Astronomers and the space-obsessed turned their attention to the skies on Tuesday for what NASA called a "rare opportunity". An asteroid was coming — and this wasn't a pipsqueak. Roughly the size of a mountain, more than 330 metres wide, scientists had tracked its progression for the past 11 years.
But even with the warning, it still came with a surprise. The asteroid didn't come alone — it brought is own moon. The first radar images, captured when the asteroid was at a distance of almost 1,300,000 kilometres, showed a small bulb of light hovering above its surface. The moon wasn't a big one, NASA reported, just 70 metres across.
"The flyby was the closest approach the asteroid will make to Earth for at least the next two centuries," NASA said. "It is also the closest a known asteroid this size will come to Earth until asteroid 1999 AN10 flies past our planet in 2017." So we'll have to wait awhile for something like this to happen again.
Twenty images generated from data collected by NASA's Deep Space Network show Asteroid 2004 BL86 and its moon.
Those with a clear view may not have seen much. According to Sky and Telescope Magazine, the asteroid was actually closest to Earth at around 3am Tuesday AEST, then grew brighter the farther away it got.
Still, the moon was nice to see for those who were able. "Previous studies of the light around [the asteroid] already identified a moon orbiting the asteroid, and the new images confirm the discovery," NASA scientist Lance Benner told Space.com.
The asteroid didn't come close to hitting us this time, but that may change in the future, scientists cautioned. "Now that we have the radar data from both last night and tonight, we'll be able to predict this much further into the future," Paul Chodas of JPL's Near-Earth Object Program told Space.com. "And over the centuries, and as far as a millennia, this asteroid will be approaching slightly closer each time. So it's definitely one we'll want to keep our eye on."
The Washington Post
