Kepler-20

Kepler-20 is a star about from Earth in the constellation Lyra with a system of at least five, and possibly six, known planets. The apparent magnitude of this star is 12.51, so it cannot be seen with the unaided eye. Viewing it requires a telescope with an aperture of or more. It is slightly smaller than the Sun, with 94% of the Sun's radius and about 91% of the Sun's mass. The effective temperature of the photosphere is slightly cooler than that of the Sun at , giving it the characteristic yellow hue of a stellar class G8 star. The abundance of elements other than hydrogen or helium, what ast

Kepler-20f (also known by its Kepler Object of Interest designation KOI-070.05) is an exoplanet orbiting the Sun-like star Kepler-20, the second outermost of five such planets discovered by NASA's Kepler spacecraft. It is located approximately 929 light-years (285 parsecs, or about km) from Earth in the constellation Lyra. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. The planet is notable as it has the closest radius to Earth known so far.

Kepler-20e is an exoplanet orbiting Kepler-20. The planet is notable as it is the first planet with a smaller radius than Earth found orbiting a Sun-like star. The planet is second-closest to the star after Kepler-20b, and at , it is far too hot to have liquid water on its surface. Along with the other four planets in the system, Kepler-20e was announced on 20 December 2011.

Kepler-20b is an exoplanet orbiting Kepler-20 in a system 922 light years from Earth. It is classified as a Super-Earth, as it has a radius and mass greater than that of Earth. Its radius of about 1.87 would typically mean that it is a Mini-Neptune; but its high mass of 9.7 implies that it is an iron-rich rocky world. Along with the other four planets in the system, Kepler-20b was announced on 20 December 2011.

Kepler-20c is an exoplanet orbiting Kepler-20. It has a mass similar to Neptune but is slightly smaller. Despite being the third-closest planet to Kepler-20, it is still close to the star, meaning that it is a hot Neptune. Along with the other four planets in the system, Kepler-20c was announced on 20 December 2011.

Kepler-20d is an exoplanet orbiting Kepler-20. It has a mass and radius similar to Neptune. Despite being the furthest planet from the star, it has an orbit similar to Mercury, meaning that it is a hot Neptune. Along with the other four planets in the system, Kepler-20d was announced on December 20, 2011.

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