September 15th, 2012
A partial eclipse of the Sun by Phobos, as seen by the Mars Curiosity rover.
Not the most spectacular astronomical image you'll ever see, and not even all that rare an event,1 but even so it's pretty cool that we have a one ton, nuclear powered robot present on the Martian surface to beam the picture back to Earth.
- Phobos orbits Mars every 7 hours and 39 minutes, so there are frequent opportunities for it to get between the Sun and some point on the Martian surface. ↩