This striking image shows the progression of daylight across the surface of Mercury. This line separating night from day is called the terminator. Scientists have studied interesting phenomena occurring near the terminator of the Moon for years. Such occurrences involve the interaction between lunar dust and charged solar particles. Because Mercury's regolith is exposed to almost ten times as many charged particles as the Moon, it is an excellent place to study the effects of solar radiation on surface materials. In this unprojected image, north is to the right.
Date acquired: August 01, 2011
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington