Kepler-42 is a star with 0.13 times the mass of the Sun, and 0.17 times its radius. It is located 130.66 light years away from the solar system and is estimated to be 4.5 billion years old, as compared to the Sun which is roughly 4.6 billion years old.

Kepler-42 is known to have 3 exoplanets in orbit around it.

Kepler-42 b was discovered by the Kepler observatory, in 2012-03, using the transit method. Its semi-major axis is 0.01 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of Kepler-42 b is 0.401 times the mass of Earth. The radius of Kepler-42 b is 0.780 that of Earth. At less than 1.5 Earth masses, Kepler-42 b is a regular terrestrial planet, much like the terrestrial planets we find in our solar system, namely Mercury, Venus, Earth and Mars.

Kepler-42 c was discovered by the Kepler observatory, in 2012-03, using the transit method. Its semi-major axis is 0.01 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of Kepler-42 c is 0.315 times the mass of Earth. The radius of Kepler-42 c is 0.730 that of Earth. At less than 1.5 Earth masses, Kepler-42 c is a regular terrestrial planet, much like the terrestrial planets we find in our solar system, namely Mercury, Venus, Earth and Mars.

Kepler-42 d was discovered by the Kepler observatory, in 2012-03, using the transit method. Its semi-major axis is 0.02 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of Kepler-42 d is 0.130 times the mass of Earth. The radius of Kepler-42 d is 0.570 that of Earth. At less than 1.5 Earth masses, Kepler-42 d is a regular terrestrial planet, much like the terrestrial planets we find in our solar system, namely Mercury, Venus, Earth and Mars.