Kepler-187 and Its Two Known Planets

Kepler-187 is a star located 3730 light-years from Earth. It hosts two known planets. The star is 3.72 billion years old, with a mass of 1.11 solar masses and a radius of 1.2 solar radii. Its temperature is 6110 K, and both its mass and radius estimates are larger than the Sun's, while its reported temperature is hotter than the Sun's.

The two planets, Kepler-187 b and Kepler-187 c, were both discovered by transit in 2014. A transit occurs when a planet passes in front of its star from our viewpoint, causing a small dip in observed brightness; repeated dips help establish orbital periods. Kepler-187 b is an Earth-like planet with an orbital period of 4.94 days and a radius of 1.41 Earth radii, larger than Earth's. Kepler-187 c is a Neptune-like planet with an orbital period of 10.6 days and a radius of 2.67 Earth radii, also larger than Earth's. Among the listed planets, Kepler-187 b has the shortest year by reported estimates, while Kepler-187 c has the longest. Kepler-187 b also has the smallest radius by reported estimates, and Kepler-187 c has the largest.