A global colour mosaic of the part of Triton imaged by Voyager 2 in 1989.  The south polar cap is at the bottom and the cantaloupe terrain north of it. (Source: NASA/JPL/USGS)

Triton – a mysterious encounter

In 1989, Voyager 2 approached Triton, by far Neptune’s largest moon. We already knew it was very cold, near the freezing point of nitrogen, and there were great hopes of finding a world such as Titan turned out to be,…

A trio of false colour images combining visible and infrared images taken by three Cassini flybys of Titan (Source: NASA/JPL/University of Arizona)

Titan – land of lakes and valleys

When it comes to Saturn’s largest moon, the question is not ‘what’s cool about Titan?’, it’s what’s *not* cool about it. It’s like a planet out of sci-fi: a land of mountains and valleys, lakes and rivers, hazy skies and…

False colour mosaic image of Enceladus taken by Cassini. The tiger stripes are seen at the bottom. (Source: NASA/JPL/Space Science Institute)

Enceladus – Brave New World

Enceladus is one of the jewels of recent planetary exploration: a highly active and potentially life-bearing moon where we least expected it. It’s Saturn’s seventh moon and though it’s far from the heat of the Sun, it has enough internal…

Callisto as seen by Voyager II. Bright areas are the most recent impact craters, but the majority is dark due to rock mixed with the ice. (Source: NASA)

Callisto – Ancient World

A journey past the major (Galilean) moons of Jupiter from the inside out is also a journey from intense activity to virtual quiescence, and from full internal differentiation into metal, rock and volatiles to a much more homogeneous mix. So…

Ganymede gobal natural colour image (Source: NASA)

Ganymede – ice giant

Ganymede is next out from Jupiter after Europa and it’s an icy behemoth: larger than any other moon in the Solar System, larger even than Mercury.  ESA are gearing up to send JUICE (the Jupiter Icy Moon Explorer) out to the…

Global View of Europa - natural colour (Source: NASA)

Europa – what lies beneath

Travel one moon further out from Io and you’ll go from fire to ice: Europa.  All of the moons of the Solar System beyond Io are icy, but Europa is special: its frozen layer may be comparatively thin, and beneath…