Most of the pictures used to illustrate all three components of the course come from spacecraft that have been sent to investigate the nearby planets and their satellites, because it is close-up images like these that give you the most straightforward impression of what it would be like to visit these places. I continue to be amazed whenever I see a picture of a rock-strewn landscape on Mars or an erupting volcano on Io (one of Jupiter’s largest satellites).

A 300 km wide view of part of Io, a large satellite of Jupiter, recorded by NASA’s Galileo orbiter in 1999. The red feature is a fissure from which red-hot molten lava was being erupted.

The first edition of my book was published in 2000, and preparing the revised edition for the course really brought home to me how fast our knowledge is expanding in many areas of planetary science. In particular, advances in the use of telescopes meant that in the intervening three years dozens more small moons were discovered in orbit around Jupiter, Saturn and Uranus. Over the same period, the number of known Pluto-like bodies in the so-called Kuiper Belt on the outer fringe of the Solar System quadrupled to nearly a thousand and the number of planets detected around other stars quadrupled to over a hundred.

Thus whether it is stunning close up pictures from spaceprobes that excite you, or clever use of telescopes to detect and study small and elusive objects, this is a great time to be interested in astronomy and planetary science. Advanced technology is serving us very well. New information is coming in all the time, and the best of it is readily available on the internet. Mind you, I still like staring at the night sky.

Further information about the Open University short course Planets: an introduction, can be found at http://www3.open.ac.uk/courses/bin/p12.dll?C02S196_science

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Content last updated: 05/08/2003