NASA finds Earth`s twin 1,400 light years away

U.S. space agency NASA confirmed on Thursday (local time) that scientists have found Kepler 452b, a body 1,400 light-years away, that is the most Earth-like exoplanet ever found yet. Before the discovery of Kepler-452b, Kepler-438b found in January this year was considered "the closest twin to Earth, or the Earth 2.0" as it is 12 percent bigger than Earth and has rocks.

"We can think of Kepler-452b as an older, bigger cousin to Earth," said Jon Jenkins, Kepler data analyst at NASA`s Ames Research Center. Kepler-452b`s host star is 6 billion years old, 1.5 billion years older than the Sun. The exoplanet is 1.6 times bigger than Earth in diameter.

Kepler-452b was discovered by NASA`s Kepler Space Telescope, which was sent to space in 2009 to seek out Earth-sized planets that can support life outside of the solar system. The telescope has so far discovered 1,030 candidate planets, including Kepler-452b. The scope has found 12 planets that reside in the habitable zone, known as the "Goldilocks Zone," a sweet spot in a solar system where a planet’s surface temperature is neither too hot nor too cold.

Among the 12, scientists are paying attention to Kepler-452b, as its system is the most similar to our solar system. Just as Earth orbits the Sun, Kepler-452b circles around its sun, Kepler-452. Kepler-452b orbits its star in a 385-day cycle, similar to Earth`s 365 days. In addition, Kepler-452`s surface temperature is similar to that of the Sun, belonging to the same G2 group.

"Kepler-452b is the first exoplanet ever found to be orbiting around a G2 star, whose temperature is similar to our sun," said Kim Seung-ri, head of the variable objects group at the Korea Astronomy and Space Science Institute.

Keplar-452b is believed to be made of rock. NASA said that the exoplanet will provide an opportunity to understand the environment of Earth`s evolution.

yskwon@donga.com