Table Legend Coloration The color of the table entries gives a rough interpretation of the severity of the threat. Small objects are not likely to cause significant damage in the event of an impact, although impact damage does depend heavily upon the specific (and usually unknown) physical properties of the object in question. Small Objects Torino Scale Colors Estimated diameter 50 meters or less. 0 1 2,3,4 5,6,7 8,9,10 
 
 Object Designation Temporary designation or permanent number for this object. Assigned by the Minor Planet Center. 
 
 
 
 Year Range Time span over which impacts have been detected. Typically, searches are conducted 100 years into the future. 
 
 
 
 Potential Impacts The number of dynamically distinct potential impacts that have been detected by Sentry. There can be several qualitatively unique pathways to impact in a given year, e.g., some with an extra revolutions around the sun, others deflected to impact by an earlier planetary encounter. 
 
 
 
 Impact Prob. (cum.) The sum of the impact probabilities from all detected potential impacts. 
 
 
 
 V infinity The velocity of the asteroid relative to the Earth, assuming a massless Earth. 
 
 
 
 H Absolute Magnitude is an intrinsic measure of brightness. It is the apparent magnitude of the object when it is 1 AU from both the sun and the observer, and at full phase for the observer. 
 
 
 
 Est. Diam. The estimated diameter of the asteroid. This is an estimate based on the absolute magnitude, usually assuming a uniform spherical body with visual albedo p V = 0.154 (in accordance with the Palermo Scale) but sometimes using actual measured values if these are available. Since the albedo is rarely known for objects on this page, the diameter estimate should be considered only approximate, but in most cases will be accurate to within a factor of two. 
 
 
 
 Palermo Scale (cum.) & (max.) The cumulative and maximum hazard ratings according to the Palermo Technical Impact Hazard Scale. 
 
 
 
 Torino Scale (max.) The maximum detected hazard rating using the Torino Impact Hazard Scale. According to this ten-point scale, a rating of zero indicates the event has "no likely consequences." A Torino Scale rating of 1 indicates an event that "merits careful monitoring." Even higher ratings indicate that progressively more concern is warranted. The Torino Scale is defined only for potential impacts less than 100 years in the future. ||||| NASA's New 'Intruder Alert' System Spots An Incoming Asteroid 
 
 Enlarge this image toggle caption P. Carril/ESA P. Carril/ESA 
 
 A large space rock came fairly close to Earth on Sunday night. Astronomers knew it wasn't going to hit Earth, thanks in part to a new tool NASA is developing for detecting potentially dangerous asteroids. 
 
 The tool is a computer program called Scout, and it's being tested at NASA Jet Propulsion Laboratory in Pasadena, Calif. Think of Scout as a celestial intruder alert system. It's constantly scanning data from telescopes to see if there are any reports of so-called Near Earth Objects. If it finds one, it makes a quick calculation of whether Earth is at risk, and instructs other telescopes to make follow-up observations to see if any risk is real. 
 
 NASA pays for several telescopes around the planet to scan the skies on a nightly basis, looking for these objects. "The NASA surveys are finding something like at least five asteroids every night," says astronomer Paul Chodas of JPL. 
 
 But then the trick is to figure out which new objects might hit Earth. 
 
 "When a telescope first finds a moving object, all you know is it's just a dot, moving on the sky," says Chodas. "You have no information about how far away it is. "The more telescopes you get pointed at an object, the more data you get, and the more you're sure you are how big it is and which way it's headed. But sometimes you don't have a lot of time to make those observations. 
 
 "Objects can come close to the Earth shortly after discovery, sometimes one day, two days, even hours in some cases," says JPL's Davide Farnocchia. "The main goal of Scout is to speed up the confirmation process." 
 
 The rock that whizzed past Earth tonight was discovered on the night of Oct. 25-26 by the NASA-funded Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) on Maui, Hawaii. Within a few hours, preliminary details about the object appeared on a Web page maintained by the Minor Planet Center at the Smithsonian Astrophysical Observatory. Scout did a quick analysis of the preliminary details and determined that the object was headed for Earth but would miss us by about 310,000 miles. 
 
 Enlarge this image toggle caption Rob Ratkowski/Courtesy of Pan-STARRS Rob Ratkowski/Courtesy of Pan-STARRS 
 
 Additional observations by three telescopes, one operated by the Steward Observatory, another called Spacewatch, and a third at the Tenagra Observatories, confirmed the object would miss Earth by a comfortable margin. Astronomers were also able to estimate the size of the object: somewhere between 5 meters and 25 meters across. In case you're interested, full details about the object's trajectory can be found here. 
 
 Scout is still in the testing phase. It should become fully operational later this year. 
 
 Now Scout is mainly dealing with smallish, very nearby objects. Complementing Scout is another system that is already operational called Sentry. 
 
 Sentry's job is to identify objects large enough to wipe out a major city that might hit Earth in the next hundred years. "Our goal right now is to find 90 percent of the 140-meter asteroids and larger," says Chodas, but right now he estimates they're able to find only 25 to 30 percent of the estimated population of objects that size. 
 
 That number should get better when a new telescope being built in Chile called the Large Synoptic Survey Telescope comes online. NASA is also considering a space telescope devoted to searching for asteroids. 
 
 OK, so let's say you find one of these monster rocks heading for Earth. What then? Astronomer Ed Lu says there is something you can do. He's CEO of an organization called B612. It's devoted to dealing with asteroid threats. 
 
 "If you know well in advance, and by well in advance I mean 10 years, 20 years, 30 years in advance, which is something we can do, " says Lu, "then you can divert such an asteroid by just giving it a tiny nudge when it's many billions of miles from hitting the Earth." 
 
 NASA and the European Space Agency are developing a mission to practice doing just that. 
 
 Lu says in the past decade, people who should worry about such things have begun to make concrete plans for dealing with dangerous asteroids. 
 
 "I believe in the next 10 to 15 years we'll actually be at the point where we as humans can say, 'Hey, we're safe from this danger of large asteroids hitting the Earth,' " he says. 
 
 In the meantime, we'll just have to hope that luck is on our side.
– NASA is hard at work to protect the Earth from asteroid threats, NPR reports. The agency's new "Scout" detection system scans the skies above our planet for small, nearby objects that might enter Earth's orbit. In fact, a small one between 5 and 25 meters across will come relatively close to Earth Sunday night, though there's no danger of a strike. Once an asteroid is detected, Scout coordinates data from multiple telescopes across the world in order to ascertain if the object will enter Earth's atmosphere, and if it poses any sort of a threat. While more than 15,000 Near-Earth Objects have been recorded over the course of history, astronomers say many, many more pass by undetected. This year alone, scientists have discovered more than 1,500 NEOs, the Christian Science Monitor reports. That number doesn't mean that the end of days is coming—it just means scientists are getting better at detecting and monitoring objects that come into our celestial neighborhood. While the new "Scout" system looks at smaller objects, NASA's older, heavy-duty "Sentry" system looks for big, far-away asteroids which might pose a threat to Earth. And if any are ever detected? NASA and the ESA are jointly working on a method to re-direct large asteroids.