Asteroid That Flew Past Earth Has Moon

Other binary and even triple systems out there.
The first radar images from Deep Space Network in California of asteroid 2004 BL86 show the asteroid, which made its closest approach on Jan. 26, 2015 at 8:19 a.m. PST (11:19 a.m. EST) at a distance of 3.1 times the distance from Earth to the moon has its own small moon.

Images show the primary body is approximately 1,100 feet (325 meters) across and has a small moon approximately 230 feet (70 meters) across. In the near-Earth population, about 16 percent of asteroids that are about 655 feet (200 meters) or larger are a binary (the primary asteroid with a smaller asteroid moon orbiting it) or even triple systems (two moons).

Monday’s flyby is the closest a known asteroid this size will come to Earth until 2027.