Extrasolar Planets & Exoplanets
- Canadians S. Yang, G.A.H. Walker and Bruce Campbell were the first astronomers who proposed the existence of exoplanets in 1988. They studied the Gamma Chepei star and used radial velocity to detect an exosplanet moving around it. In 1992, Aleksander Wolszczan announced another set of planets discovered from a different star.
The first actual exoplanet discovered orbiting a star like our sun is 51 Pegasi b. This planet resembles Jupiter and was discovered by Didier Queloz and Michel Mayor in 1995. Since then, through the advancements in technology, many other exoplanets have been discovered.
- Because planets orbit around a star, the brightness of the star prohibits even the most powerful telescopes from detecting rotating planets. One way astronomers discover an exoplanet is when a star's brightness dims temporarily. When this happens, astronomers theorize that a large astronomical body is blocking the star's light.
Another process detecting exoplanets studies the characteristics of stars. A star without any planet revolving around it has a steady and almost perfect movement. On the other hand, stars that have planets revolving around them tend to wobble in a certain direction. This wobbling is the result of another astronomical body's gravity tugging at the star. Although stars are very large, a planet's gravity can still affect its movement. Using radio telescopes is another way to detect exoplanets; radio telescopes detect radio waves of hot gases and dust particles that form during the creation of a solar system.
- Most discovered exoplanets resemble Jupiter, although the majority are far larger. Planets like Jupiter are made up of gas and have very violent weather conditions.
Detecting large planets is also easier when compared to planets like Earth, although some exoplanets the size of the Earth have also been discovered. Most of these smaller exoplanets resemble Mars and Venus, which have dry surfaces made up of rock. Most exoplanets discovered orbit nearer the star they are revolving around when compared to Earth, likely due to it being easier to discover planets rotating closely around the star.
- Several projects are attempting to discover and learn more about exoplanets. A project proposed by the European Space Agency in 1993, known as the "Darwin Project," aims to launch four to five satellites into space to specifically look for exoplanets that might have some resemblance to Earth. The Darwin project was put on hold in 2007 because scientists were not sure if current technology is good enough to make the satellites work as desired.