Discovery of Exoplanet systems part 1

There are several methods used to detect exoplanet systems. These methods are both indirect and direct. When referring to a direct method, this means that we can view the exoplanet directly. On the other hand, while referring to an indirect method, this means we cannot observe the exoplanet directly.  It means we infer that the planet is there based on shadows, the speeds of objects around it, and the apparent brightness of the companion star. The indirect methods of exoplanet detection include; the radial velocity method,  and the transit method.  The direct method used to detect exoplanets is direct imaging.


The radial velocity method uses a star's orbital response to a planet with respect to the Earth.  A star that has a planet will move a little bit in its orbit as a response to the planet's gravity.  The orbital change leads to a variation in speed of the star with respect to the Earth.  The speed the star moves toward or away from the Earth would change. The star's spectral lines will be displaced when looking from Earth due to the Doppler effect (http://michastrostudent.blogspot.com/2013/02/doppler-effect.html).  These variations are used to confirm the presence of an exoplanet.

to be continued....