Kepler-20e and Kepler-20f, two new Earth-like planets, discovered

NASA scientists announced the discovery of two Earth-sized planets, Kepler-20e and Kepler-20f, today.

The planets, which were discovered by the Kepler space telescope team, are believed to be too close to their sun for them to be habitable.

However, according to CNN, scientists speculate that Kepler-20f, one of the planets, may have had liquid water at one time in its history and may have been habitable then. 

According to the Kepler science team, this is the first time humanity has been able to detect planets of Earth's size in the universe.

The two planets are orbiting a star called Kepler-20, which is almost 1,000 light years away. 

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According to the Houston Chronicle, Kepler-20 is a G-type star and is slightly cooler than the sun.

According to the Washington Post, Kepler-20 is much like our sun, but the planets orbit around it so fast and so close that their surfaces sizzle. 

It would take the fastest spacecraft more than 4,000,000 years to reach the new planets from Earth, the Guardian reported.

According to Dr. Francois Fressin of the Harvard-Smithsonian Center for Astrophysics, one of the planets is the closest object to Earth in terms of size in the known universe. Fressin led the team of researchers that found the planets.  

"The second one is 13 percent smaller than the Earth. With a diameter around 7,000 miles, which is also smaller than Venus, it is in fact the smallest planetary body ever discovered in orbit of another sun-like star. Most importantly, it is the first time we cross the Earth-size threshold. In other words, it is the first time that humanity has been able to detect a planet of Earth's size or smaller around another sun," Fressin said to the Guardian.  

Kepler-20e, the smaller of the two planets, orbits its sun every six days.  

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