New photos of Mercury's mysterious north pole reveal a ... during the day, according to NASA. But the planet lacks an atmosphere to hold that heat in — so, on Mercury, dark equals cold.

This composite image of the Sun combines high-energy X-ray data from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR). On December 6, 2010, a lengthy solar filament, which had been winding around ...

Though Mercury may look drab to the human eye, different minerals appear in a rainbow of colors in this image from NASA's MESSENGER spacecraft. This visual may only be used in conjunction of ...