The object 2015 TB145 wasn't discovered until Oct. 10, and its flyby promises to be a very cool event for people who study hurtling space rocks. It's going to come within 1.3 lunar distances of the Earth, and it measures some 1,300 feet in diameter. That means NASA can hope to snag some pictures of the asteroid on its way past us and could probably study it.
"This is the closest approach by a known object this large until 1999 AN10 approaches within 1 lunar distance in August 2027," NASA's report states. "The last approach closer than this by an object with H < 20 was by 2004 XP14 in July 2006 at 1.1 lunar distances."
The encounter velocity (around 22 miles per second) is considered "unusually high," and it has an "extremely eccentric" orbit, which may have contributed to its late detection. But NASA isn't sounding any alarms on this one: There's no reason to think our spooky close encounter will turn into a doomsday scenario.
In fact, those eccentricities might mean that the flyby is an extra special one. The asteroid could be a comet in disguise.
"Such a unique orbit, along with its high encounter velocity — about 35 kilometers or 22 miles per second — raises the question of whether it may be some type of comet," Lance Benner, who leads NASA's asteroid radar research program, said in a statement.
An asteroid, mind you, is made of metal and rock. A comet is made of rocky materials, dust, and ice. When comets come super close to Earth, they're also super close to the sun — and that makes their icy bits send gases off into space. Scientists love taking a look at off-gassing comets, because their ice is thought to contain some of the oldest, most pristine chemical traces of our early solar system.
2015 TB145 is expected to have a magnitude of around 10 when it approaches, so it could potentially be seen with an amateur telescope. Those in the Northern Hemisphere will have the best luck catching it.
This post has been updated.