See also:

The PLANET Consortium

Detecting Terrestrial Planets

The Ages of Terrestrial Planets

External Links:

AAT Finds New Planets (press release)

Extrasolar Planet Search (UC Berkeley)

Extrasolar Planets Encyclopaedia

Giant Planets Orbiting Faraway Stars (Scientific American)

Significant Others (Scientific American)

The Anglo-Australian Planet Search

The Anglo-Australian Planet Search project uses the 3.9m Anglo-Australian Telescope at Siding Spring to search for planets by the radial velocity method. As a planet orbits a star it causes a slight wobble in the motion of the star. This can be detected by sensitive measurements of the Doppler shift of the spectral lines of the star. About 50 extra-solar planets have now been detected in this way, mostly by northern hemisphere observatories. The Anglo-Australian Planet Search extends this survey to southern hemisphere stars and has recently found new planets orbiting the stars HD179949, Mu Arae and Epsilon Reticuli.

Radial velocity variations of the star Mu Arae measured with the Anglo-Australian Telescope reveal the presence of a planet with a mass of at least 1.86 times that of Jupiter orbiting with a period of 743 days.

One of the new planets found by the AAT orbits its star, Epsilon Reticuli, at a distance similar to that of the Earth, in the so called "habitable zone" in which liquid water could exist. While the planet itself, being a gas giant, is not a likely location for life, a moon orbiting the planet could well have suitable conditions.

This method detects giant planets of masses similar to or greater than those of Jupiter and Saturn in our own solar system. The wobble produced by a planet like the Earth is too small to be seen in this way. The new solar systems revealed by this work are often very different to our own. The giant planets in our solar system orbit far from the sun with long period orbits (12 years for Jupiter). Many of the new extrasolar planets are very close to their stars with orbital periods of only a few days. The close orbiting giant planets are known as 'Hot Jupiters'.

Such findings raise the question as to just how typical our own solar system is. Are there many solar systems like ours waiting to be discovered, or does our solar system have an unusual configuration which might have favoured the development of life? Continued observations should begin to answer this question as we should be able to find other cases of giant planets in similar orbits to Jupiter.