On the afternoon of Oct. 31, 2015, Earth was visited by something much creepier than the typical Halloween trick-or-treater: a dark 2,000-foot (600-meter) wide asteroid that sped silently by, approaching at its closest about 1.3 times the distance to the moon.
Designated 2015 TB145, this particular near-Earth object had only just been discovered a couple of weeks earlier. And while it posed no danger of impact, its considerable size and high velocity - 78,000 mph, or almost 35 kilometers per second - as well as its "spooky" scheduling made the close pass a topic of online interest.
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But besides casual discussions of global destruction via cosmic impact (which, by the way, this object would not have caused even if it had been on a collision course) NASA astronomers did take the opportunity to learn more about this new found asteroid during its brief visit. By bouncing radar waves off its surface researchers were able to generate an image of 2015 TB145, capturing details that would have been otherwise impossible due to its high velocity and incredibly dark coloration.
"The radar images of asteroid 2015 TB145 show portions of the surface not seen previously and reveal pronounced concavities, bright spots that might be boulders, and other complex features that could be ridges," said Lance Benner, who leads NASA's asteroid radar research program at the Jet Propulsion Laboratory in Pasadena, Calif.
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The images above were created from radar observations made by transmissions from the Deep Space Network's 230-foot (70-meter) DSS-14 antenna at Goldstone, Calif. The radar waves from DSS-14 were reflected off the approaching 2015 TB145 and collected by the National Radio Astronomy Observatory's 100-meter (330-foot) Green Bank Telescope in West Virginia.
Images made from data acquired by the National Science Foundation's 1,000-foot (305-meter) antenna at the Arecibo Observatory in Puerto Rico the previous day showed a slightly different perspective of 2015 TB145 - in which it bore a resemblance to a human skull. (Its Halloween costume, perhaps?)