Mercury's Moons
Written by Fraser Cain
Mosaic of Mercury. Credit: NASA / JHUAPL / CIW / mosaic by Jason Perry
Most of the planets in the Solar System, but Mercury has no moons.
But for a little while astronomers did think it had a moon. Back in 1974, when NASA's Mariner 10 spacecraft was just about to make its flyby of the planet, astronomers detected a spike of ultraviolet radiation from the planet. They thought this spike of ultraviolet radiation might have come from radiation reflected off of Mercury's moons. But when Mariner 10 arrived at Mercury, it found no moons, and astronomers realized that the flood of ultraviolet must have come from a more distant star that happened to be lined up at the time.
Mercury's surface is heavily cratered, just like the Earth's moon. It's possible that it might have had moons billions of years ago, just like some planets have captured asteroids as moons. But any moons would have crashed to the surface long ago, joining the countless impact craters on the surface of Mercury.
We've written many articles about the moons for other planets in the Solar System. Here's an article about which planet in the Solar System has the most moons, and here's an article about asteroids with moons.
Want more information about Mercury's lack of moons? Here's NASA's short, sweet page on this, and here's a table of moons in the Solar System.
We've also recorded an entire episode of Astronomy Cast just about Mercury. Listen here, Episode 49: Mercury.
Filed under: Astronomy
Tags: Mercury, planet mercury, Solar System
