NEWS & PRESS 
 
 Two astronomers at Columbia University in New York suggest humanity could use lasers to conceal the Earth from searches by advanced extraterrestrial civilisations. Professor David Kipping and graduate student Alex Teachey make the proposal in a paper in Monthly Notices of the Royal Astronomical Society. 
 
 Several prominent scientists, including Stephen Hawking, have cautioned against humanity broadcasting our presence to intelligent life on other planets. Other civilisations might try to find Earth-like planets using the same techniques we do, including looking for the dip in light when a planet moves directly in front of the star it orbits. 
 
 These events – transits – are the main way that the Kepler mission and similar projects search for planets around other stars. So far Kepler alone has confirmed more than 1,000 planets using this technique, with tens of these worlds similar in size to the Earth. Kipping and Teachey speculate that alien scientists may use this approach to locate our planet, which will be clearly in the 'habitable zone' of the Sun, where the temperature is right for liquid water, and so be a promising place for life. 
 
 Hawking and others are concerned that extraterrestrials might wish to take advantage of the Earth’s resources, and that their visit, rather than being benign, could be as devastating as when Europeans first travelled to the Americas. 
 
 The two authors of the new study suggest that transits could be masked by controlled laser emission, with the beam directed at the star where the aliens might live. When the transit takes place, the laser would be switched on to compensate for the dip in light. 
 
 A 22W laser used for adaptive optics on the Very Large Telescope in Chile. A suite of similar lasers could be used to alter the shape of a planet's transit for the purpose of broadcasting or cloaking the planet. Credit: ESO / G. HüdepohlAccording to the authors, emitting a continuous 30 MW laser for about 10 hours, once a year, would be enough to eliminate the transit signal, at least in visible light. The energy needed is comparable to that collected by the International Space Station in a year. A chromatic cloak, effective at all wavelengths, is more challenging, and would need a large array of tuneable lasers with a total power of 250 MW. 
 
 "Alternatively, we could cloak only the atmospheric signatures associated with biological activity, such as oxygen, which is achievable with a peak laser power of just 160 kW per transit. To another civilisation, this should make the Earth appear as if life never took hold on our world", said Alex. 
 
 As well as cloaking our presence, the lasers could also be used to modify the way the light from the Sun drops during a transit to make it obviously artificial, and thus broadcast our existence. The authors suggest that we could transmit information along the laser beams at the same time, providing a means of communication. 
 
 David comments: "There is an ongoing debate as to whether we should advertise ourselves or hide from advanced civilisations potentially living on planets elsewhere in the Galaxy. Our work offers humanity a choice, at least for transit events, and we should think about what we want to do." 
 
 Given that humanity is already capable of modifying transit signals, it may just be that aliens have had the same thought. The two scientists propose that the Search for Extraterrestrial Intelligence (SETI), which mostly currently looks for alien radio signals, could be broadened to search for artificial transits. 
 
 Media contact 
 
 Dr Robert Massey 
 
 Royal Astronomical Society 
 
 Tel: +44 (0)20 7734 3307 
 
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 Science contacts 
 
 Prof David Kipping 
 
 Department of Astronomy 
 
 Columbia University 
 
 New York 
 
 United States 
 
 Tel: +1 212-854-6899 
 
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 Alex Teachey 
 
 Department of Astronomy 
 
 Columbia University 
 
 New York 
 
 United States 
 
 Tel: +1 804-366-0404 
 
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 Images and captions 
 
 A 22W laser used for adaptive optics on the Very Large Telescope in Chile. A suite of similar lasers could be used to alter the shape of a planet's transit for the purpose of broadcasting or cloaking the planet. Credit: ESO / G. Hüdepohl 
 
 Further information 
 
 The new work appears in "A Cloaking Device for Transiting Planets", David M. Kipping and Alex Teachey, Monthly Notices of the Royal Astronomical Society, Oxford University Press, in press. 
 
 Notes for editors 
 
 The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3900 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others. 
 
 The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content. 
 
 Follow the RAS on Twitter 
 
 ||||| A view of the Gulf of Mexico and US Gulf Coast at sunset from the International Space Station taken by Expedition 42 Flight Engineer Terry W. Virts, in a NASA photo obtained December 17, 2014 (AFP Photo/Terry Virts) More 
 
 Paris (AFP) - The fate of humanity if aliens were to discover Earth with its balmy climate and bountiful resources, has long been a concern for scientists -- many of whom fear the worst. 
 
