Interestingly, the asteroid had its own moon (about 240 feet in diameter) circling it.
The asteroid was named 2004 BL86, because it was first spotted back in 2004 (by an observatory in New Mexico).
CNN Reports:
It was far enough that it didn't pose a threat to Earth, but close enough to give scientists and amateurs a chance to observe a large asteroid up close.NASA asteroid 2004 BL86 was revealed to have its own small moon.
EXPAND IMAGE
It was the closest known asteroid this large to pass near Earth until 2027, when an asteroid called 1999 AN10 flies by.
Read more here:
http://www.cnn.com/2015/01/26/us/asteroid-flyby/index.html
