2009 BD
is a very small asteroid, approximately 10 meters in diameter, which is classified as near-Earth object of the Apollo group and as an Earth co-orbital asteroid. Orbit During the 2011 opposition, the last opposition of that was observed, approached on June 2, 2011 within 0.00231 AU (346,000 km) of the Earth, which is less than 1 lunar distance. For comparison, the distance to the Moon is about 0.0026 AU (384,400 km). With an orbital period of 369.99 days, is in a near 1:1 orbital resonance with Earth, and also has about the same orbit around the Sun as Earth. Other resonant near-Earth objects in addition to include (the first to be discovered), , , , , , , and (an Earth trojan). The Jupiter Tisserand invariant, used to distinguish different kinds of orbits, is 6.039. The orbit has a small inclination of about 0.4 degrees. JPL and MPC give different parameters for the orbit of , affecting whether the orbit type should be considered an Apollo asteroid or an Amor asteroid. JPL includes non-gravitational acceleration parameters in the orbital solution. Physical characteristics Because is a very small multi-opposition near-Earth object, the effect of radiation pressure on the orbit caused by