Welcoming super-Earths , Exciting details , So nice

There are undoubtedly countless extrasolar planets. But what do they look like? Models suggest that many of them would be similar to the Earth, and could harbor life

You are contemplating the night sky. You look in the direction of a star around which revolves, have you read a particular planet status. Even if you can not see - you see only the star itself - you know it is several times larger than Earth and essentially consists of rocks. Sometimes earthquakes shake the surface, which is largely covered with oceans. Its atmosphere is not so different from what we breathe, and its sky is swept from frequent storms and often obscured by volcanic ash. Home she lives? According to scientists, it is not impossible ...

This astronomical dream could soon become reality. Although most of the 500 extrasolar planets discovered to date are gas giants like Jupiter instead, astronomers began to discover some - notably through the European space telescope CoRoT - which might not be very different from Earth. And the American Kepler Space Observatory, launched last year, probably discover more.

Of course, these exoplanets are in light years, so that even our most sophisticated telescopes are not able to discern the details of their surface (mountains, clouds, seas, etc.). Maybe they can do forever. In general, we can only highlight indirectly the presence of a planet, and estimate its mass and size of its orbit. In some cases, the instruments were able to obtain information on the diameter of the planet and some other details. Thus crudely known atmospheric composition and dynamics of the winds of some gas giant exoplanets.

We are far from precise measuring data on the geology, chemistry or other characteristics of exoplanets. Yet from some things, researchers are able to draw complex portraits of these distant planets, using theoretical models, numerical simulations and even laboratory experiments, combined with established knowledge for the Earth and the other planets of the solar system.

In our research, for example, we modeled the composition of planets similar to Earth. We found that such planets even when they are much more massive than our own, seem geologically active and have an atmosphere and a climate that could be favorable to life. In fact, the Earth may be located at the lower limit of the possible mass range for a planet to be habitable. In other words, if the Earth were a little smaller, it would have become as barren as Mars or Venus.

The first super-Earths

The first extrasolar planet was discovered in the mid 1990s by the "radial velocity" method, which is to detect the presence of a planet by its gravitational effects on its star. The gravity of the planet prints a slight rocking motion to the star; movement that is detected as a shift of the spectrum of the sun.

In the early days, some researchers wondered if these were the result of physical oscillations of the star or the presence of orbiting planets. There are about ten years, one of us, D. Sasselov, while specialist variable stars, helped to show that the oscillations were well caused by planets, thus validating the radial velocity method.

D. Sasselov then joined the project of the Kepler Space Observatory, designed to search for exoplanets. Kepler was finally put into orbit in 2009. As CoRoT, it is designed to detect planets by the transit method, that is to say by observing the brightness of small periodic cuts of a star when a planet in orbit passes in front of her. The Kepler telescope is pointing to a small region of the sky near the constellation Cygnus. Its wide-angle camera will follow approximately 150,000 stars continuously for three years. Kepler is expected to find hundreds of new planets, some as small as Earth.

From the earliest stages of mission planning, D. Sasselov realized that scientists would not know necessarily exploit the mass of data produced by Kepler. For example, nobody had then modeled the process ...

Source : For the science