Stickney Crater on Phobos. Source
This strange looking crater is a prominent feature of the moon Phobos orbiting Mars. It was named after Chloe Angeline Stickney Hall, herself a mathematician and wife of the astronomer who discovered both Mars moons. This crater measures more than 9 kilometers across, nearly half the diameter of the entire moon.
Barnard's Loop and NGC 2170. Source
I thought that both of these pictures were cool enough to be pictures of the day, so I decided to display both. This beautiful mosaic spans 6 degrees in the night sky and highlights Barnard's Loop on the left, and NGC 2170 on the right. Barnard's Loop was shaped by a super nova long ago, but it is still a beautiful sight to behold. In the background we can see the star scape of the Milky Way galaxy.