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Earth finally discovered his first big sister

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- By Marielle Court
- Published on 23/07/2015 at 19:18

Artist's impression of Kepler- 452b and his "Sun".

NASA presented this Thursday a planet and a half times larger than ours. It is located in the "habitable zone" of a Sun-like star, 1,400 light-years.

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The family continues to grow: after the false binoculars and cousins , Earth now has a big brother: Kepler-452b.Located 1400 light years from the Solar System, it is one and half times larger than our planet orbit but on the other hand around a star similar to our Sun and a similar distance. It thus puts 385 days to go around, or more or less an Earth year, and is thus in the habitable zone of its star, namely on a fully compatible orbit with the existence of liquid water on its surface. This does not mean that we will necessarily find oceans or waterfalls, much less that it is home life, but simply that it is neither too close nor too far from its parent star so that it is absurd to ask. Although it is a little overweight (she probably made five times the mass of Earth), this is the first rocky planet a priori located in the "habitable zone" of a star similar to our sun .

Scientists from NASA have therefore announced this discovery in style Thursday night at a press conference on the latest analysis of data from the satellite tracker exoplanet Kepler, whose discovery of this kind of world was the main goal. For this, it detects small brightness drops caused by the passage in front of their star. He amassed a very large amount of observations between 2009 and 2013 before breaking down.

We need more of these small eclipses to validate the detection of an exoplanet. At least three.Ideally five to ten. In the case of Kepler-452b, there is no more than four, occurred between 2010 and 2013. He could not be any more since the planet takes a year to circle its star ...

The number of exoplanets exploded

This first big sister is not quite a surprise. Since the discovery of the first planet outside the solar system in 1995, the number of these exoplanets has exploded. We count about 2000 (the exact figures vary catalogs). If the gas giants close to their star are overrepresented because easier to detect, instrumental advances have gradually uncover rocky worlds around stars more brilliant. The discovery of this sister is another step in that direction. Even though it is a little larger than our planet, it is the first to be around a star like our sun.

The Earth already had a dozen cousins, one or two fraternal twins, ie rocky planets located in the habitable zone of their star, but very different stars from the Sun as much lower. As Kepler-452b, it is however still not know the exact mass of these planets: the forces of gravity they exert on their parent stars are still too low to be detected. Similarly, it is still impossible to study the atmospheres of such worlds watching how the light passing through them changes.

To make a step forward, it will probably be in the next decade the new space missions to hunt: the American and the European Tess Plato. Kepler, it is not yet retired but, since its failure in May 2013, no longer works as a degraded mode called K2. The data accumulated during its heyday, however, not yet revealed all their secrets. The proof is provided today by this discovery. Even more advanced statistical analyzes could perhaps afford to still draw some interesting planets in the coming years.One or two dozen candidates include cousins-in boxes.