A mammoth asteroid safely sailed past Earth on Monday, and scientist have started to look at information gleaned from the flyby that may help curb future risks of an impact.
Known as 2004 BL86, the space rock posed no danger to us Earthlings, passing at a distance of 745,000 miles (1.2 million kilometers) at 11:19 a.m. EST. While this may sound like a comfortable distance—it’s about three times the distance of the moon from the Earth—it is considered a cosmic squeaker.
Early radar observations by NASA, which used some of the world’s largest radio telescopes to view the asteroid, have shown some surprises. For instance, the rock measures some 984 feet (300 meters) across, rather than the earlier estimate of 1,600 feet (500 meters).
The early images also show what looks like a companion moon next to the asteroid. And they reveal that the asteroid is tumbling so fast that a day on its surface is no more than 2.6 hours long.
Backyard sky-watchers will have a chance to see the giant rock on Monday night when, for several hours, BL86 will reach a visual brightness of magnitude 9. That means small telescopes and possibly even large binoculars will reveal the asteroid—as long as you know where to look.
Monday’s pass is considered the closest that an asteroid this large will get to Earth until the year 2027, when the space rock known as 1999 AN10 whips by our planet within the moon’s orbit.
That’s a pretty close call. So should we be paying more attention to the potential threat of an asteroid hitting our planet? Here are a few basic questions and answers.
What are scientists hoping to learn from Monday’s close encounter?
NASA scientists are using the radio telescopes to bounce radar signals off the asteroid’s surface so they can map it out in detail. They want to get a much clearer idea of its shape and size and how it is tumbling through space.
The information will be critical for the future asteroid retrieval mission that NASA has planned in the next decade, when scientists will get their hands on their first samples from these ancient cosmic rocks.
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SOURCE: National Geographic | Andrew Fazekas