Space Facts

Kepler-20e and Kepler-20f
Two Earth-sized Planets

Earthdate: 2011:1220

An artist's concept of planet Kepler-20e, a world slightly smaller than Earth. Image Credit: NASA/Ames/JPL-Caltech

Five planets have been discovered in the Kepler-20 system. Two of them are close to the same size as Earth. Regrettably, neither of them are in the "Goldilocks zone"—that "just right" location where the warmth from their sun could allow for liquid water. Instead, both of these planets of Earth-like size are super heated, up close to their parent star.

The star, Kepler-20, is similar to our own sun, but slightly dimmer, cooler and smaller. Better than Kepler-22, this star has a metallicity very similar to that of our own sun, and slightly richer. This means that these planets likely have a chemistry similar to the terrestrial worlds in the Solar System.

An artist's concept of planet Kepler-20f, a world slightly larger than Earth. Image Credit: NASA/Ames/JPL-Caltech

System Parameters:
Name: Kepler-20
Apparent Magnitude: 12.498
Distance: 950 light years (290 parsecs)

Star:
Mass: 0.912 ☉
Radius: 0.944 ☉
Fe/H: +0.02

Planet: Kepler-20e
Discovered: 2011
Mass: <0.005 M_J (0.39–1.67 M_Earth)
Radii: 0.077 R_J (0.868 R_Earth)
Semi-major Axis: 0.0507 AU
Orbital Period: 6.098493 days
Eccentricity: <0.28
Inclination: 87.50 degrees
Effective Temperature: 1040K

Planet: Kepler-20f
Discovered: 2011
Mass: <0.010 M_J (0.66–3.04 M_Earth)
Radii: 0.092 R_J (1.034 R_Earth)
Semi-major Axis: 0.1104 AU
Orbital Period: 19.57706 days
Eccentricity: <0.32
Inclination: 88.68 degrees
Effective Temperature: 705K

References:
http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=172
http://exoplanet.eu/catalog-transit.php