be in a spacesuit.”
MORE FROM WEATHER.COM: What do storms look like on Mars? | 0.809106 | 3.852533 |
NASA's Wise Gets Ready to Survey the Whole Sky
WASHINGTON -- NASA's Wide-field Infrared Survey Explorer, or Wise, is chilled out, sporting a sunshade and getting ready to roll. NASA's newest spacecraft is scheduled to roll to the pad on Friday, Nov. 20, its last stop before launching into space to survey the entire sky in infrared light.
Wise is scheduled to launch no earlier than 9:09 a.m. EST on Dec. 9 from Vandenberg Air Force Base in California. It will circle Earth over the poles, scanning the entire sky one-and-a-half times in nine months. The mission will uncover hidden cosmic objects, including the coolest stars, dark asteroids and the most luminous galaxies.
"The eyes of Wise are a vast improvement over those of past infrared surveys," said Edward "Ned" Wright, the principal investigator for the mission at UCLA. "We will find millions of objects that have never been seen before."
The mission will map the entire sky at four infrared wavelengths with sensitivity hundreds to hundreds of thousands of times greater than its predecessors, cataloging hundreds of millions of objects. The data will serve as navigation charts for other missions, pointing them to the most interesting targets. NASA's Hubble and Spitzer Space Telescopes, the European Space Agency's Herschel Space Observatory, and NASA's upcoming Sofia and James Webb Space Telescope will follow up on Wise finds.
"This is an exciting time for space telescopes," said Jon Morse, NASA's Astrophysics Division director at NASA Headquarters in Washington. "Many of the telescopes will work together, each contributing different pieces to some of the most intriguing puzzles in our universe."
Visible light is just one slice of the universe's electromagnetic rainbow. Infrared light, which humans can't see, has longer wavelengths and is good for seeing objects that are cold, dusty or far away. In our solar system, Wise is expected to find hundreds of thousands of cool asteroids, including hundreds that pass relatively close to Earth's path. Wise's infrared measurements will provide better estimates of asteroid sizes and compositions -- important information for understanding more about potentially hazardous impacts on Earth.
"With infrared, we can find the dark asteroids other surveys have missed and learn about the whole population. Are they mostly big, small, fluffy or hard?" said Peter Eisenhardt, the Wise project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Wise also will find the coolest of the "failed" stars or brown dwarfs. Scientists speculate it is possible that a cool star lurks right under our noses, closer to us than our nearest known star, Proxima Centauri, which is four light-years away. If so, Wise will easily pick up its glow. The mission also will spot dusty nests of stars and swirling planet-forming disks, and may find the most luminous galaxy in the universe.
To sense the infrared glow of stars and galaxies, the Wise spacecraft cannot give off any detectable infrared light of its own. This is accomplished by chilling the telescope and detectors to ultra-cold temperatures. The coldest of Wise's detectors will operate at below 8 Kelvin, or minus 445 Fahrenheit.
"Wise is chilled out," said William Irace, the project manager at JPL. "We've finished freezing the hydrogen that fills two tanks surrounding the science instrument. We're ready to explore the universe in infrared."
JPL manages Wise for NASA's Science Mission Directorate in Washington. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp. in Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena.
More information about the Wise mission is available online at:
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Physics questionsThis is a list of recently added questions about physics.
Who in 1801 discovered the ultraviolet radiation?
Johann Wilhelm Ritter
UV radiation was discovered in 1801 when the German physicist Johann Wilhelm Ritter observed that invisible rays just beyond the violet end of the visible spectrum darkened silver chloride-soaked paper more quickly than violet light itself.
By what means can hydrocarbons easily be detected in petrophysics?
Difference in Caliper size
RHOB and NPHI values being the same
Big difference in LLS, LLD and MFSL readings
Gamma ray readings seperating
Well logs measure different physical properties of the subsurface strata. Resistivity is measured very close to the tool (MFSL), at shallow depth from the tool (LLS) and at deep depths (LLD). If there is a big difference in the resistivities it means that the deeper formation contains hydrocarbons which have very high resistivity.
Is the speed of light photons always constant?
Yes, but only in a vacuum.
No, it depends on the facility.
A speed of light is always constant.
None of the above
The speed at which light propagates through transparent materials, such as glass or air, is less than c. However, this "slowing of the light" is only due to the fact of photos being absorbed and re-emitted after a slight delay between atoms. When a photon is emitted, it's speed is always c. In exotic materials like Bose–Einstein condensates near absolute zero, the effective speed of light may be only a few metres per second.
What accidents are attributed to Sprites?
loss of communication with the satellite
computer network failures
failure of space ships
blackout of electrical networks
Sprites are large-scale electrical discharges that occur high ( 50–90 km) above cumulonimbus, giving rise to a quite varied range of visual shapes flickering in the night sky. They are usually triggered by the discharges of positive lightning between an underlying thundercloud and the ground. Sprites have been blamed for otherwise unexplained accidents involving high altitude vehicular operations above thunderstorms. Since their 1989 discovery, sprites have been imaged from the ground, from aircraft and from space, and have become the subject of intensive investigations.
What is the name of this galaxy?
The Pinwheel Galaxy ( M101) is a face-on spiral galaxy distanced 21 million light-years away from Earth in the constellation Ursa Major. M101 is a large galaxy, with a diameter of 170,000 light-years. By comparison, the Milky Way has a diameter of 258,000 light years. It has around a trillion stars, twice the number in the Milky Way. It has a disk mass on the order of 100 billion solar masses, along with a small central bulge of about 3 billion solar masses.
How many percent of the total mass of the sun is gas?
By far most of the solar system's mass is in the Sun itself: somewhere between 99.8 and 99.9 percent. The rest is split between the planets and their satellites, and the comets and asteroids and the dust and gas surrounding our star.
How much does planet Earth weigh?
about 6 billion trillion tons
about 6 million trillion tons
about 60 thousand trillion tons
nobody has calculated it exactly yet
Henry Cavendish, british physicist (1731-1810) was the first scientist to calculate mass of the Earth. Greater accuracy has not been achieved for nearly 100 years. He only made a mistake about 1% compared to today's calculations. Cavendish estimated the mass of the Earth to be 6 billion trillion tons. Modern calculations say about 5.9725 billion trillion tons. (5,97219×10^24 kg)
Where is the quietest place on earth located?
Davis Station, Antarctica
Orfield Laboratories, Minnesota
Neutrino Observatory, India
Microsoft Redmond campus, Washington,
In Building 87 on Microsoft’s Redmond campus, you’ll find an anechoic chamber—a space designed to absorb and isolate sound—built by Eckel Industries and certified by the Guinness Book of World Records as the quietest place on Earth in 2015. The chamber is so effective that the ambient level of noise inside is actually -20.6 decibels. To put that in perspective, the ambient sound level of a person in a very quiet room breathing as a resting rate is around 10 decibels.
What does the letter "M" in the famous M-theory mean?
Modern attempts to formulate M-theory are typically based on matrix theory or the AdS/CFT correspondence. According to Witten, M should stand for “magic”, “mystery”, or “membrane” according to taste, and the true meaning of the title should be decided when a more fundamental formulation of the theory is known.
What essence has complete knowledge about the Universe?
An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes. This intellect is often referred to as Laplace's demon.
Play and see more questionsPhysics quiz | 0.857059 | 3.323198 |
Hitomi, An Ambitious Endeavor Cut Short
August 19, 2016
The Hitomi X-ray Observatory, designed to study extremely energetic astrophysical processes, was launched on February 17, 2016 and lost March 26, 2016. During its shorter-than-expected life it managed to obtain and transmit significant data about the motion of gas in the Perseus galaxy cluster.1 This is quite a feat for the Hitomi Team, which consists of over 200 members.
Galaxies vs. Galaxy Clusters
Our beautiful Milky Way is a single galaxy containing between 100 and 400 billion stars, enough gas to make more stars—billions more—and ten or more times that much mass, in the form of dark matter.2 Dark matter is matter that does not absorb, emit, or reflect electromagnetic radiation and has only been detected by its gravitational effect. This is one galaxy.
A galaxy cluster contains hundreds to thousands of galaxies surrounded by superheated gas. Galaxy clusters are the largest known objects in the Universe that are held together by gravity. Scientists look to galaxy clusters to gain information on dark matter and dark energy.
What We Know About Galaxy Clusters
The superheated gas that surrounds the galaxies in a cluster moves rapidly, and is denser near the center of the galaxy cluster. Here collisions between gas particles is likely, and causes greater emitted X-ray radiation.3 NASA’s Chandra X-Ray Observatory has already learned much about the Perseus galaxy cluster, which is 250 million light years (2.366 ✕ 1024 m) from Earth. Scientists have found the existence of a black hole in its center, the formation of “bubbles” during releases of energy by the black hole that push the hot gases away, and even sound waves that are created when the bubble pushes away the surrounding gas creating a pressure wave in the gas.3
An interesting observation the Chandra X-ray Observatory made is a spike of X-ray energies shown circled in the following image of the Perseus galaxy cluster. This spike in observed X-ray energies was confirmed by other satellites and in over 70 other galaxy clusters. None of the past satellites were sensitive enough though to assure that this measured spike was not due to normal matter undergoing extreme conditions.—the Hitomi satellite had extremely sensitive equipment on it.
Center of Perseus galaxy cluster with energies measured in keV (kilo electron volts). The bright spot in the middle is a black hole. X-rays are emitted in jets as charged particles appear to spiral inward. The dark areas called “bubbles” are filled with highly energetic particles that push the gaseous material aside, creating a sound wave 57 octaves below middle C. The bubbles are created by energy released by the black hole.
Image Credit: NASA/CXC/SAO
Another question scientists have is: why don’t the large volumes of gas around the galaxies cool and form new stars? The Chandra X-ray Observatory and others have collected evidence which suggests that turbulence prevents this from happening. They observed that, as the black holes spew forth streams of energetic particles, cavities are formed in the surrounding gas (bubbles). It is believed that the gas can remain hot by energy transferred at the boundary between the cavity and the gas. As particles interact at the boundary, the motion of the particles should become turbulent and this turbulence transfers energy back to the gas, keeping it hot. The sound wave created would also transfer some energy. The two images below suggest turbulence around the galaxy clusters.
Images suggesting turbulence near dark cavities around centers of two different galaxy clusters.
Image Credit: NASA/CXC/SAO
The JAXA Hitomi X-ray Observatory
The Hitomi X-ray Observatory stood in a class of its own. It had upon it a series of instruments that together could detect a range from X-rays to gamma rays, with energies from 0.3 keV to 600 keV. Unfortunately, shortly after launch the Hitomi X-ray Observatory started spinning out of control and broke up, apparently due to centrifugal force. Before it did, however, the scientists in charge got some data. They were not done with the calibration of the instruments, but their data is good and may be the only data like it until the next X-ray observatory of such caliber (Athena) gets launched sometime in 2028.
One of the instruments on the Hitomi satellite was a soft X-ray spectrometer (SXS), which is a calorimeter cooled to near absolute zero that picks up light at energies between 0.3 keV and 12 keV. In this spectrometer, when an X-ray strikes a pixel, the pixel heats up. The device detects the amount of heating, which is directly related to the energy carried by the X-ray. This instrument imaged a portion of the Perseus Cluster for roughly 2 2/3 days (230 thousand seconds), and it did so with a resolution as good as they expected, and with 20 times better resolution than previous measurements.
What did they look at? The hot gas around the center of Perseus. Their goal was to measure the velocity of the gas and determine the turbulence as well. They did this by looking at signature spectral lines—electromagnetic energy of a certain frequency, emitted during electron transitions—from ionized iron atoms, as well as chromium, manganese, and nickel, but the strongest lines were from iron, and these were the most useful in their attempt at calibrating the spectrometer.
An iron atom at rest emits spectral lines when its outer electron goes from a higher energy level to a lower one. In this hot gas (more than 50 million ˚C) there are few outer electrons on the iron atoms: most have been removed due to the high temperatures, knocked away by collisions with other fast-moving atoms. Occasionally, one or two electrons get bound to an iron atom and fall to a lower level, emitting a specific frequency and energy of electromagnetic radiation. The ones of interest happen to be in the X-ray region. If the iron atom is moving toward the detector, that frequency and energy gets shifted to higher values, in a way proportional to the velocity of the atom. If it is moving away from the detector, it gets shifted to lower values. When a bunch of particles with a range of velocities emit the same characteristic frequency, a range of frequencies and energies are observed and a broader spectral component is measured. This is known as Doppler broadening. From the width of the broadened line a range of velocities of the emitting particles can be calculated. This shift in frequencies is like when a police car is approaching an observer standing on the side of the road, the frequency of sound produced by the car increases, but as it moves away it decreases. Watch the video below to learn more about the Doppler effect.
Hitomi, using the soft x-ray spectrometer, collected the data shown in the spectral image below. The red line is the previous best data collected by the Suzaku satellite. Hitomi’s spectrometer was 30% more sensitive.
Hitomi's soft X-ray spectrometer data. The red line is the data previously collected by the Suzaku satellite.
Image Credit: NASA's Goddard Spaceflight Center
Hitomi’s data on the core of the Perseus galaxy cluster showed a velocity dispersion of 164 ± 10 km/s (≈ 367,000 ± 22,000 mi/h). A velocity dispersion is the statistical spread of velocities about the average velocity. This is basically the velocity of the turbulence along the line of sight, and is much lower than was expected.4 Although this is a high velocity and a broad range compared to everyday speeds, it is in fact quite slow and calm for structures of such a large scale and forces as powerful as Perseus’ “bubbles”; the researchers call it “remarkably quiescent” in their report.1 They also note a change in the line of sight velocity of 150 ± 70 km/s across the 60 kiloparsecs image of Perseus’s core. The pressure of a gas is related to the speed of the gas particles, and hence its temperature. The hotter the gas, the faster the particles move, and the higher the pressure (force per unit area within the cloud). The researchers compared the pressure due to just the temperature of the cloud with what the measured velocity of turbulence would contribute and found that the pressure due to turbulence would only be about 4% that due purely to thermodynamical contributions. According to the researchers, the estimate of turbulence could be doubled by including shear forces. Still, the speed of the gas is much less than expected, the turbulence is much less than expected, and the data is generally surprising compared to previous data.
