Mars Has a Heart, Too

Conspiracy theorists often point to the infamous Face on Mars when citing NASA's supposed propensity to cover up the nearby presence of aliens.

But aliens would have to have a heart, too, wouldn't they? If so, one may have been spotted in this 1999 Mars Global Surveyor image.

Researchers say the heart is no alien creation, however. Instead it is no more than a pit, a collapsed region of the surface technically known as a "graben." It formed along a fault line when the bedrock moved around. The depression is about 1.4 miles (2.3 kilometers) wide.

NEXT: A Pair of Hearts!