Characterizing  Exoplanets

Once exoplanets have been discovered, they can be analyzed and characterized to determine their planet type and atmospheric composition. Planets are often grouped according to size, and whether or not they lie in the Habitable Zone and can thus support liquid water. Atmospheres are analyzed for the presence of biological markers (or biosignatures) which may indicate the presence of life.

A benefit to astronomers in researching exoplanets is that there is already a lot of information that has already been discovered from the stellar objects found here in our Solar System. In this sense, unlike in many other areas of research in the field of astronomy, scientists already have an starting point.

Exoplanets were first discovered in the 1990's by the radial velocity method. The above image depicts a few exoplanets discovered by the Kepler Telescope and their relative size to Earth (RE).


The smallest Earth-like planet found outside of our Solar System is called Kepler-10b (left) and lies 560 light years away. It is a mere 1.4 times the size of Earth and 4.6 times its mass.




The largest exoplanet discovered is called TrES-4. It is part of a subclass of exoplanets known as 'puffy planets' because its mean density is so low (only 0.2 g/cm3), and it is approximately 1.7 times larger than Jupiter (shown to the right).

Information about the types of exoplanets, exoplanet atmospheres, the habitable zone and biosignatures can be found in the following sections:

Exoplanet Types

Exoplanet Atmospheres

The Habitable Zone