Velocity profile measured by Hitomi of the core of the galaxy cluster Perseus.
Image Credit: NASA Goddard and NASA/CXC/SAO/E. Bulbul, et al.
The research article describes different possible situations. If the observed dispersion is considered to be driven by turbulence on scales comparable with the size of the largest bubbles (about 20 to 30 kiloparsecs) then enough energy is transferred to the gas due to turbulence to prevent radiative cooling (emission of electromagnetic radiation) of the gas and halt formation of stars. This suggested scale for turbulence would also be in agreement with the inferred levels of X-ray brightness fluctuations from the surface.1 However, if the turbulence is isotropic (equal in all directions) then the energy transferred to the gas by turbulence would not be transferred far enough outward to balance the radiative cooling, and the core (which includes the hot gas) would cool and form stars at a greater rate than what is observed. Hence turbulence would need to be created throughout the core, and another mechanism would be needed to transport the energy from the bubble region to the surrounding gas of the core.1 They further note that the low level turbulence for the core region indicates it is difficult to generate and/or easy to damp.
The Hitomi team also noted that the level of turbulence they measured is enough to sustain the observed halo of radio synchrotron radiation created from ultrarelativistic electrons. Ultrarelativistic means moving very close to the speed of light in vacuum (three hundred million meters per second), and charged particles that are accelerating produce radiation.
The unfortunate, unexpected, and all too soon death of the young Hitomi observatory did not stop it from leaving a legacy. The measurements of Hitomi are excellent, the best yet, and agree with other observations, but they leave scientists with revising their ideas on how energy propagates through the core of the Perseus cluster. In Hitomi’s wake come hopes for Athena – the new observatory currently being created. Athena is scheduled to be launched in 2028.
References and Resources
1. The Hitomi collaboration, The quiescent intracluster medium in the core of the Perseus cluster, Nat. Letter 535, 7610, 117–121 (07 July 2016)
3. NASA Chandra X-Ray Observatory
4. Japan Aerospace Exploration Administration (JAXA) - HITOMI | 0.816923 | 3.964997 |
Credit: Vilppu Piirola
An international research team led by the Department of Physics and Astronomy at the University of Turku, Finland, mapped the interstellar magnetic field structure and interstellar matter distribution in the solar neighbourhood. The results of the study have been published in the esteemed European journal Astronomy & Astrophysics (A&A) in March.
Magnetic field has an important role in the processes of stellar and planetary system formation. The study led by Docent Vilppu Piirola and Docent Andrei Berdyugin is based on high-precision polarisation measurements. Starlight passing through interstellar clouds is polarised by scattering from dust particles aligned by the magnetic field.
— Polarisation means that electromagnetic oscillation is stronger in a specific direction that is perpendicular to the direction of motion of the light. The alignment of small, less than one micrometer in size, elongated dust particles is based on the same phenomenon as a compass needle aligning with the Earth’s magnetic field, although it is a more complicated process, explains Vilppu Piirola.
What makes the study particularly significant, is its connection with the results obtained from the Interstellar Boundary EXplorer (IBEX) orbiter sent to explore the interaction between the Sun and the magnetic field in the solar neighbourhood. The Sun and its magnetic field interact with the surrounding interstellar matter, and the solar wind creates a so-called local bubble where the matter density is low and only little dust exists. The task of the IBEX is to observe the interface between the Sun’s heliosphere and interstellar space and matter where the solar wind practically stops.
High-precision Equipment Reveal Magnetic Field Direction
The IBEX receives information of the interstellar magnetic field (ISMF) by observing energetic neutral atoms (e.g. neutral hydrogen) that pass through the heliospheric boundary. The ISMF direction, however, can be accurately determined only by polarisation measurements. High-precision equipment with polarisation detection sensitivity at the level of or better than 0.001 % (one part in hundred thousand) has been developed for these type of measurements at the Tuorla Observatory of the University of Turku.
Four telescopes have been used for the observations of this recently published study: two in Hawaii (Mauna Kea and Haleakala observatories), one in La Palma (Nordic Optical Telescope), and one in the southern hemisphere at the Greenhill Observatory of the University of Tasmania.
— The observations have revealed interesting magnetic filament structures both in the direction where our solar system is moving in relation to the surrounding interstellar space (heliosphere ‘nose’) and in the opposite direction (heliosphere ‘tail’). The filaments form ribbon-like arcs where dust particles and starlight polarisation have aligned with the direction of the magnetic field, says Piirola.
The results of the study have been published in the March issue of the esteemed European Astronomy & Astrophysics (A&A) journal. The article has also been selected as an A&A Highlight. The A&A Editors select particularly interesting papers as Highlights.
Docent Vilppu Piirola
Related Journal Article | 0.876117 | 4.022361 |
Galileo the Heaven Gazer
He turned a telescope up to the night sky.
He turned a telescope up to the night sky.
Galileo devoted his life to scientific, especially astronomical experiments. He was the developer, though not the 'inventor', of the telescope. In 1608 a Dutch spectacle-maker, Hans Lipperhey of Middleburg, or his assistant, had discovered that a pair of lenses could make objects, such as church steeples, look closer. At least two others, including Zacharias Janssen also claimed to have been first to make the discovery. Galileo is supposed to have heard of this discovery on his arrival in Venice in July 1609. One such perspicillum had already been demonstrated in Milan. He rushed back to Padua because he had plainly understood the commercial potential of the invention and, furthermore, he had heard that no patent had been issued. (Lipperhey applied for a Dutch government patent but it was rejected). Within a fortnight he had built a perspicillum with a convex objective lens and a smaller concave eyepiece. The device achieved a magnification power of X3. This he later improved to X10, so it is not quite true, as he later boasted, that ‘The first night after my return, I solved it’.
On the right is a print by W. F. Soare, on textured board, of Galileo in 1609 with three colleagues, testing a telescope from the Tower of St. Mark's, Venice. Adapted from a popular illustration in the 'Milestones in Optical History' series, published by Bausch & Lomb in the 1930s.
Galileo returned to Venice to demonstrate the improved model before the Doge and Ruling Council, prudently deciding to offer the instrument as a gift to the Doge. This action may have contributed to the advancement in his career that followed soon afterwards. The significance of the invention for the defence of a maritime city had not been lost on the Venetians. Whilst lots of cheap imitations followed, none was as powerful as Galileo’s perspicillum. He himself now produced a X32 device, the first model he actually called a ‘telescope’.
In April 1611 he demonstrated the telescope to the Papal Court in Rome, the success of which event may well have persuaded him to risk espousing Copernican theory. It was at this banquet that the name 'telescope' was originally coined by Prince Cesi, founder of the Accademia dei Lincei. This seems to have been at the suggestion of Giovanni Demisiani, a Greek mathematician who was elected to the Academy the following year.
Galileo was the first to both apply the telescope (X32 magnification) to astronomical observations and publish the results, revealing the mountains in the Moon, numerous stars invisible to the naked eye, the nature of the Milky Way, and four of Jupiter’s satellites (named the Medicean Stars). His finds were described in Sidereus nuncius (‘The Starry Messenger’), published in Venice, 1610, in which year he went to join his patron, the Grand Duke Cosimo, in Florence.
A significant copy of this may be found in the College library as part of another work, Pierre Gassendi's, Institutio Astronomica (to which is appended a copy of Galileo's 'Nuntius Sidereus' and Kepler's 'Dioptrice'), London, 1653. The inclusion of the Sidereus Nuncius in this edition of Gassendi's work was apparently the first printing in England of any of the works of Galileo.
Some readers dismissed the moons of Jupiter, concluding that they must be illusions brought about by the poor quality of the telescope lenses. With vapour from the eye early seventeenth century telescope lenses were prone to misting over and required constant wiping. Galileo's Venetian mistress Maria Gamba had married one Giovanni Bartoluzzi in 1610. From Bartoluzzi he obtained his supply of lens blanks made from Murano glass, which he then ground on his own lathes in his new house in Florence. In Rome in 1613 he published Istoria e dimostrazioni intorno alle macchie solari (History and Demonstrations Concerning Sunspots and their Phenomena) in which he explained the phases of Venus, the structure of Saturn, and the existence of Sun Spots. We know that he used a piece of paper on which to project images of sunspots so as to avoid retinal damage. he also interpreted comets as optical illusions but recurrent illness prevented him from observing any telescopically.
News of the telescope soon reached England. Sir Henry Wotton, ambassador to Venice under James I, wrote to the Earl of Salisbury, ‘I send herewith unto His Majesty the strangest piece of news (as I may justly call it) that he hath ever yet received from any part of the world; which is the annexed book of the Mathematical Professor at Padua, who by the help of an optical instrument…hath discovered four new planets rolling about the Sphere of Jupiter…so upon the whole subject he hath first overthrown all former astronomy…and next all astrology. By the next ship your Lordships shall receive from me one of the above instruments, as it is bettered by this man'.
Further refinements followed; for example Galileo devised a method for checking the lens curvature, thus aiding astronomic observation. All early telescopes were of the refracting type. A good example is seen in our painting of Galileo though the artist has depicted an instrument of early eighteenth century style!
The Galilean Telescope is still a recognised concept today and forms the basis of the simple spyglass. With a positive lens as the eyepiece it becomes an astronomical telescope - a somewhat different function.
Galileo constantly stressed the need for quantitative experiments and sound hypothetical reasoning, and these were matters which he discussed in Il saggiatore (Rome, 1623). His belief in the Copernican system and views about astronomy are apparent from his Dialogo sopra i due massimi sistemi del mondo (Florence, 1632), a highly technical account presented as a dialogue between a supporter of the Aristotelian-Ptolemaic tradition and an advocate of the new astronomy. Even though Galileo let the old world view win out, the new arguments were so strong that the Holy Office summoned Galileo to Rome, forced him to abjure his Copernican convictions (which it regarded as heretical), and sentenced him to confinement in his home at Arcetri and to constant supervision by the Inquisition.
In 1992, after three and a half centuries, the Vatican admitted making ‘errors’ over its handling of Galileo.
Galileo engaged with almost every branch of physics. His final, and most important work, the Discorsi e dimostrazioni matematiche intorno a due nuove scienze (Leiden, 1638) contained, among other things, the proof of the laws of the fall in vacuum, the principle of the independence of forces, and a complete theory of parabolic ballistics. This work became a cornerstone on which scientists of the next generation, including Isaac Newton, built up classical mechanics.
Galileo’s influence lasted throughout the century. His observation of Jupiter’s moons moving in and out of ‘eclipse’ was used by the Danish astronomer Ole Roemer in 1675 to estimate the speed of light (the first such attempt). This side of Galileo’s work ensured his lasting fame with a wider, educated public, far more than his important work on mechanical forces.
'The Noblest Eye is Darkened' - Galileo's blindness
Galileo’s sight began to deteriorate in the middle of 1636 when he was 68 years old, and by the end of June 1637 he had lost the use of his right eye (pictured in a detail from the museum's painting of the great man) while his left eye was affected by a constant discharge. He described seeing a 'luminous halo' around candle flames. To date there has been little speculation by modern optometrists or physicians about the possible causes of Galileo’s blindness.
In July 1636 he wrote to his friend, an Italian lawyer living in France, Elia Diodati:
I have been in bed for five weeks oppressed with weakness and other infirmities. Added to the (proh dolor!) the sight of my right eye - that eye whose labours (I have no hesitation in saying) have had such glorious results, is lost forever. That of the left, which was and is imperfect, is rendered null by a continual running.
He became totally blind early in December 1637, a few months after using the telescope to discover that the moon wobbles on its axis ('lunar libration') which was quite a remarkable observation to make with only one useful eye. At this point he wrote to Father Castelli noting that:
The noblest eye is darkened which nature ever made, an eye so privileged and so gifted with rare qualities that it may with truth be said to have seen more than the eyes of all those who are gone, and to have opened the eyes of all those who are to come.
The Pope seems to have mellowed on hearing of Galileo's severe visual impairment (and accompanying deafness) and allowed him to 'see' his friends once more, including the poet John Milton (who would later go blind himself due to glaucoma). Galileo told Diodati that, without sight, the universe had shrunk to the meagre confines of his body. From October 1638 he had a live-in companion, the 16-year old Vincenzio Viviani (1622-1703) who acted as his eyes and later wrote a gushing biography (1654). Nevertheless, despite his medical training at the University of Pisa in the 1580s neither Galileo nor his friends left behind sufficient symptomatic evidence to draw a firm diagnosis. | 0.802014 | 3.032439 |
Spartan 201 F1 [NASA]
The scientific objective of the Spartan 201 or Solar Spartan (Shuttle Pointed Autonomous Research Tool for Astronomy) mission is to probe the physics of solar-wind acceleration by observing the hydrogen, proton and electron temperatures and densities, and the solar-wind velocities in a variety of coronal structures at locations from 1.5 to 3.5 solar radii from the Sun. The instruments are an ultraviolet coronal spectrometer and a white-light coronagraph. The spectrometer measures the intensities of Lyman alpha (1215 A) and the intensities of the Oxygen VI lines (1031.9 and 1037.6 A). The white-light coronagraph measures the intensity and polarization of the electron-scattered white-light corona. Both of these instruments have been used in previous sounding rocket flights. The instruments are housed together in a cylinder that is 0.43 m in diameter and 3 m long.
The Spartan program provides a series of low-cost, free-flying space platforms to perform various scientific studies. A Spartan is launched aboard the Space Shuttle and deployed from the Orbiter, where it performs a pre-programmed mission. Scientific data are collected during each mission using a tape recorder and, in many cases, film cameras. There is no command and control capability after deployment. The Spartan is then retrieved by the Orbiter and returned to Earth for recovery of the data, refurbishment and preparation for future missions. Power during the deployed phase of the mission is provided by on-board batteries, and attitude control is accomplished with pneumatic gas jets. The onboard tape recorder provides approximately 6E9 bits of storage capacity for experiments.
