Extrasolar Planets - Research Article from Macmillan Science Library: Space Sciences

This encyclopedia article consists of approximately 4 pages of information about Extrasolar Planets.
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Method of Detection

The planets of the solar system are visible because of the sunlight that they reflect. Unfortunately, planets that orbit other stars are far too faint relative to their stars for current astronomical telescopes to observe them directly as faint points of light next to their much brighter stars. Instead, astronomers use a variety of techniques to indirectly infer the presence of these extrasolar planets.

The method by which all of the known extrasolar planets have been discovered is the radial velocity (or Doppler) technique. The mass of the orbiting planet causes the central star to be pulled around in an orbit. Astronomers detect the resulting small, periodic shifts in the apparent speed of the star. By measuring the shape of the resulting Doppler curve over time, they are able to deduce a lower limit on the mass of the planet and estimate the separation of...

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This section contains 1,153 words
(approx. 4 pages at 300 words per page)
Buy the Extrasolar Planets Encyclopedia Article
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Macmillan Science Library: Space Sciences
Extrasolar Planets from Macmillan Science Library: Space Sciences. Copyright © 2001-2006 by Macmillan Reference USA, an imprint of the Gale Group. All rights reserved.
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