Tau1 Gruis, the star that the newly discovered exoplanet orbits around.
Courtesy of NASA/JPL

More than 100 planets orbit distant stars!
News story originally written on September 25, 2002

Astronomers have identified another exoplanet, that is, a planet outside our solar system. This makes a total of 102 exoplanets that have so far been found by astronomers!

The astronomers that identified this exoplanet, have been searching outside our solar system for planets that are similar to Earth. They have been using the Anglo-Australian Telescope in New South Wales, Australia to search the southern skies. The planet they found is circling the star Tau1 Gruis and is three times as far from its star as Earth is from the Sun. The newly discovered planet has a mass similar to Jupiterís and is about 100 light years away.

The solar system of this newly discovered planet is organized a bit like ours. The planets are strung out in a line from the star, with the larger ones furthest away. Now that researchers have found so many exoplanets, they can see patterns that suggest that solar systems like ours, with the high-mass planets orbiting much further out are more common than those whose high mass planets are clustered close to the star.

How do astronomers find exoplanets? They look for stars that appear to wobble because of the gravitational pull of orbiting planets. The wobble can be detected by a Doppler shift in the starís light indicating the presence of a planet. This is then fine tuned to assess the planetís distance from the star and mass.

After astronomers have a good idea which of the exoplanets are like Earth, their next step is to look for evidence of life by analyzing the chemistry of the planet and its atmosphere for molecules of carbon, carbon dioxide, and ozone. Perhaps they will someday find evidence that we are not alone in the universe!

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