This experiment was flown and retrieved five times.
|Type / Application:||UV-Ray Astronomy (Shuttle retrievable)|
|Orbit:||292 km × 298 km, 57.00° (#F1); 252 km × 265 km, 57.00° (#F2); 369 km × 382 km, 28.47° (#F3); 277 km × 283 km, 28.47° (#F4); 549 km × 560 km, 28.47° (#F5)|
|Spartan 201-F1||1993-023B||08.04.1993||CCK LC-39B||Shuttle||with Discovery F16 (STS 56)|
|Spartan 201-F2||1994-059B||09.09.1994||CCK LC-39B||Shuttle||with Discovery F19 (STS 64)|
|Spartan 201-F3||1995-048B||07.09.1995||CCK LC-39A||Shuttle||with Endeavour F9 (STS 69), WSF 2|
|Spartan 201-F4||1997-073B||19.11.1997||CCK LC-39B||Shuttle||with Columbia F24 (STS 87), AERCam Sprint|
|Spartan 201-F5||1998-064C||29.10.1998||CCK LC-39B||Shuttle||with Discovery F25 (STS 95), PANSAT| | 0.828792 | 3.006294 |
As a meteorologist on TV I was often called on to be a science generalist. From earthquakes to volcanoes to comets, I had to know enough get on the air and provide context. It was a part of the job I relished.
Comets appeared from time-to-time, allowing me to get some shaved ice and dirt and give a quick lesson. There are not many people who get the opportunity to teach science on TV. It was an honor.
What I knew would not have been enough for Comet Ison. This comet was unusual. I learned a lot.
Astronomers first caught sight of Ison in September 2012 when was 585 million miles away. Even at that distance it was bright enough to hint at big things ahead.
Automated spotting programs make comet discoveries easier. Computers look for objects that are moving while the rest of the star field stays relatively in place.
By October a paper delivered to the American Astronomical Society’s 45th Annual Division for Planetary Sciences meeting noted Comet Ison was rotating in such a way that only one side was getting heated by the Sun and it was already spurting water ice into space.
Comet Ison is/was a sungrazer. Sungrazer’s are comets which get close enough to the Sun to be intensely affected by its gravity and heat. We’d never spotted a sungrazer so far out. Probably from the Oort Cloud, this was Ison’s first trip to the rodeo.
Until Ison, all the comets I’d talked about stayed far enough away from the Sun and had ‘visited’ this part of the solar system often enough that they weren’t in peril. This one was headed inside the Roche limit.
The Roche limit, sometimes referred to as the Roche radius, is the distance within which a celestial body, held together only by its own gravity, will disintegrate due to a second celestial body’s tidal forces exceeding the first body’s gravitational self-attraction. – Wikipedia
So, if Ison was a mass of rocks, pebbles and dirt held together by ice and its own internal gravity, the Sun would probably break it apart. That’s what happened. If Ison was an asteroid or some other giant space boulder we’d probably be looking at it still. Whatever does exist today is a small fraction of its former self.
I know this now. I didn’t know this a week ago or when I was talking about much colder comets on TV.
We see comets and their signature tail because heat (usually not very much heat) allows ice to melt which in turn allows gases to vent and dust to be set free. A comet’s tail is blown by the solar wind, a field of energy blasted into space from the Sun. The tail points away from the Sun and has no relation to the direction the comet is actually moving.
If all the ice has melted and the nucleus disintegrated there’s nothing left to view. That seems to be the case. There will be no “Comet of the Century” in the December sky.
We’re very lucky it’s 2013. There are a few satellites, some far from Earth, specifically designed to monitor activity like this. They provided amazing images as Ison whipped its way around the Sun and back toward deep space.
Over the next few months, as astronomers and other specialists look at the tsunami of data produced, we’ll learn more. It’s likely we’ll find Ison’s exact makeup and what caused its demise. I wouldn’t be surprised to see some animations simulating Ison’s final interactions with the Sun.
This comet was a tease. We were told it could be the big one. Obviously, it was not.
It wasn’t a disappointment to me. My knowledge has expanded. I might have been a terrible student as a kid, but grown-up Geoff loves to learn.
Over the last few weeks I’ve heard a lot of those in the know compare comets to cats. The both have tails and they both do what they want to do. | 0.867105 | 3.410495 |
We discuss and comment on the role agriculture will play in the containment of the CO2 problem and address protocols for terraforming the planet Earth.
A model farm template is imagined as the central methodology. A broad range of timely science news and other topics of interest are commented on.
Monday, February 22, 2016
Scientists Work out how Create Matter from light, to Finally prove Einstein’s E=mc2
I do think that matter can be produced from light, although we need to understand that the photons involved have to be large enough and to have sufficient energy. Then i do not think that smashing them together is likely to be productive. I suspect that they need to be sub parallel at the least.
We have galactic jets produced by so called black holes. It is my contention that mass is consumed and is converted into light which exits the gravitational pull of the so called Black Hole. This light is all generally sub parallel accommodating a coalescence back into matter in the obvious form of hot hydrogen atoms.
This is why it is possible to have a 5000 year long jet that is not affected by gravity as would be inevitable if we were dealing with matter. In fact short range Black Hole Radiation produces a natural cloud of hot Hydrogen atoms. Thus we have a huge bright object in the center of the Galaxy.
The jet itself is formed by another natural phenomena in which a part of the surface of the Black hole temporarily subsided and converted an appreciable amount of matter into light in one huge pulse. Magnetics will control when and where and it may never repeat as a long term balance is then established.
Scientists work out how create matter from light, to finally prove Einstein’s E=mc2
Physicists in England claim they have discovered how to create matter from light, by smashing together individual massless photons– a feat that was first theorized back in 1934, and has been considered practically impossible until now. If this new discovery pans out, the final piece of the physics jigsaw puzzle that describes how light and matter interact would be complete. No one’s quite sure of the repercussions if matter can indeed be produced from photon-photon collision, but I’m sure something awesomely scientific will emerge before long.
Way back in 1930, British theoretical physicist Paul Dirac theorized that an electron and its antimatter counterpart (a positron) could be annihilated (combined) to produce two photons. Then, in 1934, two physicists — Breit and Wheeler — proposed that the opposite should also be true: That two photons could be smashed together to produce an electron and positron (a Breit-Wheeler pair). In other words, that light can be converted into matter, and vice versa — or, to phrase it another way, E=mc2 works in both directions. This would close one of the last gaps in particle physics that has been theorized, but has proven very hard to prove through observation.
Various photon-mass reactions, theorized and proven over the years
The reason it’s proven hard to observe is that photons, a lot like neutrinos or electrons, are incredibly small. Furthermore, photons are massless. These two factors make it very, very hard to collide two photons together. Basically, the only real way of guaranteeing any collisions is to pump some beams of photons up to massive energy levels (think billions of times more energetic than normal visible light), inject them into a small space, and then hope that a few Breit-Wheeler pairs are created.
That is essentially the crux of this new discovery: Steven Rose and Oliver Pike of Imperial College London have come up with a way of getting the photons up to the necessary energy levels to guarantee some collisions. They propose the use of a high-powered laser, which would then slam into a slab of gold, producing a high-intensity gamma ray (photons). Then, further down the line you would have a gold hohlraum (literally hollow space), also excited by a laser to produce a big, fat field of photons. You then smash the gamma ray into the hohlraum (pictured at the top of the story) and, according to Rose and Pike, you get some electrons and positrons flying out the other end. Voila: Proof that Breit and Wheeler knew what they were talking about. [doi:10.1038/nphoton.2014.95 – “A photon–photon collider in a vacuum hohlraum”]
What a gamma ray burst might look like
In nature, photon-photon collisions are thought to occur during gamma-ray bursts (GRBs). GRBs are the most violent explosions that our universe can produce — that we’ve discovered, anyway — and they occur vary rarely, usually during a super or hypernova. A nearby GRB would probably wipe out most of the life on Earth. Perhaps more importantly, though, it’s believed that the Big Bang itself — during the first 100 seconds or so of the creation of the universe — would’ve also played host to these photon-photon collisions. We desperately want to find out more about the universe’s first few seconds, and recreating some of those primordial processes here on Earth is one of the best ways of doing just that.
For now, this discovery is purely theoretical — but Rose and Pike say that there are plenty of laboratories around the world that have the equipment to perform photon-photon collisions. High-power lasers are ten a penny nowadays, and hohlraums are usually used in fusion experiments. “The race to carry out and complete the experiment is on,” Pike says. | 0.80709 | 3.311626 |
The standard planetary formation models assume that primitive materials, such as carbonaceous chondrites, are the precursor materials of evolved planetesimals. Past chronological studies have revealed that planetesimals of several hundred kilometers in size, such as the Howardite-Eucrite-Diogenite (HED) parent body (Vesta) and angrite parent body, began their differentiation as early as ∼3 million years of the solar system formation, and continued for at least several million years. However, the timescale of planetesimal formation in distinct regions of the inner solar system, as well as the isotopic characteristics of the reservoirs from which they evolved, remains unclear. Here we present the first report for the precise 53Mn-53Cr ages of monomict ureilites. Chemically separated phases from one monomict ureilite (NWA 766) yielded the Mn-Cr age of 4564.60 ± 0.67 Ma, identical within error to the oldest age preserved in other achondrites, such as angrites and eucrites. The 54Cr isotopic data for this and seven additional bulk ureilites show homogeneous ε54Cr of ∼-0.9, a value distinct from other achondrites and chondrites. Using the ε54Cr signatures of Earth, Mars, and Vesta (HED), we noticed a linear decrease in the ε54Cr value with the heliocentric distance in the inner region of the solar system. If this trend can be extrapolated into the outer asteroid belt, the ε54Cr signatures of monomict ureilites will place the position of the ureilite parent body at ∼2.8 AU. These observations imply that the differentiation of achondrite parent bodies began nearly simultaneously at ∼4565 Ma in different regions of the inner solar system. The distinct ε54Cr value between ureilite and carbonaceous chondrite also implies that a genetic link commonly proposed between the two is unlikely.
- Meteorites, meteors, meteoroids
- Minor planets, asteroids: general
- Nuclear reactions, nucleosynthesis, abundances
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science | 0.870426 | 3.94991 |
Hi There! Today I will present you a paper by Matthew Holman and Matthew Payne, entitled Observational constraints on Planet Nine: Astrometry of Pluto and other Trans-Neptunian Objects, which aims to derive constraints on the hypothetical Planet Nine from the orbits of small bodies, which orbit beyond the orbit of Neptune. For that, the authors investigate how an unknown, distant and massive planet, could improve the ephemerides of the known Trans-Neptunian Objects (TNOs). This study has recently been accepted for publication in The Astronomical Journal.
The quest for Planet Nine
Here is a longstanding pending question: is there a ninth planet on the Solar System? Some will answer: Yes, and its name is Pluto. But as you may know, Pluto has been reclassified in 2006 as a dwarf planet by the International Astronomical Union. So, is there another ninth planet, still to be discovered? In January 2016, Konstantin Batygin and Michael Brown, answered “probably yes” to this question, from the orbits of TNOs. They discovered that the clustering of their orbits could hardly be due to chance, and so there should be a cause, which has a gravity action. Since this study, several groups try to constrain its orbit and mass, while observers try to detect it.
The purpose of this post is to discuss the study of one of these groups. Let me briefly cite other ones (sorry for oblivion):
- In 2014, Chad Trujillo and Scott Sheppard discovered a TNO, 2012VP113, whose apparent orbit seemed to be too difficult to explain with the known planets only. This made a case for the existence of the Planet Nine.
- In 2015, a team led by the Brazilian astronomer Rodney Gomes, showed that a Planet Nine could explain an excess of bright object in the population of the most distant TNOs.
- In January 2016, Batygin and Brown published their result, which triggered a bunch of other studies.
- Hervé Beust, from Grenoble (France), showed from a statistical analysis that resonant effects with Neptune could explain the observed clustering,
- Renu Malhotra, Kat Volk and Xianyu Wang, from the University of Arizona, considered that the largest TNOs could be in mean-motion resonance with the Planet Nine, i.e. that their orbital periods could be commensurate with the one of the Planet Nine. Such a configuration has a dynamical implication on the stability of these bodies. In such a case, the TNO Sedna would be in a 3:2 resonance with the Planet Nine.
- A team led by Agnès Fienga, from the Observatoire de la Côte d’Azur (France), has suggested that a signature of the Planet Nine could be found in the deviation of the Cassini spacecraft, which currently orbits Saturn. The JPL (Jet Propulsion Laboratory, NASA) does not seem to believe in this option, and indicates that the spacecraft does not present any anomaly in its motion.
- Gongjie Li and Fred Adams, based respectively at the Harvard-Smithsonian Center for Astrophysics, and at the University of Michigan, show that the orbit of the Planet Nine is pretty unlikely to be stable, because of passing stars close to the outer Solar System, which should have ejected it.
- de la Fuente Marcos and de la Fuente Marcos, from Spain, reexamined the statistics, and concluded that there should be at least two massive perturbers beyond the orbit of Pluto
- Matthew Holman and Matthew Payne, from the Harvard-Smithsonian Center for Astrophysics, tried to constrain the orbit of the Planet Nine from the orbits of the TNOs.
All this should result in the present architecture for the Solar System (AU stand for Astronomical Unit, i.e. ≈150 million km:
- 1 AU: the Earth,
- 5.2 AU: Jupiter,
- 9.55 AU: Saturn,
- 19.2 AU: Uranus,
- 30.1 AU: Neptune,
- 39.5 – 48 AU: the Kuiper Belt,
- 39.5 AU: Pluto,
- >50 AU: the scattered disk,
- 67.8 AU: Eris
- 259.3 AU: 2012VP113
- 526.2 AU: Sedna,
- 300 – 1500 AU: the Planet Nine,
- 50,000 AU: the Oort Cloud,
- 268,000 AU: Proxima Centauri, which is the closest known star beside the Sun.
The astrometry consists to measure the position of an object in the sky. Seen by a terrestrial observer, the sky is a spherical surface. You can determine two angles which will give the direction of the object, but no distance. These two angles are the right ascension and the declination.
