An exoplanet is a planet outside our solar system that usually orbits a star in our galaxy. More than 7,000 have been found in the Milky Way since the first confirmed discovery in the 1990s, and "billions more remain to be discovered", said Tech Explorist.

Astronomers have found some pretty wild exoplanets. Some are balls of lava the temperature of hell, one is partially made of diamond, and another may rain molten iron. However, not all exoplanets are this extreme.

HD 20794 d completes its orbit just shy of two Earth years, placing it well within reach of conditions that might harbor life.