Looking for a sky event this week? Check out our full Sky This Week column. January 11: Psyche moves north of Aldebaran Io ...

The moon spent a few million years as a volcanic wasteland, covered with ongoing eruptions that spewed from mountains and even from the ground itself. New research suggests that the moon's orbit could ...

Io orbits so close to Jupiter that gravity alone reshapes its entire surface. Instead of cooling over time, the moon is ...

Jupiter’s volcanic moon has always felt like a place that tests your sense of what a world can be. Its surface glows with hundreds of active hot spots. Its mountains rise higher than Everest. Its lava ...

Io is the fourth largest moon in the solar system, but it has the highest density thanks to its iron-sulfide core. It is the innermost Jovian moon, and its close proximity to the gas giant leads to ...

Although Europa is the fourth largest of Jupiter’s 95 moons, it’s the smallest of the Galilean moons – the largest being Ganymede. With an equatorial diameter of about 3,100 kilometres, Europa is ...