 Physicist Stephen Hawking is among those to have warned that ET and his friends may be much more intelligent than us, and may view human beings as little more than troublesome bugs. 
 
 Now a pair of astronomers from Columbia University in New York have proposed an innovative method to hide our planet from prying extraterrestrial eyes -- using massive lasers. 
 
 And it's not a joke, they say. 
 
 Alien scientists, argued David Kipping and Alex Teachey, may be trying to find habitable planets using the same technique we do -- searching for a slight dip in light when a planet "transits" between the star it orbits and the telescopes watching it. 
 
 Planets do not emit their own light and, if they were visible to the naked eye, would appear as dark dots tracking across their bright stars. 
 
 But these exoplanets are too far away to see, and all our telescopes can pick up is a small decrease in the starlight emitted during transit. 
 
 If aliens spot us using this technique, Earth would be a logical target for alien settlement. 
 
 It orbits within the so-called "habitable zone" -- not too close nor too far from the Sun -- where the temperature is right for liquid water, the essence of life. 
 
 In a paper published Thursday in the Monthly Notices of the Royal Astronomical Society (RAS) in London, Kipping and Teachey said Earth's Sun transits could be masked by shining huge lasers to cover the dip in light. 
 
 - Strange but true - 
 
 "Despite the timing, it's really not an April Fool's joke," RAS deputy executive director Robert Massey assured AFP on Friday. 
 
 "This is a serious piece of work." 
 
 Humanity's search for a planet capable of hosting life remains an academic pursuit -- there is no solar system near enough to reach without time travel. 
 
 Since its launch in 2009, NASA's Kepler exoplanet-hunting space telescope has found thousands of candidates. 
 
 Astronomers have verified the existence of nearly 2,000 faraway worlds, but most of those orbiting in habitable zones have been gas giants. 
 
 "The transit method is presently the most successful planet discovery and characterisation tool at our disposal," wrote the duo. 
 
 "Other advanced civilisations would surely be aware of this technique..." 
 
 Within the wavelength spectrum of visible light, the transit signal could be masked with a monochromatic laser emitting about 30 million watts (MW) for 10 hours at a time, once a year. 
 
 One MW can power several hundred homes for an hour. 
 
 A universal cloak effective at all wavelengths, would require a much larger array of lasers with a total output of 250 MW, said the team. 
 
 "There is an ongoing debate as to whether we should advertise ourselves or hide from advanced civilisations potentially living on planets elsewhere in the Galaxy," Kipping said in a statement. 
 
 "Our work offers humanity a choice, at least for transit events, and we should think about what we want to do." ||||| Published on Mar 31, 2016 
 
 NSF Graduate Fellow Alex Teachey of the Cool Worlds Lab explains our new paper which devises a method to cloak entire planets from extraterrestrial civilizations! This was a really fun little paper which started out from the idea of how to broadcast or signal our presence, but as we worked on it we realized it could also be used a cloaking device too. As always, ask us your questions in the comments below and we'll get back to you! 
 
 
 
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 ► Kipping & Teachey (2016): "A Cloaking Device for Transiting Planets" http://arxiv.org/abs/1603.08928 
 
 ► BBC article on Stephen Hawking's comments about avoiding alien contact: http://news.bbc.co.uk/2/hi/8642558.stm 
 
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 THANKS FOR WATCHING!! ||||| A new paper describes how laser beams could disrupt measurements of Earth's orbit around the sun, potentially deceiving inquisitive aliens. Here, a 22W laser used for adaptive optics shines from the Very Large Telescope in Chile. 
 
 A simple laser beam could disrupt aliens' observations of Earth, making it look like there's nobody home on the third rock from the sun, a new study suggests. 
 
 David Kipping, an astronomer at Columbia University in New York, said he first considered this idea when he heard about the strangely dimming star that was detected recently by NASA's Kepler space telescope. Researchers speculated the signal could have come from an "alien megastructure" orbiting the star. 
 
