One week ago, the MESSENGER spacecraft transmitted to Earth the first high-resolution image of Mercury by a spacecraft in over 30 years since the three Mercury flybys of Mariner 10 in 1974 and 1975.

Mercury, the closest planet to the sun, is only slightly larger than Earth's moon and is pockmarked with craters. The planet is visible to the unaided eye and as such as has long been known to humans.

Mercury is a planet of extremes. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. The planet is named after the Roman deity Mercury, the speedy ...

The elusive planet Mercury reaches its furthest point from the sun on Friday (Jan. 12), with this separation allowing skywatchers a chance to spot the tiny planet. The fact that Mercury is the closest ...