Determining the right ascension and the declination of an object you observe is not that easy. It involves for example to have good reference points on the sky, whose positions are accurately known, with respect to which you will position your object. These reference points are usually stars, and their positions are gathered in catalogs. You should also consider the fact that an object is more than a dot, it appears on your image as a kind of a circle. To be accurate, you should determine the location of the center of the object from its light circle, due to light diffraction. You should in particular consider the fact that the center of the light is not necessarily the center of this object.
When all this is done, you have a right ascension and a declination with uncertainties, at a given date. This date is corrected from the light travel time, i.e. the position of an object we observe was the position of the object when the Solar light was refracted on its surface, not when we observe it. Gathering several observations permits to fit ephemerides of the considered body, i.e. a theory which gives its orbit at any time. These ephemerides are very convenient to re-observe this object, and to send a spacecraft to it…
Fitting an orbit
Ephemerides give you the orbit of a given body. Basically, the orbit of a Solar System body is an ellipse, on which the body is moving. For that, a set of 6 independent orbital elements shall be defined. The following set is an example:
- the semimajor axis,
- the eccentricity (a null eccentricity means that the orbit is circular; an elliptical orbit means that the eccentricity is smaller than 1),
- the inclination, usually with respect to the ecliptic, i.e. the orbital plane of the Earth,
- the pericentre, at which the distance Sun-body is the smallest,
- the ascending node, locating the intersection between the orbital plane and the ecliptic,
- the longitude, which locates the body on its orbit.
The first 5 of these elements are constant if you have only the Sun and an asteroid; in practice they have a time dependence due to the gravitational perturbations of the other bodies, in particular the giant planets, i.e. Jupiter, Saturn, Uranus and Neptune. This study aims at identifying the gravitational influence of the Planet Nine.
A numerical simulation gives you the orbit of an asteroid perturbed by the Sun and the giant planets. But for that, you need to know initial conditions, i.e. the location of the body at a given date. The initial conditions are derived from astrometric positions. Since the astrometry does not give exact positions but positions with some uncertainty, you may have many solutions to the problem. The best fit is the solution which minimizes what we call the residuals, or the O-C, for Observed Minus Calculated. All the O-C are gathered under a statistical quantity known as χ2. The best fit minimizes the χ2.
The purpose of this study is to use 42,323 astrometric positions of TNOs with a semimajor axis larger than 30 AU, 6,677 of them involving Pluto. For that, the fitting algorithm not only includes the gravitational influence of the giant planets, but also of 10 large TNOs, and of the hypothetical Planet Nine, in considering two models: either the Planet Nine is moving on a circular orbit, or it is a fixed point-mass. Its expected orbital period, i.e. several thousands of years, is so large that no significant difference between the two models is expected, given the time span covered by the observations.
Indeed, the two models give pretty the same result. The authors split the sky into several tiles, to check the preferred locations for the Planet Nine, and it appears that for some locations the fit is better, while it is worse for some others.
They also find that if the Planet Nine has a mass of 10 Earth masses, then the distance of the Planet Nine to the Sun should be between 300 and 1,000 AU, while Batygin and Brown found it to be between 400 and 1,500 AU. This discrepancy could be explained by the presence of an another planet at a distance of 60 to 100 AU. In addition to that, the node of the Planet Nine seems to be aligned with the one of Pluto, which had already been noticed by other authors. This could reveal an enhanced dynamical interaction between them.
Finally the authors acknowledge that the astrometric positions have some inaccuracy, and that further observations could affect the results.
The quest for Planet Nine is very exciting, and I am pretty sure that new results will come in a next future!
To know more…
- The study, made freely available by the authors here, thanks to them for sharing!
- The webpage of Matthew Holman
- The profile of Matthew Payne on ResearchGate
- The press release relating the likely existence of the Planet Nine
- The study by Trujillo and Sheppard
- The study by Gomes et al.
- The study by Batygin and Brown, freely available here
- The study by Beust, also freely available here
- The study by Malhotra et al., also freely available here
- The study by Fienga et al., also freely available here
- The study by de la Fuente Marcos and de la Fuente Marcos, also freely available here
Don’t forget to leave comments! | 0.8836 | 3.830546 |
Gibbous ♎ Libra
Moon phase on 15 January 2009 Thursday is Waning Gibbous, 19 days old Moon is in Virgo.Share this page: twitter facebook linkedin
Previous main lunar phase is the Full Moon before 4 days on 11 January 2009 at 03:27.
Moon rises in the evening and sets in the morning. It is visible to the southwest and it is high in the sky after midnight.
Moon is passing about ∠24° of ♍ Virgo tropical zodiac sector.
Lunar disc appears visually 3.5% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1884" and ∠1951".
Next Full Moon is the Snow Moon of February 2009 after 25 days on 9 February 2009 at 14:49.
There is low ocean tide on this date. Sun and Moon gravitational forces are not aligned, but meet at big angle, so their combined tidal force is weak.
The Moon is 19 days old. Earth's natural satellite is moving from the middle to the last part of current synodic month. This is lunation 111 of Meeus index or 1064 from Brown series.
Length of current 111 lunation is 29 days, 19 hours and 33 minutes. This is the year's longest synodic month of 2009. It is 1 hour and 53 minutes longer than next lunation 112 length.
Length of current synodic month is 6 hours and 49 minutes longer than the mean length of synodic month, but it is still 14 minutes shorter, compared to 21st century longest.
This lunation true anomaly is ∠186.6°. At the beginning of next synodic month true anomaly will be ∠213.2°. The length of upcoming synodic months will keep decreasing since the true anomaly gets closer to the value of New Moon at point of perigee (∠0° or ∠360°).
5 days after point of perigee on 10 January 2009 at 10:52 in ♋ Cancer. The lunar orbit is getting wider, while the Moon is moving outward the Earth. It will keep this direction for the next 7 days, until it get to the point of next apogee on 23 January 2009 at 00:11 in ♑ Capricorn.
Moon is 380 382 km (236 358 mi) away from Earth on this date. Moon moves farther next 7 days until apogee, when Earth-Moon distance will reach 406 116 km (252 349 mi).
3 days after its descending node on 12 January 2009 at 08:34 in ♌ Leo, the Moon is following the southern part of its orbit for the next 11 days, until it will cross the ecliptic from South to North in ascending node on 26 January 2009 at 13:27 in ♒ Aquarius.
16 days after beginning of current draconic month in ♒ Aquarius, the Moon is moving from the second to the final part of it.
6 days after previous North standstill on 9 January 2009 at 05:38 in ♊ Gemini, when Moon has reached northern declination of ∠27.060°. Next 7 days the lunar orbit moves southward to face South declination of ∠-27.081° in the next southern standstill on 22 January 2009 at 14:02 in ♐ Sagittarius.
After 10 days on 26 January 2009 at 07:55 in ♒ Aquarius, the Moon will be in New Moon geocentric conjunction with the Sun and this alignment forms next Sun-Moon-Earth syzygy. | 0.848363 | 3.183464 |
Cherenkov Telescope Array
CTA — the World’s Largest Ground-Based Gamma-Ray Observatory
The Cherenkov Telescope Array (CTA) will be a next-generation ground-based observatory for very high energy gamma-ray astronomy. It will consist of two arrays of dishes, a southern-hemisphere array at ESO’s Paranal Observatory and a northern array on the island of La Palma, Spain. Gamma-rays are emitted by some of the hottest and most powerful objects in the Universe, such as supermassive black holes and supernovae.
CTA, with its large collecting area and wide sky coverage, will be the largest and most sensitive high-energy gamma-ray observatory in the world. The two arrays will detect gamma-rays with unprecedented accuracy and together will be 10 times more sensitive than existing instruments.
Three types of telescope are required to cover the full CTA energy range (20 gigaelectronvolts [GeV] to 300 teraelectronvolts [TeV]). Over its core energy range (100 GeV to 10 TeV), CTA will employ 40 Medium-Sized Telescopes distributed over the two array sites, accompanied by 8 Large-Sized Telescopes and 70 Small-Sized Telescopes (reaching below 100 GeV and above 10 TeV, respectively).
The current plan is that on completion, CTA will comprise 118 telescopes worldwide, with 19 dishes in the northern hemisphere and 99 dishes in the southern hemisphere. The northern hemisphere site is located at the Instituto de Astrofísica de Canarias Observatorio del Roque de los Muchachos on the island of La Palma in the Canary Islands. The southern site is located at ESO’s Paranal Observatory, around ten kilometres southeast of the Very Large Telescope. This is one of the driest and most isolated regions on Earth — an astronomical paradise. Integrating CTA into the existing Paranal–Armazones infrastructure will allow it to take advantage of ESO’s state-of-the-art facilities.
Over 1400 scientists and engineers from five continents, 31 countries and over 200 research institutes are participating in the CTA project. The majority of ESO’s Member States are represented in the CTA Consortium.
Science with CTA
The Cherenkov Telescope Array will serve as an open facility to a wide astrophysics community. Its scientific potential is extremely broad, from understanding the role of relativistic cosmic particles to the search for dark matter. Observations made with CTA will aim to understand the influence of high-energy particles in the evolution of cosmic systems, and to study some of the most extreme and violent events that occur in the high-energy Universe. CTA will probe environments from the immediate neighbourhood of black holes to the cosmic voids on the largest scales. It may even lead to brand new physics as it studies the nature of matter and forces beyond the standard model.
Although the Earth’s atmosphere prevents gamma-rays from reaching the surface, their interactions with the atmosphere create ultra-high energy particles. These particles travel faster than the speed of light in air and as a result they emit a flash of eerie blue Cherenkov radiation — similar to a sonic boom created by an aircraft exceeding the speed of sound. CTA’s mirrors and high-speed cameras will capture these short-lived flashes and pinpoint their direction. This will allow each gamma-ray to be traced back to its cosmic source, allowing astronomers to address some of the most enduring mysteries in astrophysics.
CTA will have the capability to detect gamma-rays in the energy range from a few tens of GeV up to hundreds of TeV. At the lower energies, CTA will probe transient and time-variable gamma-ray events in the distant Universe; at the higher energies it will push observational astronomy into a previously unexplored part of the electromagnetic spectrum to give a completely new view of the sky.
CTA will see the sky in higher energy resolution than ever before, allowing it to search for annihilating dark matter particles, and it will also be able to slew rapidly to catch gamma-ray bursts as they explode.
More about CTA
- Read more on the Cherenkov Telescope Array website
- Paranal Observatory First Choice to Host World’s Largest Array of Gamma-ray Telescopes
Cherenkov Telescope Array | 0.843471 | 3.657906 |
Researchers at the Instituto de Astrofísica de Canarias (IAC) and the University of Cambridge have detected lithium in a primitive star in our galaxy. The observations were made at the VLT, at the Paranal Observatory of ESO in Chile.
In astrophysics, any element heavier than hydrogen and helium is termed “metal” and lithium is among the lightest of these metals. Researchers at the IAC and the University of Cambridge have been able to detect lithium in a primitive star. This is the star J0023+0307, discovered a year ago by the same team of scientists with the Gran Telescopio Canarias (GTC) and the William Herschel Telescope (WHT) of the Observatorio del Roque de los Muchachos.
This discovery could give crucial information about the creation of atomic nuclei (“nucleosynthesis”) in the Big Bang. “This primitive star surprises us for its high lithium content, and its possible relation to the primordial lithium formed in the Big Bang,” notes David Aguado, a researcher associated with the University of Cambridge and formerly doctoral student of the IAC/ULL, who is the lead author on this article.
This star is similar to our sun, but with a much poorer metal content, less than one thousandth part of that of the solar metallicity. This composition implies that we are dealing with a star which was formed in the first 300 million years of the universe, just after the supernovae marking the final phases of the first massive stars in our galaxy. | 0.867441 | 3.667046 |
A new mystery of Titan has been uncovered by astronomers using their latest asset in the high altitude desert of Chile. Using the now fully deployed Atacama Large Millimeter Array (ALMA) telescope in Chile, astronomers moved from observing comets to Titan. A single 3 minute observation revealed organic molecules that are askew in the atmosphere of Titan. The molecules in question should be smoothly distributed across the atmosphere, but they are not.
The Cassini/Huygens spacecraft at the Saturn system has been revealing the oddities of Titan to us, with its lakes and rain clouds of methane, and an atmosphere thicker than Earth’s. But the new observations by ALMA of Titan underscore how much more can be learned about Titan and also how incredible the ALMA array is.
The ALMA astronomers called it a “brief 3 minute snapshot of Titan.” They found zones of organic molecules offset from the Titan polar regions. The molecules observed were hydrogen isocyanide (HNC) and cyanoacetylene (HC3N). It is a complete surprise to the astrochemist Martin Cordiner from NASA Goddard Space Flight Center in Greenbelt, Maryland. Cordiner is the lead author of the work published in the latest release of Astrophysical Journal Letters.
The NASA Goddard press release states, “At the highest altitudes, the gas pockets appeared to be shifted away from the poles. These off-pole locations are unexpected because the fast-moving winds in Titan’s middle atmosphere move in an east–west direction, forming zones similar to Jupiter’s bands, though much less pronounced. Within each zone, the atmospheric gases should, for the most part, be thoroughly mixed.”
When one hears there is a strange, skewed combination of organic compounds somewhere, the first thing to come to mind is life. However, the astrochemists in this study are not concluding that they found a signature of life. There are, in fact, other explanations that involve simpler forces of nature. The Sun and Saturn’s magnetic field deliver light and energized particles to Titan’s atmosphere. This energy causes the formation of complex organics in the Titan atmosphere. But how these two molecules – HNC and HC3N – came to have a skewed distribution is, as the astrochemists said, “very intriguing.” Cordiner stated, “This is an unexpected and potentially groundbreaking discovery… a fascinating new problem.”
The press release from the National Radio Astronomy Observatory states, “studying this complex chemistry may provide insights into the properties of Earth’s very early atmosphere.” Additionally, the new observations add to understanding Titan – a second data point (after Earth) for understanding organics of exo-planets, which may number in the hundreds of billions beyond our solar system within our Milky Way galaxy. Astronomers need more data points in order to sift through the many exo-planets that will be observed and harbor organic compounds. With Titan and Earth, astronomers will have points of comparison to determine what is happening on distant exo-planets, whether it’s life or not.
