Planets outnumber stars in the Milky Way, according to an astronomical study published today in the journalNature. After six years of searches, in which millions of stars were mapped, the team led by Arnaud Cassan, from the Institute of Astrophysics in Paris (France), has concluded that the existence of planets around stars is the norm, more than the exception. The finding by Cassan and his colleagues relies on the use of the gravitational microlensing technique, the same one used for the discovery of a dozen extrasolar planets. Specifically, the astronomers used observations provided by the PLANET and OGLE programs, in which exoplanets are detected by the way in which the gravitational field of their host star, combined with that of possible planets, acts like a lens, magnifying the light from the background star.
After six years of searching, researchers have calculated that there are around 100,000 million planets in our galaxy . On average there are 1.6 planets per star . And they are more numerous the smaller their size. Specifically, astronomers have concluded that one in six stars studied hosts a planet similar in mass to Jupiter , half have planets similar in mass to Neptune, and two-thirds have super-Earths . The mapping was sensitive to the detection of planets that were at a distance from their star between 75 million kilometers and 1,500 million kilometers (in the Solar System this range includes all planets from Venus to Saturn) and with mass ranges that They range from five times the mass of Earth to ten times that of Jupiter.
? Before we believed that the Earth could be unique in our galaxy. But now it seems that there are literally billions of planets with masses similar to Earth orbiting stars in the Milky Way? concludes Daniel Kubas, co-author of this article.
