One week ago, the MESSENGER spacecraft transmitted to Earth the first high-resolution image of Mercury by a spacecraft in over 30 years since the three Mercury flybys of Mariner 10 in 1974 and 1975.

Mercury may have comet dust to thank for its dark appearance. The smallest planet in the solar system (sorry Pluto) has curious coloring: It’s darker than it should be, and scientists aren’t sure why.

View of planet Mercury from space. Space, nebula and planet Mercury. This image elements furnished by NASA. A few evenings ago I found myself in a remote layby in Utah close to Canyonlands National ...

Mercury will retrograde from Dec. 13 through Jan. 2 in the last of four times it appears to move backward in the sky this year. Every planet has in our solar system has retrograded for at least part ...