The report of this new and brief observation also underscores the new astronomical asset in the altitudes of Chile. ALMA represents the state of the art of millimeter and sub-millimeter astronomy. This field of astronomy holds a lot of promise. Back around 1980, at the Kitt Peak National Observatory in Arizona, alongside the great visible light telescopes, there was an oddity, a millimeter wavelength dish. That dish was the beginning of radio astronomy in the 1 – 10 millimeter wavelength range. Millimeter astronomy is only about 35 years old. These wavelengths stand at the edge of the far infrared and include many light emissions and absorptions from cold objects which often include molecules and particularly organics. The ALMA array has 10 times more resolving power than the Hubble space telescope.
The Earth’s atmosphere stands in the way of observing the Universe in these wavelengths. By no coincidence our eyes evolved to see in the visible light spectrum. It is a very narrow band, and it means that there is a great, wide world of light waves to explore with different detectors than just our eyes.
In the millimeter range of wavelengths, water, oxygen, and nitrogen are big absorbers. Some wavelengths in the millimeter range are completely absorbed. So there are windows in this range. ALMA is designed to look at those wavelengths that are accessible from the ground. The Chajnantor plateau in the Atacama desert at 5000 meters (16,400 ft) provides the driest, clearest location in the world for millimeter astronomy outside of the high altitude regions of the Antarctic.
At high altitude and over this particular desert, there is very little atmospheric water. ALMA consists of 66 12 meter (39 ft) and 7 meter (23 ft) dishes. However, it wasn’t just finding a good location that made ALMA. The 35 year history of millimeter-wavelength astronomy has been a catch up game. Detecting these wavelengths required very sensitive detectors – low noise in the electronics. The steady improvement in solid-state electronics from the late 70s to today and the development of cryostats to maintain low temperatures have made the new observations of Titan possible. These are observations that Cassini at 1000 kilometers from Titan could not do but ALMA at 1.25 billion kilometers (775 million miles) away could.
The ALMA telescope array was developed by a consortium of countries led by the United States’ National Science Foundation (NSF) and countries of the European Union though ESO (European Organisation for Astronomical Research in the Southern Hemisphere). The first concepts were proposed in 1999. Japan joined the consortium in 2001.
The prototype ALMA telescope was tested at the site of the VLA in New Mexico in 2003. That prototype now stands on Kitt Peak having replaced the original millimeter wavelength dish that started this branch of astronomy in the 1980s. The first dishes arrived in 2007 followed the next year by the huge transporters for moving each dish into place at such high altitude. The German-made transporter required a cabin with an oxygen supply so that the drivers could work in the rarefied air at 5000 meters. The transporter was featured on an episode of the program Monster Moves. By 2011, test observations were taking place, and by 2013 the first science program was undertaken. This year, the full array was in place and the second science program spawned the Titan observations. Many will follow. ALMA, which can operate 24 hours per day, will remain the most powerful instrument in its class for about 10 years when another array in Africa will come on line.
“Alma Measurements Of The Hnc And Hc3N Distributions In Titan’s Atmosphere“, M. A. Cordiner, et al., Astrophysical Journal Letters | 0.845775 | 3.973649 |
By using Gaia satellite, a team of scientists, with a little help from amateur astronomers, have found an extremely rare star system: a binary system where one star completely eclipses the other, the first of its kind ever discovered.
Supernovae are rare in occurrence, but at the center of an enigmatic nebula lie two stars that astronomers say will eventually end in a fiery, violent supernova. Astronomers believe that the two stars are set in such a tight orbit that they will merge and cause each other’s explosion and death.
Children and adults alike marvel at the rings around Saturn. In a model of our solar system, Saturn — and its rings —is typically the one that gets the most attention. But while it is easy to be fascinated by Saturn, astronomers have recently found an exoplanet with an even grander expanse of wings that is sure to wow a new generation of stargazers.
Far beyond the orbit of Neptune, trillions of comets left over from the formation of the solar system lie in wait in a region known as the Oort cloud. Here they are kept in relatively stable orbits around the sun, posing little threat to Earth save for the occasional icy rock that ventures inwards. But in the blink of a cosmic eye that could all change. | 0.920818 | 3.108384 |
Jupiter has now become the dominant object in the sky. Around the middle of the night, look for it as an extremely bright “star” high in the south off of Leo’s front end.
Binoculars can show its four brightest, so-called “Galilean,” moons. Its brightest satellite, Ganymede, might occasionally be visible to the unaided eye if you block the bright glare of Jupiter with a note card — or so I argued last week.
In fact, Ganymede is the ninth largest object in the solar system. It is larger in diameter than Mercury and is bigger than all the known dwarf planets.
All four of the Galilean moons are large enough to be considered dwarf planets in their own right if they had formed in orbit around the sun instead of in orbit around Jupiter.
Ganymede is the largest, but the other satellites are significant in their own ways.
Io, innermost of the Galilean satellites, is just a little larger than Earth’s moon. It is so close to Jupiter that it is racked by radiation and gravitational and electromagnetic influences from the planet.
As a result, Io is the most geologically active object in the solar system. The interior of the satellite is continuously stretched and pulled by the planet’s gravitation, causing violently active volcanoes to spew liquid sulfur onto its surface and into its atmosphere. That’s what gives it a bright yellow/red color as seen from passing or orbiting spacecraft.
Io is caught up in Jupiter’s intense magnetic field. The planet’s magnetosphere, as it is called, carries along the lines of magnetism enormous quantities of radiation, which are quite similar to the Van Allen radiation belts around Earth. As a result, Io is constantly bathed in, what would be for a human, deadly radiation.
In its physical construction, Europa, the second satellite out from Jupiter, is typical of all the other satellites except Io. The Galileo orbiter discovered that their cross sections are much like the solar system’s inner planets, Earth included. At the center is a metallic core surrounded by a rocky mantle.
Here the similarity ends. Europa’s crust is composed of a thin layer of water ice. Europa’s icy surface is so smooth that it has been described as looking like a billiard ball.
Because Europa is so close to Jupiter, radiated heat from the planet probably causes a layer of slush or liquid water under the solid-ice crust.
Despite its odd abundance on Earth, liquid water is a rarity in the rest of the solar system. When we finally land a probe on Europa, we will almost certainly try to bore beneath the ice and test that water.
Why? Because you, and essentially all living animals, are a bag of water, as an old “Star Trek” episode once characterized us. We carried part of the water with us as we crept out of the sea. Of all the elements that are necessary for life, water seems to top the list.
Over the years astro-biologists have checked off planet after planet in their search for the conditions of life. Perhaps a billion years ago, Mars had the necessary water to harbor some sort of simple life form, but no liquid water remains. Only Europa holds the slimmest of chances.
At almost 3,000 miles in diameter, Callisto, the outermost satellite, is almost as big as the planet Mercury.
Unfortunately, its outermost status makes it a prime target for passing meteoroids. As they are sucked into Jupiter by the planet’s enormous gravity, those tiny hunks of rock sometimes hit the most conveniently placed target. The Voyager flybys showed Callisto to be the most cratered object in the solar system. It far surpasses Earth’s moon in that respect.
Jupiter and its moons look a bit like our solar system in miniature. The moons formed out of a disc of dust and gas that girdled the planet. That disc was very much like the ring of material around the early sun that eventually coalesced into planets.
In a medium-sized telescope, if you can only see three of the four Galilean moons or if one of the four is very close to the disk of Jupiter, you may be in for one of the greatest experiences of sky watching — a transit of a moon of Jupiter across the disk of the planet.
Scan the disk of the planet carefully. If the moon isn’t passing behind the planet (you have a 50-50 chance), you’ll see a small black speck, which is the shadow of the missing moon on the surface of the clouds. The moon is lost in the glare of the planet. Its shadow will move very slowly across the Jupiter’s disk.
If the moon is just about to touch the planet, you may see both the moon and its shadow briefly before the planet’s brightness drowns out the moon’s fainter glow.
If you were floating in the clouds of Jupiter right at the spot of the moon’s shadow, you would see the sun eclipsed by that moon. But a very small sun it would be. The sun is only one-fifth the size from Jupiter as it is from Earth.
Celebration of the Sun
Luckily for us, we don’t have to go to Jupiter to see an eclipse of the sun. A partial eclipse will be visible in Central Ohio on August 21. However, looking at the sun is dangerous to your vision, so you will need to have the right equipment and some understanding of what is happening before you look.
Thus, Perkins Observatory’s Celebration of the Sun programs take on special significance this year. On July 8, 15, and 22 starting at 4 p.m., the Perkins staff and volunteers from the Columbus Astronomical Society will talk about the eclipse, the science lore, and legend of our day star, observe the sun with solar-safe telescopes, weather permitting. Please call (740) 363-1257 for details or to reserve tickets.
Tom Burns is the director of the Perkins Observatory in Delaware. | 0.864747 | 3.893315 |
First images of the Bennu asteroid sent by NASA’s OSIRIS-REx Spacecraft
The first images of the Bennu asteroid, target of the OSIRIS-REx spacecraft mission, have been shared by NASA. The craft, fully titled the “Origins Spectral Interpretation Resource Identification Security – Regolith Explorer” (OSIRIS-REx), set out on September 8 2016 and is currently around a month out from its destination. It will collect a sample from the Bennu asteroid and bring it back to Earth for scientists to study, in order to answer questions about the early solar system and to learn about both the hazards and the resources that exist in near-Earth space.
The Bennu asteroid was chosen for study for reasons both practical — because it is relatively close to the Earth and is large enough to spin slowly, making it easier to touch down on — and scientific — because the asteroid is very old, potentially even older than the solar system itself, and is well preserved. Scientists believe that it could be a kind of time capsule, showing conditions of the early solar system, and that it could even give clues about the origin of life.
Bennu is around 500m in diameter, making it a little larger than the height of the Empire State Building, and is believed to be a fragment of a catastrophic collision between two larger asteroids that occurred between 1 billion and 2 billion years ago. The asteroid is rich in carbon, which is critical for life-forming compounds on Earth, and it is thought to contain organic molecules like adenine, guanine, hypoxanthine, and more. Most importantly for the potential formation of life, there could also be water trapped in the minerals that make up the asteroid.
The OSIRIS-REx craft is on course to touch down on Bennu’s surface in July 2020, when it will collect between 60 and 2,000 grams of dirt and rocks from the asteroid, depending on the conditions there. If the probe is successful in gathering 2,000 grams of material, it would be by far the largest sample collected from a space object since the Apollo Moon landing brought back moon rocks. The sample will be packed up safely into a capsule inside the craft and will be sent back to Earth, where it should be dropped into the west desert of Utah in 2023.
The sixteen images of Bennu released this week show the OSIRIS-REx craft approaching the asteroid at the rate of one image per day, starting at 27,340 miles out from Bennu and ending at just 200 miles out.
- A Japanese spacecraft just landed two rovers on an asteroid
- Sun sets on NASA’s Dawn spacecraft after 11 years of studying asteroid belt
- Asteroid mining is almost reality. What to know about the gold rush in space
- A treasure trove of 3D scientific specimens is now free to see online
- Kepler telescope shuts down, but endows all its data to the public | 0.826292 | 3.592594 |
Stargazers can look forward to seeing several shooting stars on Tuesday night, as the Earth passes through the dust left over from Halley’s Comet.
The Eta Aquariid meteor shower is expected to peak on the night of 5 May, with up to 40 meteors per hour, and will be visible until the early morning of 6 May. This celestial display is associated with the Halley’s Comet, officially designated 1P/Halley, which orbits the Sun once every 76 years.
Tania de Sales Marques, an astronomer at the Royal Observatory Greenwich, told the PA news agency: “The last time [Halley’s Comet] was seen in the sky was 1986, and our next chance to view it will be late in the year 2061.”
Read more about garden astronomy:
Meteor showers are named after their radiant, that is, where they appear to originate from in the sky. The Eta Aquariids, for example, appear to come from the constellation of Aquarius in the southern hemisphere.
Meteoroids from Halley’s Comet strike the Earth’s atmosphere at an approximate speed of 150,000 miles per hour (240,000kph), burning up in the process.
De Sales Marques told PA: “As a comet approaches the sun it heats up, releasing gas and dust into space behind it.
“When that wake of debris intersects with the orbit of the Earth we experience meteor showers, as the particles fall towards the Earth and heat up upon entering the atmosphere, leaving bright streaks in the sky as they vaporise or break apart.”
While the Eta Aquariids is active from late April to near the end of May, Ms de Sales Marques says the best time to see it will be on the night of 5-6 May between midnight and sunrise, when the shower will be at its peak.
© PA Graphics
De Sales Marques told PA: “This is a moderately active meteor shower, with a peak rate of 40 meteors per hour, and even though its radiant [where they appear to originate from] will be below or only just above the horizon for those of us at London’s latitude, we can still look out for its meteors all across the sky.
“Our best chance will be in the hours just before dawn, facing the eastern sky.”
She advises getting far away from all artificial lights to increase the chances of catching a glimpse of the shooting stars on a moonlit night.
De Sales Marques said: “As with any other stargazing activity, the best way to see meteors is to find yourself a spot sheltered from city lights with an unobstructed view of the sky and look in the direction of the radiant.
“The Moon will be waxing gibbous throughout the night, so the sky won’t be as dark as one could hope, adding to the challenge.”
Reader Q&A: How do we predict meteor shower intensity?
Asked by: Simon Foster, Burnley
Most ‘predictions’ of the rate of meteors per hour during meteor showers are based on both theory and observation. Essentially, a computer model is built containing the trajectories of every known comet – since it is the debris from comets that forms the ‘stream’ of particles we see during a meteor shower.
This model contains information on the rate that these comets release material, along with the sizes, directions and velocities at which they are released, as well as the gravitational forces that determine their subsequent trajectories through space. The trajectory of the Earth and the conditions of the Earth’s atmosphere are also inputted into the computer model.
By watching how Earth moves through the meteor stream it is possible to estimate the likely number of meteors that will be visible during a given shower for a given location.
But different astronomers use different models. Plus, these models are partly based on difficult measurements of the meteoric particles in the Solar System, so their predictions are often only approximate.
