Half the size of a football field, the massive asteroid known as 2012 DA14 will pass about 17,000 miles above Earth traveling five miles per second. Scientists at NASA will be taking radar imagery to learn more and eventually help avoid impact from future asteroids. NBC's Kristen Dahlgren reports.
By Alan Boyle, Science Editor, NBC News
The best way for most of us to watch asteroid 2012 DA14 come within 17,200 miles of Earth on Friday, and then recede harmlessly into the cosmos, is to fire up your Web browser and watch the show online. Pictures of the space rock, which is about half the length of a football field, are already starting to roll in.
NASA's experts on near-Earth objects say that the time of closest approach will come at 2:25 p.m. ET, when the asteroid is zooming above the eastern Indian Ocean at a speed of almost 17,500 mph (7.8 kilometers per second). It'll be too dim to see with the naked eye, but observers in Australia, Asia and Europe might be able to follow it with binoculars or small telescopes if they know exactly where to look. (If you want to try it, follow the directions at the bottom of this item.)
Then there are the professionals: Astronomers around the world are tracking 2012 DA14 with optical telescopes and radar dishes to learn more about the asteroid's color, shape, spin and reflectivity. Such data could tell them what the object is made of, and perhaps provide insights into how similar objects could be diverted if they were on a threatening course. Which this one is not.
Experts estimate that asteroids the size of 2012 DA14 hit our planet every 1,200 years or so, exploding with the energy of a 2.5-megaton atomic bomb: The last such impact struck a remote region of Siberia without warning in 1908, flattening 820 square miles of forest. If an object that big were to hit in just the wrong place, it could wipe out a city. Coincidentally, a much smaller meteoroid came down over Russia on Friday, sparking a fireball and a glass-shattering shock wave.
Even though the 150-foot-wide (45-meter-wide) asteroid is the biggest object of its kind to be seen coming this close to Earth, its orbit is so well-known that NASA's Near-Earth Object Program can rule out any chance of collision in the foreseeable future. And even though 2012 will fly 5,000 miles closer than satellites in geosynchronous orbit, NASA says its mostly south-to-north orbital path goes through a "sweet spot" that keeps it far away from those satellites ??as well as from other spacecraft that are in closer orbits, including the International Space Station.
Thus, astronomers don't expect to see anything go boom on Friday. But they could pick up on some subtler phenomena, such as seismic disturbances in the asteroid that are induced by Earth's gravitational kick, or characteristics of the asteroid's spin that are affected by radiation absorption and emission.
This animated set of three images shows 2012 DA14 as it was observed by the Faulkes Telescope South in Australia on Feb. 14 at a distance of 465,000 miles. The asteroid is the moving bright spot in the middle. NASA's website provides details. Credit: LCOGT / E. Gomez / Faulkes South / Remanzacco Observatory.
Radar readings provide the best way to get a fix on the asteroid's shape and spin, in part because observations from multiple radio telescopes can be combined to produce a clearer picture. During 2012 DA14's flyby, radio telescopes in California, New Mexico and Puerto Rico will be tracking the asteroid. NASA's 230-foot (70-meter) dish at Goldstone, Calif., is expected to collect radar imagery good enough to produce a 3-D movie mapping the space rock from all sides.
Other telescopes, spread out from Australia to Israel to the Canary Islands to the U.S., will be gathering optical data ? and the images from some of those telescopes will be shared on Friday. Here's the viewing schedule:
Noon ET: NASA plans to start streaming near-real-time?imagery of the asteroid's flyby, as provided by telescopes in Australia and Europe, weather permitting. Watch JPL video on Ustream.
2 p.m. ET:?To mark the time of closest encounter, NASA will present a half-hour program with commentary from the Jet Propulsion Laboratory. The show will feature computer animations as well as any live or near-real-time imagery that becomes available from telescopes in Australia. Watch video on NASA.gov or Ustream.?(NBCNews.com also plans to stream the show.)
3:15 p.m. ET: The Bareket Observatory in Israel says it will air a three-hour webcast featuring imagery from the flyby. Static images of the asteroid and its celestial surroundings will be refreshed every 30 to 60 seconds. Watch Bareket's webcast.
5 p.m. ET: The Virtual Telescope Project 2.0 will present live video of the asteroid flyby from a telescope in Italy, weather permitting. Video site: Watch Virtual Telescope Project's webcast.
6 p.m. ET: Weather permitting, the Clay Center Observatory in Massachusetts?will stream real-time, high-definition video from 6 p.m. ET until 4 a.m. ET Saturday. Watch Clay Center video on Ustream.
9 p.m. ET: Slooh Space Camera plans to present several live shows about the asteroid flyby, accompanied by expert commentary. Weather permitting, imagery will be beamed to Slooh HQ from telescopes on the Canary Islands and in Arizona. Watch the show on Slooh.com.
9 p.m. ET: A video feed of the flyby from a telescope at NASA's Marshall Space Flight Center will be streamed for three hours. During the live-streaming event, viewers can ask researchers questions about the flyby via Twitter or the Ustream chat window. Watch Marshall's Ustream channel.
Got any other websites worth watching? Or any asteroid questions you're wondering about? Feel free to share them in your comments below.
More about the asteroid encounter:
Astronomers say asteroid 2012 DA14 won't be visible to the naked eye, but it is possible to watch it pass by through binoculars or a small telescope ? if you know where and when to look. TheHeavens-Above?website can help you get a fix on the fast-moving rock. First, go to the website'slocation database?and find the nearest city. Click on the link for that city. Then, click on over to the2012 DA14 sky chart?and look for the asteroid's track, with notations that indicate observation times. If you don't see the asteroid's track, you won't be able to see the asteroid. In some cases, the track is shown during daylight hours?? which would generally rule out visual observations.
Universe Today is providing a detailed guide to viewing opportunities.
Alan Boyle is NBCNews.com's science editor. Connect with the?Cosmic Log?community by "liking" the log's?Facebook page, following?@b0yle on Twitter?and adding the?Cosmic Log page?to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space,?sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out?"The Case for Pluto,"?my book about the controversial dwarf planet and the search for new worlds.
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