Radar images from those observations revealed asteroid 2015 TB145 true size (it's a bit larger than previously thought) and its speed. The asteroid is hurtling through space at a whopping 78,293 mph (126,000 km/h).
"This would generate a 6-mile-wide crater if it were to the Earth, something of this size and speed," asteroid impact expert Mark Boslough, a physicist at Sandia National Laboratories in New Mexico, said in the Slooh webcast. He was also impressed by the early radar images of the 2015 TB145.And it was only found a few weeks before its close fly by. Link.