Kepler-142 and Its Three Known Planets

Kepler-142 is a star located 1,790 light-years away, and three planets have been detected in its orbit: Kepler-142 b, Kepler-142 c, and Kepler-142 d. The host star is 5.5 billion years old, with a mass of 1.06 solar masses and a radius of 1.18 solar radii. Its temperature is 5870 K. Each of these reported values exceeds the corresponding value for the Sun: the star is more massive, larger, and hotter than our own.

All three planets were discovered in 2014 using the transit method, in which a planet passing in front of its star dims the observed light slightly. Repeated dips of this kind reveal a planet's orbital period, the time it takes to complete one orbit.

Kepler-142 b is a Super-Earth with a radius of 1.99 Earth radii and an orbital period of 2.02 days. That radius is larger than Earth's, and among the listed planets it is the smallest. Kepler-142 c is a Neptune-like planet with a radius of 2.86 Earth radii and an orbital period of 4.76 days. Its radius is also larger than Earth's and is the largest among the listed planets, and its orbital period is the second-shortest. Kepler-142 d is a Super-Earth with a radius of 2.16 Earth radii and an orbital period of 41.8 days. Its radius is likewise larger than Earth's and is the second-smallest among the listed planets, while its orbital period is the longest of the three.

The size classes reflect radius rather than composition. A Super-Earth can reach 2.5 times Earth's radius, while a Neptune-like planet can reach 4 times Earth's radius, so all three planets fall within those respective size ranges.