Kepler-21 b
A confirmed exoplanet orbiting Kepler-21.
Compared with Earth
- Size
- About 1.6 times Earth's width.
- Mass
- About 7.5 times Earth's mass.
- Temperature
- About 1,742 °C (3,167 °F) from starlight alone, against -18 °C (-1 °F) for Earth measured the same way.
- Starlight
- About 2,749 times the starlight Earth gets from the Sun.
- Year
- A year here lasts about 2.8 Earth days.
Planet
- Radius
- 1.639 × Earth
- Mass
- 7.5 × Earth
- Density
- 9.3 g/cm³
- Equilibrium temperature
- 2,015 K
- Starlight received
- 2,749 × Earth
- Orbital period
- 2.786 days
- Average distance from its star
- 0.0434 AU
Star
- Host star
- Kepler-21
- Spectral class
- F — yellow-white
- Surface temperature
- 6,305 K
- Radius
- 1.902 × Sun
- Mass
- 1.408 × Sun
- Age
- 2.84 billion years
System
- Distance from Earth
- 354 light-years (108.5 parsecs)
- Stars in system
- 2
- Known planets
- 1
Discovery
- Year
- 2012
- Method
- Transit
- Facility
- Kepler
Data from the NASA Exoplanet Archive, synced October 14, 2026.