Binary asteroid - HD 影片檔

"Fly-by of a high mass ratio binary asteroid. Numerous asteroids have been found to have smaller bodies orbiting them. The asteroids are small chunks of planetary debris largely found between the orbits of Mars and Jupiter. There are many millions of asteroids, most very small. The largest, Ceres, has a diameter of 975 kilometres, and makes up 21% of the entire mass of the belt."