NASA discovers 2 exoplanets the size of Earth

William Atkins
Wednesday, 21 December 2011 23:42

Science - Space

The NASA Kepler Space Telescope has found two Earth-sized planets that orbit around a Sun-like star. What makes the discovery so important is that these two extrasolar planets are the first ones to be discovered that are approximately the size of Earth.

These two extrasolar planets (exoplanets) are named Kepler-20e and Kepler-20f. They are in a five-planet solar system, at about a distance of 950 light-years away from Earth and located in the constellation Lyra.

The other three planets (Kepler-20b, Kepler-20c, and Kepler-20d) in the system are much larger bodies, about the size of the planet Neptune.

All five planets orbit very closely to its parent star - relatively, closer than the orbit of Mercury around the Sun.

Even though that are Earth-sized planets, both 'e' and 'f' reside outside the habitable zone (what is sometimes called the Goldilock zone) where liquid water could exist on the planets' surfaces

Specifically, Kepler-20e makes one orbit around its parent star in 6.1 days, while Kepler-20f takes a little longer, at 19.6 days.

Consequently, both planets are extremely hot with an average temperature on Kepler-20e at 800 degrees Fahrenheit (about 426 degrees Celsius) and on Kepler-20f at about 1,400 degrees Fahrenheit (760 degrees Celsius).

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