Kepler-188 and Its Two Planets

Kepler-188 is a star located 3160 light-years away. It is 4.37 billion years old, has 0.98 solar masses, 0.96 solar radii, and a temperature of 5730 K. Two planets are known to orbit it, both found by the transit method in 2014.

Kepler-188 b is a Super-Earth with a radius of 1.68 Earth radii, orbiting every 2.06 days. That is the shortest orbital period among the listed planets. Kepler-188 c is a Neptune-like planet with a radius of 3.19 Earth radii, orbiting every 6 days - the longest period among the listed planets. Its radius is also the largest among them.

Both planets were detected as they crossed in front of their star from our viewpoint, dimming its light slightly; repeated dips of this kind establish orbital periods. Size classes such as Super-Earth and Neptune-like describe radius relative to Earth's, not composition.