Astronomy Picture of the Day

Explanation: Hard to spot against the twilight glow near planet Earth's horizon, a crescent Mercury was imaged close up by the MESSENGER spacecraft early last week. Colours in this remarkable picture were created using data recorded through infrared, red, and violet filters. The combination enhances colour differences otherwise not visible to the eye across the innermost planet's cratered surface. In this view, light bluish material seems to surround relatively new craters, contrasting with the mostly drab, brown terrain. Mercury itself is 4,880 kilometres in diameter. The full resolution image shows features as small as 10 kilometres across.