 That's a remote possibility, many scientists stressed; the star's strange signal likely has a natural cause. But the Kepler observations got Kipping thinking about ways humanity could alter the signals it sends into space — or hide them altogether from life-hunting aliens, who may have malicious intentions. [13 Ways to Hunt Intelligent Aliens] 
 
 He and Columbia graduate student Alex Teachey concluded that it would be surprisingly easy to wipe out Earth's signal, distort it to look strange or even edit out the fingerprint of life — provided researchers knew the location of the snooping aliens. 
 
 "We essentially played the thought experiment that if we really had xenophobic tendencies and wanted to avoid the Earth being discovered (as Stephen Hawking and others have been warning about), could we hide the Earth from alien planet-hunters?" Kipping said in an email. 
 
 The key to Kipping and Teachey's thinking lies in the way humans have identified most planets around other stars, a process called the transit method. This strategy, which has most famously been employed by the Kepler spacecraft, detects tiny dips in the brightness of stars, which can indicate an orbiting planet. 
 
 The transit method could theoretically be used by alien civilizations to detect Earth, too. But there's a way to trip up such extraterrestrial searches, Kipping and Teachey said. 
 
 "To make it look like the planet is not there at all, you've got to get rid of that dip. You've got to fill in the missing starlight," Teachey said in an explanatory video. 
 
 NASA's Kepler space telescope uses small dips in a star's brightness to detect planets passing in front of the star. Each planet will leave a distinctive light signature. Credit: Alex Teachey/Columbia University via YouTube 
 
 Engineers could shine a very bright laser or collection of lasers toward a star suspected of hosting intelligent aliens during the time Earth was passing in front of the sun from the other planet's perspective. Then, aliens making measurements wouldn't see any change in solar brightness. 
 
 "I started to think about lasers," Kipping told Space.com. "Most people might have stopped there, because the sun emits so much light — how could you possibly produce a laser beam which could ever compete with the sun? But it turns out, when you actually run through the equations, it's really not that bad." [How to Discover an Alien Planet (Video)] 
 
 "We could build this next week if we wanted to," Teachey added. 
 
 To alter Earth's signature as seen by an alien version of Kepler, a laser system would have to emit 30 megawatts of power for about 10 hours per year, coinciding with Earth's passing in front of the sun, the duo calculated. 
 
 That equates to significantly less than the energy the International Space Station gathers in a year with its solar panels, Kipping said, or the energy used by about 70 homes over the course of a year. Such a laser system, either on Earth or in orbit, could charge its solar-powered batteries for most of the year and then release the high-powered blasts at just the right time, brightening when the sun's light would normally dim. 
 
 While a laser of that intensity hasn't been built before, the researchers said, such a cloaking system could also use multiple smaller lasers, all shining in the same direction. The alien star would be so distant that such a difference would be indistinguishable. Laser beams are tightly focused, but at greater distances, the beams will have grown large enough to require less precise aim. 
 
 Shining a laser beam toward a planet whose inhabitants might see the Earth pass in front of the sun could replace the light the Earth blocks out. This would conceivably hide the planet. Using different laser wavelengths can create other illusions with the Earth's transit. Credit: Alex Teachey/Columbia University via YouTube 
 
 By varying the wavelength and strength of the beams, humans could conceal Earth from more complicated detectors. Such a "cloak" that concealed all wavelengths would take about 250 megawatts of power, with lasers blasting at different wavelengths, the researchers said. The laser strategy could also alter Earth's signature to look like almost anything, even something that appears distinctive and artificial, the scientists said, like the New York skyline or a featureless box. 
 
 But perhaps the most interesting use, the researchers said, would be as a "bio-cloak," which would actually use less power than would be required to totally conceal the planet. When a planet crosses its star's face, a little bit of light passes through the planet's atmosphere, and researchers can determine the atmosphere's makeup based on the wavelengths of that light. By sending laser beams that are the inverse of certain wavelengths, humanity could conceivably edit out the life-generated "biosignatures" in Earth's atmosphere, Kipping said. 
 
 "We can actually cancel those features out, such as oxygen," he said. "The alien civilization is going to detect your planetary transit. They're going to detect your planetary radial velocity, but then when they 'smell' the atmosphere, it would not look like a tasty planet. It would just look like a dead world." 
 
 While a planet that was fully cloaked could still be detected by other means, such as by the gravitational pull it exerts on its star, this kind of cloak would arouse less suspicion, because the planet would be there as expected, just without signs of life. 
 
