Exoplanets

An exoplanet is a planet that is found outside of the solar system.  Exoplanets are also referred to as extrasolar planets.

Astronomers use many different techniques to locate these planets. Astronomers have discovered 843 exoplanets, 663 are in single planetary systems and there are 126 exoplanets in multiple planetary systems. Astronomers have predicted that there are above a billion exoplanets in the Milky Way galaxy.

Below is an example of an exoplanet orbiting in a binary star system:

To discover exoplanets astronomers use three techniques. The first technique involves using precise radial velocities, and this technique is the most commonly used. The second technique is the transit method, and the third is imaging.  Imaging is the hardest method of discovering exoplanets used be astronomers.


Here is a picture of some of the discovered exoplanets compared to their companion stars: