The larger of the two moons of Mars, Phobos, passes directly in front of the other, Deimos, in a new series of sky-watching images from NASA's Mars rover Curiosity.
By tradition, the moons of Pluto have names associated with Hades and the underworld. But there's plenty of possibilities to choose from - and the discoverers of the planet's two tiniest moons are inviting the public to name them.
Two professors say that the unusual moons of Saturn could be explained by several large impacts in which several major satellites merged to form Titan.
NASA's New Horizons spacecraft - now just two years away from Pluto - is on a riskier mission than previously realized, thanks to the threat posed bty the planet's moons and possible rings.
NASA has released a number of new images of Saturn and Titan snapped by the agency’s Cassini spacecraft.
Uranus was knocked on its side not by a single massive collision, as previously thought, but by a series of small thumps, researchers say.