Moons of our Solar System
Moons of our Solar System

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

Moons of our Solar System

1.1 Past volcanism on the Moon

Described image
Figure 7 This image was taken from Apollo 17 in lunar orbit and shows a smooth lunar mare on the left and more rugged and cratered older lunar highlands on the right.

A geologically active surface can mean many things, but for many planetary geologists it means volcanoes. For volcanoes to form, an eruptible magma is required. This means an internal melting mechanism such as heating is necessary for the production of the magma below ground, which can then rise towards the surface. The addition of gas aids the rise of magma and helps to make eruptions explosive, explaining the difference between a jet of magma shooting skywards and a gentle flow of lava onto the surface.

Evidence of volcanic flows on the Moon can be seen as smooth plains overlying older, more cratered surfaces. However, our Moon has not been majorly active for a long time. Most lunar maria were flooded by lava about 3 billion years ago, and the most recent volcanic activity on the Moon seems to have been more than a billion years ago. Since then, the Moon has gradually frozen solid and is no longer capable of producing magma, as the radioactivity keeping the deep mantle and core hot has diminished. How then, is it possible that volcanism on other moons still occurs? Io is the most volcanically active body in the Solar System, yet it is only marginally larger than our own Moon.


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, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 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 prospectus