But generally, they can be used to reliably predict when a meteor shower is likely to be more or less intense than the average. | 0.863825 | 3.315982 |
AMHERST, Mass. - In a new study reported in Nature, climate scientist Rob DeConto of the University of Massachusetts Amherst and colleagues elsewhere propose a simple new mechanism to explain the source of carbon that fed a series of extreme warming events about 55 million years ago, the Paleocene-Eocene Thermal Maximum (PETM), and a sequence of similar, smaller warming events afterward.
"The standard hypothesis has been that the source of carbon was in the ocean, in the form of frozen methane gas in ocean-floor sediments," DeConto says. "We are instead ascribing the carbon source to the continents, in polar latitudes where permafrost can store massive amounts of carbon that can be released as CO2 when the permafrost thaws."
The new view is supported by calculations estimating interactions of variables such as greenhouse gas levels, changes in the Earth's tilt and orbit, ancient distributions of vegetation, and carbon stored in rocks and in frozen soil.
While the amounts of carbon involved in the ancient soil-thaw scenarios was likely much greater than today, implications of the study appear dire for the long-term future as polar permafrost carbon deposits have begun to thaw due to burning fossil-fuels, DeConto adds. "Similar dynamics are at play today. Global warming is degrading permafrost in the north polar regions, thawing frozen organic matter, which will decay to release CO2 and methane into the atmosphere. This will only exacerbate future warming in a positive feedback loop."
He and colleagues at Yale, the University of Colorado, Penn State, the University of Urbino, Italy, and the University of Sheffield, U.K., designed an accurate model―elusive up to now―to satisfactorily account for the source, magnitude and timing of carbon release at the PETM and subsequent very warm periods, which now appear to have been triggered by changes in the Earth's orbit.
Earth's atmospheric temperature is a result of energy input from the sun minus what escapes back to space. Carbon dioxide in the atmosphere absorbs and traps heat that would otherwise return to space. The PETM was accompanied by a massive carbon input to the atmosphere, with ocean acidification, and was characterized by a global temperature rise of about 5 degrees C in a few thousand years, the researchers point out. Until now, it has been difficult to account for the massive amounts of carbon required to cause such dramatic global warming events.
To build the new model, DeConto's team used a new, high-precision geologic record from rocks in central Italy to show that the PETM and other hyperthermals occurred during periods when Earth's orbit around the sun was both highly eccentric (non-circular) and oblique (tilted). Orbit affects the amount, location and seasonality of solar radiation received on Earth, which in turn affects the seasons, particularly in polar latitudes, where permafrost and stored carbon can accumulate.
They then simulated climate-ecosystem-soil interactions, accounting for gradually rising greenhouse gases and polar temperatures plus the combined effects of changes in Earth orbit. Their results show that the magnitude and timing of the PETM and subsequent hyperthermals can be explained by the orbitally triggered decomposition of soil organic carbon in the circum-Arctic and Antarctica.
This massive carbon reservoir at the poles "had the potential to repeatedly release thousands of petagrams of carbon to the atmosphere-ocean system once a long-term warming threshold was reached just prior to the PETM," DeConto and colleagues say. Until now, Antarctica, which today is covered by kilometers of ice, has not been appreciated as an important player in such global carbon dynamics.
In the past, "Antarctica and high elevations of the circum-Arctic were suitable locations for massive carbon storage," they add. "During long-term warming, these environments eventually reached a climatic threshold," with permafrost thaw and the sudden release of stored soil carbon triggered during the Earth's highly eccentric orbits coupled with high tilt.
The model described in the paper also provides a mechanism that helps to explain relatively rapid recovery from hyperthermals associated with orbital extremes occurring about every 1.2 million years, which had until now been difficult.
Overall, they conclude, "an orbital-permafrost soil carbon mechanism provides a unifying model accounting for the salient features of the hyperthermals that other previously proposed mechanisms fail to explain." Further, if the analysis is correct and past extreme warm events can be attributed to permafrost loss, it implies that thawing of permafrost in similar environments observed today "will provide a substantial positive feedback to future warming." | 0.805429 | 3.430697 |
In this course we will study the evolution of galaxies. Fundamental astronomical processes such as star formation, recycling and enrichment of gas, formation of planets, etc. all take place in galaxies. Besides that, galaxies are the basic building blocks of the universe, and we use them to trace the evolution of the universe. This broad scope is why galaxy research is in the forefront of astronomy.
This course covers the structure of the galaxies, including dark matter, stars and gas as well as the large scale structure in which galaxies are embedded. It discusses ongoing surveys of the nearby and distant universe. A special focus will be on the evolution of galaxies. The course builds on the bachelor course Galaxies and Cosmology and assumes that the material in this course is known to the student. A very brief recapitulation will be given of the most important material.
Course work consists of exercises, a presentation, and an oral exam. The presentation is on a paper or current research project; the oral exam focuses on the discussion of a research paper.
Techniques how the mass distributions of galaxies are measured
Modeling the equilibrium of a gravitational system with a very large number of point sources
Structure of nearby and distant galaxies
Observational programs to study these galaxies
Observations that have been used to understand the evolution of galaxies
The role of dark matter in galaxy evolution and formation
Advanced models for stellar populations and their application to the study of galaxy evolution
At the end of this course, you:
Will be able to analyze recent research papers in the general area of galaxy structure and evolution, and summarize their content and list their implications
Can describe the structure and evolution of galaxies and can list the observables of galaxies underlying this knowledge
Can explain the main mechanisms responsible for galaxy formation
During this course, you will be trained to:
Plan and execute your home exercises on time
Report the solutions to your exercises clearly
Present a paper or research project
Verbally describe topics covered by this course
Mode of instruction
Homework assignments: 40% of final grade (average >= 6 as requirement to take part in paper presentations)
Paper presentation: 20% of final grade
Paper discussion + general questions: 40% of final grade
Blackboard will be used to communicate with students and to share lecture slides, homework assignments, and any extra materials. You must enroll on Blackboard before the first lecture. To have access, you need a student ULCN account.
The course is not based on any book in particular. Useful reference books concerning galaxies include:
‘Galaxy Formation and Evolution’ by Houjun Mo, Frank van den Bosch, and Simon White, ISBN13: 978-0521857932’
‘Galactic Dynamics, Princeton Series in Astrophysics’ by James Binney and Scott Tremaine, ISBN13: 978-0-691-13027-9
‘Galactic Astronomy, Princeton Series in Astrophysics’ by James Binney and Michael Merrifield, ISBN13: 978-0-691-02565-0
These books are of excellent quality and deal with a lot of material in great detail. They will be useful throughout the career of an astronomer. However, their level is generally above that of the course, and they do not discuss large scale structure or galaxy evolution in much detail. | 0.840646 | 3.546967 |
Astronomy bachelor course Radiative Processes.
Stars and planets are formed deep inside molecular clouds, but how this actually happens is still being unravelled. This course will provide a broad overview of our current theoretical and observational understanding of the physical processes involved in star- and planet formation. The course consists of two parts. First, the cloud collapse leading to protostars with dense envelopes, circumstellar accretion disks and outflows is discussed. Second, the evolution of protoplanetary disks and the scenarios for the formation of giant and terrestrial planets are presented. Kuiper Belt Objects, comets and meteorites each tell their own story about the physical processes that took place in our own early Solar System. Finally, the results are put in the context of our current knowledge of exo-planetary systems. Recent observations from the Herschel Space Observatory, ALMA and other facilities are highlighted throughout the course, as are exciting results from the Rosetta and Stardust missions to comets.
The detailed outline is:
Dense molecular clouds
Cloud collapse and spectral energy distributions
Pre-main sequence stars
High-mass star formation
Disk evolution and grain growth
Formation of planets
Chemical evolution of protostellar matter
Kuiper-Belt objects and structure of debris disks
Primitive solar system material; results from Rosetta
What do exo-planets tell us about planet formation
The student will gain up-to-date insight into one of the fastest growing research areas in astronomy. The course will provide sufficient background to be able to follow the current literature on star- and planet formation and to do research in this field or in a neighboring field (e.g., star formation in external galaxies or on cosmological scales).
In this course, students will be trained in the following behaviour-oriented skills:
Motivation (commitment, pro-active attitude, initiative)
Verbal communication (presenting, speaking, listening)
Critical thinking (asking questions, check assumptions)
Creative thinking (resourcefulness, curiosity, thinking out of the box)
Mode of instruction
Oral exam (by appointment): 100% of final grade
Presentation (optional; if chosen, both the presentation and the oral exam count for 50% for the final grade)
Blackboard is not used for this course.
Handouts of lecture notes will be made available both on paper and electronically on the course website (see below).
This course is given every other year. The next opportunity is likely Spring 2020. | 0.854277 | 3.516387 |
For many years it has been suggested that lava tubes on the Moon could provide an ideal location for a manned lunar base, by providing shelter from various natural hazards, such as cosmic radiation, meteorites, micrometeoroids, and impact crater ejecta, and also providing a natural environmental control, with a nearly constant temperature, unlike that of the lunar surface showing extreme variation in its diurnal cycle. An analysis of radiation safety issues on lunar lava tubes has been performed by considering radiation from galactic cosmic rays (GCR) and Solar Particle Events (SPE) interacting with the lunar surface, modeled as a regolith layer and rock. The chemical composition has been chosen as typical of the lunar regions where the largest number of lava tube candidates are found. Particles have been transported all through the regolith and the rock, and received particles flux and doses have been calculated. The radiation safety of lunar lava tubes environments has been demonstrated.
Journal of radiation research (ISSN 0449-3060); Volume 43 Suppl; S41-5 | 0.823362 | 3.154059 |
The Earth's oceans and the water that once flowed on Mars likely came from a similar source: meteorites that landed on the planets when they were first forming, new research suggests.
Scientists analyzed the makeup of two rare Mars rocks that crashed into Earth as meteorites, and found that Martian water probably came from planetary building blocks similar to those that formed Earth. The two planets likely formed in parallel ways, but then took divergent evolutionary paths.
This finding goes against the common idea that the water in terrestrial planets like Earth and Mars came from comets. Instead, scientists think it originated in chondritic meteorites, which contain small, granular minerals that become integrated into the planets they land on.
'These meteorites contain trapped basaltic liquids, not unlike the basalts that erupt on Hawaii," John Jones, an experimental petrologist at NASA's Johnson Space Center in Houston, said in a statement. "They are pristine samples that have sampled various Martian volatile element environments."
Jones was a co-author on a paper detailing the findings published in the journal Earth and Planetary Science Letters. The research was led by Tomohiro Usui, a former postdoctoral researcher at NASA's Lunar and Planetary Institute in Houston.
The two Martian meteorites studied represent two very different sources of ancient water from the Red Planet, the researchers found.
One space rock came from a middle layer of Mars called the mantle, with traces of water from the deep interior of the planet and about the same amount of a special type of hydrogen found on Earth. The other meteorite is enriched with material from the shallow Martian crust and atmosphere.
The meteorite from the mantle suggests Mars' interior is dry. Meanwhile, the enriched meteorite has 10 times more water, indicating the surface of Mars might have been very wet at one time.
"There are competing theories that account for the diverse compositions of Martian meteorites," Usui said. "Until this study there was no direct evidence that primitive Martian lavas contained material from the surface of Mars." | 0.83708 | 3.73322 |
Dusty star-forming galaxies (DSFGs) are found in abundance in the early universe. They are especially bright because they are experiencing a large burst of high-rate star formation. Since they are mainly at higher redshifts, we are seeing them well in the past; the high star formation rates occur typically during the early life of a galaxy.
The optical light from new and existing stars in such galaxies is heavily absorbed by interstellar dust interior to the galaxy. The dust is quite cold, normally well below 100 Kelvins. It reradiates the absorbed energy thermally at low temperatures. As a result the galaxy becomes bright in the infrared and far infrared portions of the spectrum.
Dark matter has two roles here. First of all, each dusty star-forming galaxy would have formed from a “halo” dominated by dark matter. Secondly, dark matter lenses magnify the DSFGs significantly, allowing us to observe them and get decent measurements in the first place.
An international team of 27 astronomers has observed half a dozen DSFGs at 3.6 micron and 4.5 micron infrared wavelengths with the space-borne Spitzer telescope. These objects were originally identified at far infrared wavelengths with the Herschel telescope. Combining the infrared and far infrared measurements allows the researchers to determine the galaxy stellar masses and the star formation rates.
The six DSFGs observed by the team have redshifts ranging from 1.0 to 3.3 (corresponding to look back times of roughly 8 to 12 billion years). Each of the 6 DSFGs has been magnified by “Einstein” lenses. The lensing effect is due to intervening foreground galaxies, which are also dominated by dark matter, and thus possessing sufficient gravitational fields that are able to significantly deflect and magnify the DSFG images. Each of the 6 DSFGs is therefore magnified by a lens that is mostly dark.
The lenses can result in the images of the DSFGs appearing as ring-shaped or arc-shaped. Multiple images are also possible. The magnification factors are quite large, ranging from a factor of 4 to a factor of more than 16 times. (Without dark matter’s contribution the magnification would be very much less).
It is a delicate process to subtract out the foreground galaxy, which is much brighter. The authors build a model for the foreground galaxy light profile and gravitational lensing effect in each case. They remove the light from the foreground galaxy computationally in order to reveal the residual light from the background DSFG. And they calculate the magnification factors so that they can determine the intrinsic luminosity of the DSFGs.
The stellar masses for these 6 DSFGs are found to be in the range of 80 to 400 billion solar masses, and their star formation rates are in the range of 100 to 500 solar masses per year.
One of the 6 galaxies, nicknamed HLock12, is shown in the Spitzer infrared image below, along with the foreground galaxy. The model of the foreground galaxy is subtracted out, such that in the rightmost panes, the DSFG image is more apparent. There are two rows of images, the top row shows measurements at 3.6 microns, and the bottom row is for observations at 4.5 microns.
This particular DSFG among the six was found to have a stellar mass of 300 billion solar masses and a total mass in dust of 3 billion solar masses. So the dust component is just about 1% of the stellar component. The estimated star formation rate is 500 solar masses per year, which is hundreds of times larger than the current star formation rate in our own Milky Way galaxy.
