Science article : Kepler -62f a Planet in The 'Habitable Zone'

Kepler -62f a Planet in The 'Habitable Zone'

            The discovery of a super-Earth-sized planet orbiting a sun-like star brings us closer than ever to finding a twin of our own watery world. A distant 'super-Earth' size planet known as Kepler-62f could be habitable, a team of astronomers reports. The planet, which is about 1,200 light-years from Earth in the direction of the constellation Lyra, is 40 percent larger than Earth. At that size, Kepler-62f is within the range of planets that are likely to be rocky and possibly could have oceans.

            On Earth, carbon dioxide makes up 0.04 percent of the atmosphere. Because Kepler-62f is much farther away from its star than Earth is from the sun, it would need to have dramatically more carbon dioxide to be warm enough to maintain liquid water on its surface, and to keep from freezing.

The team ran computer simulations based on Kepler-62f having:

• An atmosphere that ranges in thickness from the same as Earth's all the way up to 12 times thicker than our planet's.
• Various concentrations of carbon dioxide in its atmosphere, ranging from the same amount as is in Earth's atmosphere up to 2,500 times that level.
• Several different possible configurations for its orbital path.

They found many scenarios that allow it to be habitable, assuming different amounts of carbon dioxide in its atmosphere.

            The scientists made their calculations of the shape of the planet's possible orbital path using an existing computer model called HNBody, and they used existing global climate models (the Community Climate System Model and the Laboratoire de Me´te´orologie Dynamique Generic model) to simulate its climate. It was the first time astronomers have combined results from these two different types of models to study an exoplanet, the term for a planet outside our solar system.

            the same technique could be applied to understand whether exoplanets much closer to Earth could be habitable, so long as the planets are likely to be rocky. Scientists do not know whether life could exist on an exoplanet. More than 2,300 exoplanets have been confirmed, and a few thousand others are considered planet candidates, but only a couple dozen are known to be in the "habitable zone" -- meaning that they orbit their star at a distance that could enable them to be warm enough to have liquid water on their surfaces.