 "We feel like this is the most deceptive cybercloaking you could possibly do, because then everything adds up — there's no missing piece to the puzzle," Kipping said. "And that would be a very difficult cloak to see." [10 Exoplanets That Could Host Alien Life] 
 
 Kipping and Teachey laid out their thinking in a study published Thursday (March 31) in the journal Monthly Notices of the Royal Astronomical Society. 
 
 
 
 Yes - We may not have found them yet, but they're out there. 
 
 No - Aliens are just part of science fiction. 
 
 I'm not sure 
 
 
 
 Concealing Earth's existence from extraterrestrials, or announcing its presence with an artificial light curve, would work only if humanity knew or suspected where those aliens were living. But the concept is still intriguing as scientists look out to read other stars' light signatures and speculate about alien astronomers reading signals from Earth. 
 
 Kipping and Teachey suggested that alien civilizations could communicate with each other during transits by varying their light signatures, because individuals investigating a planet are likely to watch it as it passes in front of its star. Alien lasers could even encode information to transmit, the researchers said. 
 
 One possible next step, they added, would be to look more carefully through archival Kepler data to search for artificial signatures. 
 
 Jason Wright, an astronomer from Pennsylvania State University, recently published a paper about how scientists could identify advanced civilizations around other stars. "Alien megastructures" would dim stars more than expected, whereas lasers would tend to brighten them, but "we should look for both," Wright told Space.com. 
 
 "The fact that Kepler looked at 100,000 stars and didn't see much of anything along those lines suggests that that is pretty rare in the galaxy," Wright added. "And we should look more closely to see if there are things that aren't totally obvious." 
 
 In terms of this particular technology on Earth, "The only time it'd be useful for us is if we had some knowledge of alien civilizations along the thin strip of the sky that would see Earth transit the sun," he said. 
 
 Avi Loeb, who chairs the astronomy department at Harvard University in Massachusetts, told Space.com that the laser-cloaking method assumes researchers know where to look, that aliens aren't observing from moving spaceships and that putative extraterrestrial observers are mainly investigating planets by looking for transits across stars. 
 
 Energy demands would quickly grow as a civilization tried to hide from, or signal to, an increasing number of star systems, Loeb added. But the laser cloak is still an interesting new idea to add to the arsenal in the search for extraterrestrial life, he said. 
 
 "If there is a literature of ideas like this one, ideas that people proposed for potential signals that are artificial — the richer the literature is, the better it is," Loeb said. "The moment we find something artificial, it will change everything. It's good to have the imagination at work prior to seeing something unusual, so we are aware that there are possibilities beyond what we expect." 
 
 "I don't think anyone's thought of this particular application before," Wright said. "I think it just emphasizes how little energy is actually required to get someone's attention across the galaxy." 
 
 Email Sarah Lewin at slewin@space.com or follow her @SarahExplains. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.
– Human history shows that when two civilizations meet for the first time, it doesn't always turn out that well for one of them. And plenty of scientists—Stephen Hawking included—fear that humankind may end up on the losing side of a meeting with extraterrestrials. Now a couple of astronomers from Columbia University have put forth an idea they say could keep aliens from locating Earth in the first place: use giant lasers to hide the planet. The paper by David Kipping and Alex Teachy was published in the Monthly Notices of the Royal Astronomical Society on March 31. ("Despite the timing," the society's executive director tells AFP, "it's really not an April Fool's joke.") Kipping and Teachy's idea centers on the transit method, which is how humans, via NASA's Kepler spacecraft, search for habitable planets, reports Space.com. It involves detecting dips in the brightness of a star caused when an orbiting planet moves directly in front of it. A giant laser or group of lasers would "fill in the missing starlight," Teachy says in a video outlining the idea. Depending on how thoroughly you wanted to conceal the Earth, it would take anywhere from 30 to 250 megawatts emitted for 10 hours, once a year. Lasers can even be used to cancel out attributes "such as oxygen," Teachy says in a press release, to make Earth appear to be a "dead world." But their idea could also be applied in reverse: The sun's light could be manipulated as we passed in such a way that would make it clear something artificial was happening, signaling our presence. (These celebrities say they've already had close encounters with ETs.)