Mercury's surface looks similar to our Moon's. Each is heavily cratered and made of rock. Mercury's diameter is about 4800 km, while the Moon's is slightly less at about 3500 km (compared with about 12,700 km for the Earth). But Mercury is unique in many ways. Mercury is the closest planet to the Sun, orbiting at about 1/3 the radius of the Earth's orbit. As Mercury slowly rotates, its surface temperature varies from an unbearably cold -180 degrees Celsius to an unbearably hot 400 degrees Celsius. The place nearest the Sun in Mercury's orbit changes slightly each orbit - a fact used by Albert Einstein to help verify the correctness of his then newly discovered theory of gravity: General Relativity. The above picture was taken by the only sp ...

This is the first image taken by NASA’s Curiosity rover of what Earth looks like from its station on Mars. Not one to let a golden social media moment go to waste, Curiosity promptly tweeted: “Look Back in Wonder… My first picture of Earth from the surface of Mars."

The strangest moon in the Solar System is bright yellow. Taken by the Galileo spacecraft, this image shows Jupiter's moon, Io, and its incredibly bright colours derived from sulphur and molten silicate rock. Io is covered in volcanoes that are so active, they effectively turn the whole moon inside out. And some of Io's volcanic lava is so hot, it glows in the dark.

Scientists identified sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon -- some of the key chemical ingredients for life -- in the powder Curiosity drilled out of a sedimentary rock near an ancient stream bed in Gale Crater on the Red Planet last month.