The large 2015 TB145 asteroid was discovered only on October 10, 2015 by the Pan-STARRS I survey.
And it will make a surprise flyby at an unusually high velocity on October 31, 2015.
As announced by NASA: […] 2015 TB145 was discovered on 2015 Oct 10 by the Pan-STARRS I survey.
This is the closest approach by a known object this large until 1999 AN10 approaches within 1 lunar distance in August 2027.
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 is 35 km/s, which is unusually high.[…]
This Halloween asteroid, most probably of cometary nature, should be one of the best radar targets of the year. So get you a telescope right now.