It is only because of the significant magnification through gravitational lensing (“dark lenses”) that researchers are able to obtain good measurements of these DSFGs. This lensing due to intervening dark matter allows astronomers to advance our understanding of galaxy formation and early evolution, much more quickly than would otherwise be possible.
The figure 6 is from the paper referenced below. The top row shows (a) a Hubble telescope image of the field in the near infrared at 1.1 microns, and (b) the field at 3.6 microns from the Spitzer telescope. The arc is quite visible in the Hubble image in the upper right quadrant just adjacent to the foreground galaxy in the center. The model for the foreground galaxy is in column (c) and after subtraction the background galaxy image is in column (d), along with several other faint objects. The corresponding images in the bottom row are from Spitzer observations at 4.5 microns.
B. Ma et al. 2015, “Spitzer Imaging of Strongly-lensed Herschel-selected Dusty Star Forming Galaxies” http://arxiv.org/pdf/1504.05254v3.pdf | 0.863629 | 4.179535 |
Gibbous ♊ Gemini
Moon phase on 20 January 2054 Tuesday is Waxing Gibbous, 11 days young Moon is in Gemini.Share this page: twitter facebook linkedin
Previous main lunar phase is the First Quarter before 3 days on 17 January 2054 at 02:14.
Moon rises in the afternoon and sets after midnight to early morning. It is visible to the southeast in early evening and it is up for most of the night.
Moon is passing about ∠14° of ♊ Gemini tropical zodiac sector.
Lunar disc appears visually 0.6% narrower than solar disc. Moon and Sun apparent angular diameters are ∠1939" and ∠1950".
Next Full Moon is the Wolf Moon of January 2054 after 3 days on 23 January 2054 at 20:08.
There is medium ocean tide on this date. Sun and Moon gravitational forces are not aligned, but meet at very acute angle, so their combined tidal force is moderate.
The Moon is 11 days young. Earth's natural satellite is moving from the first to the middle part of current synodic month. This is lunation 668 of Meeus index or 1621 from Brown series.
Length of current 668 lunation is 29 days, 19 hours and 40 minutes. This is the year's longest synodic month of 2054. It is 1 hour and 8 minutes longer than next lunation 669 length.
Length of current synodic month is 6 hours and 56 minutes longer than the mean length of synodic month, but it is still 7 minutes shorter, compared to 21st century longest.
This lunation true anomaly is ∠168.6°. At the beginning of next synodic month true anomaly will be ∠193.2°. The length of upcoming synodic months will keep decreasing since the true anomaly gets closer to the value of New Moon at point of perigee (∠0° or ∠360°).
10 days after point of apogee on 10 January 2054 at 05:56 in ♒ Aquarius. The lunar orbit is getting closer, while the Moon is moving inward the Earth. It will keep this direction for the next 3 days, until it get to the point of next perigee on 23 January 2054 at 19:38 in ♋ Cancer.
Moon is 369 717 km (229 731 mi) away from Earth on this date. Moon moves closer next 3 days until perigee, when Earth-Moon distance will reach 356 512 km (221 526 mi).
7 days after its descending node on 13 January 2054 at 02:36 in ♓ Pisces, the Moon is following the southern part of its orbit for the next 5 days, until it will cross the ecliptic from South to North in ascending node on 26 January 2054 at 01:32 in ♍ Virgo.
21 days after beginning of current draconic month in ♍ Virgo, the Moon is moving from the second to the final part of it.
12 days after previous South standstill on 7 January 2054 at 19:44 in ♐ Sagittarius, when Moon has reached southern declination of ∠-18.772°. Next day the lunar orbit moves northward to face North declination of ∠18.720° in the next northern standstill on 21 January 2054 at 23:45 in ♊ Gemini.
After 3 days on 23 January 2054 at 20:08 in ♋ Cancer, the Moon will be in Full Moon geocentric opposition with the Sun and this alignment forms next Sun-Earth-Moon syzygy. | 0.848363 | 3.151922 |
The Moon will pass close to the Sun and become lost in the Sun's glare for a few days.
The Moon's orbital motion carries it around the Earth once every four weeks, and as a result its phases cycle from new moon, through first quarter, full moon and last quarter, back to new moon once every 29.5 days.
This motion also means that the Moon travels more than 12° across the sky from one night to the next, causing it to rise and set nearly an hour later each day. Click here for more information about the Moon's phases.
At new moon, the Earth, Moon and Sun all lie in a roughly straight line, with the Moon in the middle, appearing in front of the Sun's glare. In this configuration, we see almost exactly the opposite half of the Moon to that which is illuminated by the Sun, making it doubly unobservable because the side we see is unilluminated.
Over coming days, the Moon will rise and set an hour later each day, becoming visible in the late afternoon and dusk sky as a waxing crescent which sets soon after the Sun. By first quarter, in a week's time, it will be visible until around midnight.
At the moment of closest approach, it will pass within 0°58'of the Sun, in the constellation Virgo. The exact positions of the Sun and Moon will be:
|Object||Right Ascension||Declination||Constellation||Angular Size|
The coordinates above are given in J2000.0.
|The sky on 02 June 2020|
11 days old
All times shown in EDT.
Never attempt to point a pair of binoculars or a telescope at an object close to the Sun. Doing so may result in immediate and permanent blindness.
The circumstances of this event were computed using the DE405 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).
This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.
|03 Oct 1986||– New Moon|
|05 Oct 1986||– The Moon at perihelion|
|07 Oct 1986||– The Moon at perigee|
|10 Oct 1986||– Moon at First Quarter| | 0.878248 | 3.636987 |
Solar System’s First Interstellar Visitor Dazzles Scientists
Astronomers recently scrambled to observe an intriguing asteroid that zipped through the solar system on a steep trajectory from interstellar space-the first confirmed object from another star.
Now, new data reveal the interstellar interloper to be a rocky, cigar-shaped object with a somewhat reddish hue. The asteroid, named ‘Oumuamua by its discoverers, is up to one-quarter mile (400 meters) long and highly-elongated-perhaps 10 times as long as it is wide. That aspect ratio is greater than that of any asteroid or comet observed in our solar system to date. While its elongated shape is quite surprising, and unlike asteroids seen in our solar system, it may provide new clues into how other solar systems formed.
The observations and analyses were funded in part by NASA and appear in the Nov. 20 issue of the journal Nature. They suggest this unusual object had been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with our star system.
“For decades we’ve theorized that such interstellar objects are out there, and now – for the first time – we have direct evidence they exist,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate in Washington. “This history-making discovery is opening a new window to study formation of solar systems beyond our own.”
Immediately after its discovery, telescopes around the world, including ESO’s Very Large Telescope in Chile, were called into action to measure the object’s orbit, brightness and color. Urgency for viewing from ground-based telescopes was vital to get the best data.
Combining the images from the FORS instrument on the ESO telescope using four different filters with those of other large telescopes, a team of astronomers led by Karen Meech of the Institute for Astronomy in Hawaii found that ‘Oumuamua varies in brightness by a factor of 10 as it spins on its axis every 7.3 hours. No known asteroid or comet from our solar system varies so widely in brightness, with such a large ratio between length and width. The most elongated objects we have seen to date are no more than three times longer than they are wide.
“This unusually big variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape,” said Meech. “We also found that it had a reddish color, similar to objects in the outer solar system, and confirmed that it is completely inert, without the faintest hint of dust around it.”
These properties suggest that ‘Oumuamua is dense, composed of rock and possibly metals, has no water or ice, and that its surface was reddened due to the effects of irradiation from cosmic rays over hundreds of millions of years.
A few large ground-based telescopes continue to track the asteroid, though it’s rapidly fading as it recedes from our planet. Two of NASA’s space telescopes (Hubble and Spitzer) are tracking the object the week of Nov. 20. As of Nov. 20, ‘Oumuamua is travelling about 85,700 miles per hour (38.3 kilometers per second) relative to the Sun. Its location is approximately 124 million miles (200 million kilometers) from Earth — the distance between Mars and Jupiter – though its outbound path is about 20 degrees above the plane of planets that orbit the Sun. The object passed Mars’s orbit around Nov. 1 and will pass Jupiter’s orbit in May of 2018. It will travel beyond Saturn’s orbit in January 2019; as it leaves our solar system, ‘Oumuamua will head for the constellation Pegasus.
Observations from large ground-based telescopes will continue until the object becomes too faint to be detected, sometime after mid-December. NASA’s Center for Near-Earth Object Studies (CNEOS) continues to take all available tracking measurements to refine the trajectory of 1I/2017 U1 as it exits our solar system.
This remarkable object was discovered Oct. 19 by the University of Hawaii’s Pan-STARRS1 telescope, funded by NASA’s Near-Earth Object Observations(NEOO) Program, which finds and tracks asteroids and comets in Earth’s neighborhood. NASA Planetary Defense Officer Lindley Johnson said, “We are fortunate that our sky survey telescope was looking in the right place at the right time to capture this historic moment. This serendipitous discovery is bonus science enabled by NASA’s efforts to find, track and characterize near-Earth objects that could potentially pose a threat to our planet.”
Preliminary orbital calculations suggest that the object came from the approximate direction of the bright star Vega, in the northern constellation of Lyra. However, it took so long for the interstellar object to make the journey – even at the speed of about 59,000 miles per hour (26.4 kilometers per second) — that Vega was not near that position when the asteroid was there about 300,000 years ago.
While originally classified as a comet, observations from ESO and elsewhere revealed no signs of cometary activity after it slingshotted past the Sun on Sept. 9 at a blistering speed of 196,000 miles per hour (87.3 kilometers per second).
The object has since been reclassified as interstellar asteroid 1I/2017 U1 by the International Astronomical Union (IAU), which is responsible for granting official names to bodies in the solar system and beyond. In addition to the technical name, the Pan-STARRS team dubbed it ‘Oumuamua (pronounced oh MOO-uh MOO-uh), which is Hawaiian for “a messenger from afar arriving first.”
Astronomers estimate that an interstellar asteroid similar to ‘Oumuamua passes through the inner solar system about once per year, but they are faint and hard to spot and have been missed until now. It is only recently that survey telescopes, such as Pan-STARRS, are powerful enough to have a chance to discover them.
“What a fascinating discovery this is!” said Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory, Pasadena, California. “It’s a strange visitor from a faraway star system, shaped like nothing we’ve ever seen in our own solar system neighborhood.” | 0.933171 | 3.856084 |
Launching the Mission:
When can vehicles be launched?
What method of propulsion will we use?
What will the launch vehicles carry?
How many launches will there be?
The orbits of Earth and Mars provide us with a 15 year trajectory cycle which is divided into 7 launch windows. Basically, about every 26 months a launch window presents itself and it is during this time that any spacecraft traveling to Mars must be launched. The Reference Mission begins with the first launch of Mars-crew support equipment in the year 2007. In each of the launch windows it is assumed that 3 successful launches are made to a common safe landing site where each mission will add to previously established infrastructure.
1) Propulsion for Inbound Mars Transit
Conventional chemical rockets (currently used for the space shuttle) will be used to launch Mars-bound spacecraft into LEO. The propulsion system that will most likely be used by the Mars transit vehicles once in LEO will be Nuclear Thermal Propulsion. Developed to near-flight status in the 1960s, for any given velocity change, a nuclear thermal rocket (NTR) uses about half as much propellant as a chemical engine. The liquid hydrogen NTR rocket will be used only after the spacecraft has left the Earth's atmosphere and adequate shielding will exist in the trans-Mars injection (TMI) stage of the transfer vehicle to protect the astronauts from radiation which will develop while the rockets are firing. The NTR will only be used on the outbound leg of the mission; the main benefit being the increased payload capability of such a rocket due to the dramatic reduction in required fuel for transit. Other theoretical and untested methods of propulsion exist, but only NTR technology is both feasible and significantly developed for use on a near-future mission.
2) Launch Schedule
The following launch schedule is intended for reference use only; none of these launches have approval or funding. Nonetheless, the sequence of launch events seen here can be applied starting in any of the 7 launch opportunities within any 15 year trajectory cycle.
A) The September 2007 Opportunity:
Launch 1 (Cargo) - A fully fueled Earth return vehicle (ERV) is delivered to Mars orbit on the minimum energy trajectory. The ERV will contain supplies for the crew on their return to Earth and it will be identical to the habitat used by the astronauts during their stay on, and their transit to, Mars. The ERV will also include an Earth re-entry capsule in which the crew will "splash down" into the ocean upon Earth return in much the same way as the astronauts of the Apollo missions.
Launch 2 (Cargo) - This launch will send mission critical equipment to the surface of Mars, also on the minimum energy trajectory. The payload will consist of an unfueled Mars ascent vehicle (MAV), a liquid oxygen/methane propellant production module, a 160 kW nuclear power module, a supply of liquid hydrogen (to be explained later), a utility truck, and a pressurized rover.
Launch 3 (Cargo) - Here a surface laboratory, a second 160 kW nuclear power module, a utility truck, tools, spare parts, and a remotely controlled rover will be delivered to the Mars surface via the minimum energy trajectory. The second nuclear power module will provide complete power system redundancy and, should it become necessary to use the laboratory module as an emergency shelter, the surface laboratory will contain non-perishable food supplies for the crew.
B) The October 2009 Opportunity:
Prior to launching further cargo missions or the crew, all surface equipment delivered during the 2007 launch window will need to be checked out. It must be confirmed that the previously delivered MAV is fully fueled and that all safety and mission critical systems check out. The ERV in Mars orbit must also be verified to be fully functional. If any of the crew safety or mission critical systems are not functioning properly, the crew launch will be postponed until those systems can be restored or replaced. System redundancy is crucial to the safety of the Mars astronauts; especially the MAV and the ERV systems.
Launch 1 (Cargo) - This launch is identical to the first launch of the 2007 opportunity. A second fully fueled ERV is delivered to Mars orbit on the minimum energy trajectory. This ERV will provide return vehicle redundancy for the first Mars crew and, if unused by the first Mars crew, this ERV will be used by the second Mars crew due to be launched in the window beginning late in 2011. Typically, the ERVs will remain untended for 4 years before they are used by a returning Mars crew.
