満月
The other major detection bias is that it is much easier to spot objects on the night-side of Earth. The day sky near the Sun is much brighter than the night sky, and there is therefore much better contrast in the night sky. The night-side searcher is also looking at the sunlit side of the asteroids, while in the daytime sky a searcher looks towards the sun and sees the unlit backside of the object. In addition, opposition surge makes asteroids even brighter when the Earth is close to the axis of sunlight. The combined effect is equivalent to the comparison of a Full moon at night to a New Moon in daytime, and the light of the Sun-lit asteroids has been called "full asteroid" similar to a "full moon".