In Greek mythology, Gaia was the great Earth Mother, the creator and giver of birth to the Earth and all the Universe. Much more recently, James Lovelock put forward his Gaia hypothesis, which proposes that living organisms and inorganic material are part of a dynamic system that shapes the Earth’s biosphere, and maintains the Earth as a fit environment for life. Gaia is also the name of a particularly important space probe to be launched in the next few weeks by the European Space Agency. Its aim is to produce a three-dimensional map of our Milky Way Galaxy of 100,000,000,000 stars. It will study about 1% of these, building up a picture of each star’s brightness, colour, distance, chemical composition and speed and direction of motion.
For stars within a distance of approximately 150 light-years from the Sun, Gaia is also expected to find every Jupiter-sized planet with an orbital period of 1.5 – 9 years. It will do this by watching out for tiny wobbles in the star’s position. This behaviour is caused when a star is tugged by the gravitational pull of a planet in orbit around it.
In our own Solar System Jupiter, and to a lesser extent all the other planets, do this to the Sun, making it wobble. Estimates suggest that Gaia will detect between 10,000 and 50,000 planets beyond our Solar System. At the end of its 5 year mission, we shall know a great deal more about our Galaxy and its evolution over the last few billion years than we do now.
The Torbay Astronomical Society will have its next meeting on Thursday 10 October. Our speaker will be Richard Cole, who originally came from Torbay, and who now works at the Mullard Space Science Laboratory, near Guildford. His topic will be The Dark Side of the Universe: The Euclid Mission. Then on Thursday, October 24, our observational evening will be focussing on M31, the planet Uranus, and the star Gamma Andromedae.
All meetings are held at Torquay Boys’ Grammar School, Shiphay Manor Drive, from 7.30pm until 10pm. The lecture meetings are in their Business & Enterprise Suite, and observational evenings start out in the Physics Lab PL4. Visitors and new members are very welcome. Membership for the year is £15 (only £10 for 65s and over), and visitors are charged £3 for lectures and £2 for observational evenings.
The society has a new website at http://www.torbayastro.org.uk and this gives full details of all our activities.