Kepler-30 and Its Three Planets

Kepler-30 is a star located 2980 light-years away, with three planets known to orbit it. The star is 1.58 billion years old and has a reported mass estimate of 0.95 solar masses, a reported radius estimate of 0.86 solar radii, and a temperature of 5450 K. Its reported mass and radius estimates are smaller than the Sun's, and its reported temperature is cooler than the Sun's.

The three planets are Kepler-30 b, Kepler-30 c, and Kepler-30 d. All were discovered by transit in 2012, a method in which a planet passes in front of its star from our viewpoint and causes a small dip in observed brightness; repeated dips help establish orbital periods, the time a planet takes to complete one orbit.

Kepler-30 b is Neptune-like, with a radius of 3.9 Earth radii and a mass of 11.3 Earth masses. Its orbital period is 29.3 days, and its mean density is 1.05 g/cm³, 0.19 times Earth's. Among the listed planets, it has the shortest year and the smallest radius and reported mass.

Kepler-30 c is Jupiter-like, with a radius of 12.3 Earth radii and a mass of 640 Earth masses, roughly 2.01 times Jupiter's mass. Its orbital period is 60.3 days, and its mean density is 1.9 g/cm³, 0.344 times Earth's. Among the listed planets, it has the second-shortest year and the largest radius and reported mass.

Kepler-30 d is Jupiter-like, with a radius of 8.8 Earth radii and a mass of 23.1 Earth masses. Its orbital period is 143 days, and its mean density is 0.187 g/cm³, 0.0339 times Earth's. Among the listed planets, it has the longest year and the second-smallest radius and reported mass.

Each planet's radius and mass estimates are larger than Earth's.