This beautiful heart is located nearly on the equator of Mars, and is about 2 km (1.2 miles) long. The picture was taken by the Mars Reconnaissance Orbiter.

Like most valentine-shaped features on Mars, this is a collapsed pit - you can see the ripple of sand dunes in the upper right part of the heart. It may have formed when water just under the surface was catastrophically released as a huge flash flood, causing the surface above it to slump... and given the shape of the pit, I'll try to avoid any "tears of joy" analogy.

Higher res version.
Original release.

Image Credit: NASA/JPL/Malin Space Science Systems