This is the beginning of a series of posts on extrasolar planets. References and further readings are indicated by [number] and can be found at the bottom of the page under “References”.
What is an extrasolar planet?
An extrasolar planet (or exoplanet) is a planet that orbits a star other than our Sun. This leads us to the question “What is a planet?”. The International Astronomical Union (IAU) has come to the following definition of planets in our Solar System :
A planet is a celestial body that
(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
(c) has cleared the neighbourhood around its orbit.
TO BE CONTINUED!