Launch 2 (Cargo) - This launch will be similar to the second launch of the 2007 opportunity. A second unfueled MAV will be delivered along with a second liquid oxygen/methane propellant production module, more liquid hydrogen, scientific equipment, spare parts, and bioregenerative life support equipment. The second MAV provides system redundancy for the Mars crew in the event that the first MAV is somehow inoperable. The MAVs will generally be on the Mars surface for 4 years before use due to the ascent vehicle redundancy necessary to ensure the safe return of the astronauts. The bioregenerative life support equipment is not critical to mission success, but it will be a valuable experiment in life support system technology. It is hoped that a bioregenerative life support system could be used to produce small amounts of fresh food and also help to recycle air and water.
Launch 3 (First Mars Crew) - This will be the first crewed vehicle ever to make the journey to Mars. They will depart in mid-November of 2009 on the fast transit trajectory. The 2009 window is the "worst case" scenario in which the transit time to Mars will be about 180 days. By initiating the human Mars exploration program during the most difficult transit scenario, we will be well prepared for all future missions. The fast transit trajectory will put the astronauts in Mars orbit about 2 months before the arrival of the fourth and fifth cargo missions. If for some reason the astronauts are unable to land at the site of the previous cargo missions, the astronauts' transit module will contain all of the crew provisions needed for the 180 day transit as well as the 500-600 day surface stay (the arriving MAV could then be redirected to land nearby). The transit module will also serve as the main crew quarters during the astronauts' stay on Mars.
The first Mars crew will likely consist of 6 or 7 individuals who possess expertise in several disciplines. Some of the areas of knowledge that will be required by the crew will include: 1) maintenance, repair and operations of mechanical, electrical, and electronic devices 2) general medicine including surgery, psychology, and biomedicine 3) geology, geophysics, paleontology, geochemistry, and atmospheric science 4) biology, botany, ecology, and social science. In addition to these areas of expertise, all crew members will require extensive skills in management, communications, computer science, navigation, and journalism (a large part of the return on mission investment is the reporting of surface operations to the population of Earth).
C) The December 2011 Opportunity: & D) The March 2014 Opportunity:
The next two launch windows will closely mirror the 2009 launch opportunity. Each window will consist of two cargo launches followed by one crewed vehicle. The equipment carried by the cargo missions will depend upon several factors: 1) the suggestions made by the first crew 2) required spare parts 3) status of surface systems (ie. system redundancy must be maintained) 4) scientific objectives (these are likely to change as the mission proceeds).
While they will be similar to the 2009 mission, it would be impossible to predict the exact structure of the 2011 and 2014 Mars missions. Unforeseen developments on the Martian surface, as well as developments here on Earth, will certainly alter the course of human Mars exploration to some degree. One thing that is for certain is the fact that the 2011 and 2014 missions will build on the infrastructure and scientific achievements of the mission(s) before them. Over the course of the total of 12 launches from Earth, significant amounts of equipment will accumulate at the landing site and Mars surface operations experience will be continually developed. Our expanding knowledge of Mars as a planet will lead us is new directions of exploration, on Mars and on Earth, and perhaps a second Mars landing site will be selected for future investigation. The experience gained from previous Mars missions will streamline the process of "outpost" establishment significantly and advances in technology will make Mars increasingly accessible to astronauts. As old questions are answered and new ones are raised, we will be well on our way to establishing a future in which we step out into the stars in search of answers. As one can imagine, a human Mars exploration program spanning only 9 years would certainly provide significant returns.
Why Go to Mars? - motivations behind a human Mars exploration program
Mission Objectives and Profiles - objectives, risk evaluation, trajectories, travel/stay times, split mission strategy
Landing on the Martian Surface - entry & landing, surface equipment, surface operations
Surface Systems - power, return propellant production, surface life support
Return to Earth - ascent from the Mars surface, Earth Return Vehicle
Back to Mars Exploration Homepage
NSSDCA Planetary Science Homepage | 0.82809 | 3.460411 |
Aurora Borealis (07:11)
The sun emits a steady stream of charged particles known as solar wind, a cosmic force sometimes intensified by solar flares. As charged particles stream along Earth's magnetic field towards the poles, they excite gasses that produce colored lights.
Solar Energy (02:59)
Increased solar activity associated with auroras can generate about one million megawatts of electricity. This energy can disrupt power lines, electronics, and more. The auroras are good measures of solar activity.
Shooting Stars (04:18)
What is a "shooting star?" It is a piece of space debris (rocks, dust, pebbles) shooting through Earth's atmosphere. These meteors originate from the formation of the solar system.
Cosmic Rays (04:30)
Cosmic rays are particles that come from space. They emit radiation, but Earth's atmosphere protects the planet from most of them. Cosmic rays can cause DNA mutations and affect certain weather phenomena.
Transient Luminous Events (03:25)
Large thunderstorms are capable of producing electrical phenomena called transient luminous events (TLEs). The most common TLEs include red sprites, blue jets, and elves.
Key Roles of the Sun on Earth (04:06)
The sun "tells" plants when to flower, and it initiates life-giving processes of photosynthesis. Plants provide much of the food humans consume, and they give off oxygen essential for life. The sun may help animals navigate on the planet.
Earth's Magnetic Field (04:28)
When conditions obscure the sun, some animals switch to Earth's magnetic field for directional and positional cues. Homing pigeons may first use the sun to orient themselves and then switch their sense of smell and the Earth's magnetic field.
Ultraviolet Rays (04:13)
There are three classifications of ultraviolet rays. UVA is known as the aging and skin-cancer ray; UVB is considered the burning ray. People who live in the sun and have light eyes and skin are most vulnerable to UVB rays.
Sunscreen Protection (01:46)
Regular sunscreen does not protect humans from skin cancer and premature aging. SPF only measures UVB protection, but not UVA. The most effective sunscreens protect against UVB and UVA.
Rainbows form when sunlight passes through spherical droplets, bending the light as it passes through. This gives the different colors of rainbows. No two people see the exact same rainbow.
Credits: Cosmic Phenomena (00:39)
Credits: Cosmic Phenomena
For additional digital leasing and purchase options contact a media consultant at 800-257-5126
(press option 3) or [email protected]. | 0.813516 | 3.214638 |
October is designated as American Archive Month, to promote an awareness of the importance of historical records. While many think ‘archive’ may only apply to books and letters, there are other important archives. Archives are used for major telescopes and observatories, including NASA’s Chandra X-ray Observatory.
The primary role of the Chandra Data Archive (CDA) is to store and distribute data so the astronomical community, as well as the general public, have access to it. The CDA does this with the aid of powerful search engines. This archive collection will preserve the legacy of the Chandra mission for generations.
In celebration of American Archive Month, the Chandra team chose images from a group of eight objects in the CDA to be released to the public for the first time. These are but a few of the thousands of objects that Chandra’s archive has made permanently available to the public.
Chandra’s observation of this supernova remnant, located around 2,400 light years away in the constellation Vela, revealed extremely high-energy particles. These particles are produced as the shock wave from the explosion expands into interstellar space. The X-rays from Chandra (purple) have been combined with optical data from the Digitized Sky Survey (red, green, and blue).
This is a wide and double-lobed jet, generated by a supermassive black hole at the centre of a galaxy about 410 million light years away, in the constellation Ophiuchus. The jet itself is the tiny point in the centre while the giant plumes of radiation can be seen in X-rays from Chandra (purple) and radio data from the Very Large Array (orange).
This nebula is located around 9,000 light years away from Earth, in the Sagittarius arm of the Milky Way galaxy. The scattered X-ray data detected by Chandra (blue) are probably due to the winds from young, massive stars blowing throughout the nebula. Optical data from ESO are shown in orange and yellow.
This galaxy is similar in appearance to our own, but contains a much more active supermassive black hole within the white area near the top. NGC 4945 is only about 13 million light years from Earth, in the constellation Centaurus, and is seen edge-on. X-rays from Chandra (blue), have been overlaid on an optical image from the European Space Observatory to reveal the presence of the supermassive black hole at the centre of this galaxy.
The nebula otherwise known as the Elephant Trunk Nebula is located about 2,800 light years away in the constellation of Cepheus. Radiation and winds from massive young stars seem to be triggering new generations of stars to form. X-rays from Chandra (purple) have been combined with optical (red, green, and blue) and infrared (orange and cyan) to give a more complete picture of this source.
3C 397 (G41.1-0.3)
Also known as G41.1-0.3, this is a Galactic supernova remnant with an unusual shape found around 33,000 light years away in the constellation Aquila. Its box-like shape is possibly produced as the heated remains of the exploded star interacts with the cooler gas enveloping it. The exploded star was detected by Chandra in X-rays (purple) and this composite of the area around 3C 397 also contains infrared emission from Spitzer (yellow) and optical data from the Digitized Sky Survey (red, green, and blue).
This supernova is located approximately about 180,000 light years away in the constellation Tucana, within our neighbouring galaxy of the Small Magellanic Cloud. Observations of the dynamics as well as the composition of the debris from the explosion provide evidence that the explosion was produced by the collapse of the central core of a star. In this image, X-rays from Chandra (purple) are combined with infrared data from the 2MASS survey (red, green, and blue).
Nicknamed the ‘Fireworks Galaxy’, this medium-sized, face-on spiral galaxy is found about 22 million light years away from Earth in the constellation Cygnus. Eight supernovae have been observed to explode in the arms of this galaxy in the last 100 years. Chandra observations (purple) have revealed three of the oldest supernovas ever detected in X-rays. This composite image also includes optical data from the Gemini Observatory in red, yellow, and cyan. | 0.845559 | 3.742681 |
Hubble captures stunning image of galaxies colliding
NASA's venerated Hubble Space Telescope has captured a striking image of the larger galaxy NGC 7714 colliding with its smaller companion NGC 7715. A similar cataclysmic collision is due to take place between our own galaxy – the Milky Way – and our closest neighbor, the Andromeda galaxy, in around four billion years. The image itself is a composite, comprised of a number of images captured by Hubble over a wide range of wavelengths.
NGC 7715 is categorized as a Wolf-Rayet starburst galaxy due to the large, extremely hot and relatively short-lived stars that make up the celestial giant. Somewhere between 100 to 200 million years ago, NGC 7715 drifted too close to its galactic neighbor NGC 1174, triggering a dramatic change in the galaxy's structure.
As the two galaxies approached each other, the colossal forces emanating from the wandering giants tortured and disrupted each other's structures, leaving us with the irregularly-shaped galaxies we have today. The larger galaxy has had two long tails of stars ripped away, flinging vast amounts of material out into the space between the giants.
This in turn has formed a sort of galactic bridge, funneling materials from the smaller galaxy and feeding a bright burst of star formation in NGC 7714. The formation is predominantly taking place in the galactic center of NGC 7714, however the process is evident throughout the entire galaxy to a lesser extent.
It is a comforting thought that, in four billion years when we collide with our closest neighbor Andromeda, we may find ourselves ushering in a fresh explosion of star formation in the now-distant galaxy. | 0.812236 | 3.477601 |
LADEE impact site on the eastern rim of Sundman V crater, the spacecraft was heading west when it impacted the surface. The image was created by ratioing two images, one taken before the impact and another after the impact. The bright area shows the impact point and the ejecta (things that have changed between the time of the two images). The ejecta form a V shaped pattern extending to the northwest from the impact point. Ratio constructed with LROC images M1163066820RE and M1101816767RE (NASA/GSFC/Arizona State University).
The Lunar Atmosphere and Dust Environment Explorer (LADEE) was launched from Wallops Island on 6 September 2013 at 11:27 EDT and was visible over much of the eastern coast of the United States. The spacecraft was 2.37 m (7.8 ft) high and 1.85 m (6.1 ft) wide with a mass of 383 kg (844 lb) including the fuel. After expending most of its fuel during its successful exploration of the Moon the spacecraft had a mass of about only 248 kg (547 lb) when it impacted the surface.
Originally LADEE was placed into a retrograde, near-equatorial orbit to study the Moon’s surface bound exosphere and dust environment. Since the Apollo era of exploration several conflicting ideas and observations concerning the existence (or not) of near-surface and high altitude dust were debated, and thus one of LADEE’s key science goals was to search for dust particles high above the surface (no dust was found).
LADEE’s engines were fired on 11 April 2014 to adjust the orbit in such a way as to guarantee a farside impact if the spacecraft did not survive the 15 April 2014 eclipse. There was a small worry that if the spacecraft failed during the eclipse and was uncontrollable, it might impact near one of the Apollo sites. Over the subsequent 7 days, the low point in LADEE’s orbit decreased resulting in an impact on 18 April 2014.
As it passed over the western limb as seen from the Earth, the spacecraft impacted the eastern rim of Sundman V crater (11.85°N, 266.75°E). The impact site (11.8494°N, 266.7507°E) is about 780 m from the crater rim with an altitude of about 2590 m, and was only about 295 meters north of its originally predicted location (based on tracking data).
Like the LADEE spacecraft, the impact crater is small, <3 m in diameter, barely resolvable by the LROC NAC. Based on impact models, a crater of only about 1.8 m (6 ft) diameter is expected. The crater is very small because, as impacts go, LADEE had a low mass and a low density (0.43 g / cm3 vs. >3.0 g / cm3 for an ordinary chondrite meteorite), and was traveling at only a tenth the speed (1699 m/sec – 3800 mph) of an average asteroid.
Because it is so small, the crater is hard to identify among the myriad of small fresh craters that dot the lunar surface. However, as images had been acquired of the impact region before the impact occurred, they could be compared with images acquired after the impact to identify the crater.
Since NAC images are so large (250 megapixels) and the new crater is so small the LROC team coregistered the before and after images (called a temporal pair) and then divided the after image by the before image. In this manner any changes to the surface stick out like a beacon! For the LADEE crater the ejecta forms a triangular pattern primarily downrange (to the west) extending more than 200 meters from the impact site. There is also a small triangular area of ejecta uprange but it extends only about 20-30 meters. The ejecta pattern is oriented WNW consistent with the direction the spacecraft was traveling when it impacted.
See additional images and more information on the LROC News Page
Posted by: Soderman/SSERVI Staff
Source: LROC News Page | 0.815085 | 3.728549 |
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