Moons of our Solar System
Moons of our Solar System

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

Moons of our Solar System

1.2 Present volcanism on other moons

Described image
Figure 8 Io, caught in the act. 200-km-wide false-colour image taken by NASA’s Galileo spacecraft shows an incandescent lava flow at the Tvashtar volcano.

We know several moons in the Solar System to be volcanically active and see evidence in the form of recognisable surface deposits and by imaging of eruptions in progress.

What is driving Io?

Timing: Allow approximately 10 minutes.

Earth’s Moon froze long ago. What heat source could possibly be driving Io’s continuing volcanism, such as the eruption producing the plume visible on the left of this image, which is rising more than 100 km above the surface? Think back to the ‘Tidal heating explained’ video near the end of the first week.

Described image
Figure 9 Voyager 1 image of Io showing an active plume from Loki volcano rising above the limb.


Described image
Figure 10 Io image captured by Galileo in 1997.

Thanks to orbital resonance with Europa, the varying tidal forces on Io caused by the eccentricity of its orbit around Jupiter are so strong that Io’s tidal bulges are expected to rise and fall by up to 100 m during a single orbit, and also migrate to and fro a little. This distortion generates an immense amount of heat, fuelling the most volcanic body in the Solar System.


Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371