Kepler-122 and Its Five Planets

Kepler-122 is a star located 3350 light-years away, and five planets have been identified in orbit around it. The star is 3.89 billion years old and has a reported mass of 1.08 solar masses, a radius of 1.15 solar radii, and a temperature of 6080 K. Its mass, radius, and temperature are each reported as larger than the Sun's.

The five planets were all discovered by transit, the method in which a planet passes in front of its star from our viewpoint and causes a small dip in observed brightness. All five were reported in 2014.

Kepler-122 b, a Super-Earth with a radius of 2.34 Earth radii, orbits in 5.77 days. Kepler-122 c, a Jupiter-like planet with a radius of 5.87 Earth radii, orbits in 12.5 days. Kepler-122 d, a Super-Earth with a radius of 2.2 Earth radii, orbits in 21.6 days. Kepler-122 e, a Neptune-like planet with a radius of 2.6 Earth radii, orbits in 38 days. Kepler-122 f, a Super-Earth with a radius of 1.75 Earth radii and a mass of 36 Earth masses, orbits in 56.3 days. Every planet's reported radius is larger than Earth's, and Kepler-122 f's reported mass is larger than Earth's as well. Its mean density is 37 g/cm³, 6.72 times Earth's.

Among the listed planets, Kepler-122 b has the shortest year, at 5.77 days, and Kepler-122 f has the longest, at 56.3 days. Kepler-122 c has the second-shortest year, at 12.5 days, while Kepler-122 e has the second-longest, at 38 days. In radius, Kepler-122 f is the smallest at 1.75 Earth radii, and Kepler-122 c is the largest at 5.87 Earth radii. Kepler-122 d has the second-smallest radius at 2.2 Earth radii, and Kepler-122 e has the second-largest at 2.6 Earth radii.