Young French astronomer is first author of the paper on the discovery of a "new Earth"

François Fressin, a French astronomer expatriated at the Harvard-Smithsonian Center for Astrophysics in Cambridge (Massachusetts), is the first author of a study published in Nature on Tuesday, December 20th, announcing the discovery of two extrasolar planets of a comparable size to the Earth.

Those two objects belong to a five-planet system orbiting around Kepler-20, a star located at a distance slightly less than 1,000 light-years and very similar to our Sun, though a little bit less heavy, hot and luminous. Among those five objects, three are mini Neptunes and two are cousins of the Earth. Named Kepler-20e and Kepler-20f, they are very similar in size to our blue planet with respective radii of 87% and 103% of the Earth’s.

“For the first time in the history of humanity , we can stand: “that is, we are able to detect an Earth-like planet around another star. It is even the first time that we pass the barrier of smaller than the Earth” summarizes François Fressin.

This 33-year-old Frenchman specializes in the research of small planets using the data that NASA’s Kepler space observatory has sent back to Earth since 2009. This observatory orbiting around the Sun is constantly observing a catalog of stars located within and around the Cygnus constellation. Kepler’s instrument is a photometer, which measures minor variations of light emission. Its main objective is to detect the very low drop of the luminosity due to the passage – the transit, as astronomers say – of a planet in front of its star. To give an order of magnitude, Kepler-20e and f cause a diminution of this luminosity of one millionth. That is small, but sufficient for specialists to be sure that something is going on, and even more when these “hollows” in the luminous flux happen at regularly spaced intervals.

Kepler Satellite