NASA announced on March 21, 2022 that the symbolic bar of 5,000 formally identified exoplanets has just been crossed after 65 new samples were added to the US space agency’s catalog (NASA Exoplanet Archive). They make a bestiary of great variety. Among these objects: small telluric planets similar to Earth, miniature versions of Neptune, “hot Jupiters” much closer to their star, grander than the gas giant Jovian star, or even “super-Earths” from our planet are more massive, but which will nevertheless have a rocky surface … not to mention objects orbiting around some stars or remaining near stellar corpses that have fallen. ,Each of them is a world in itself, a whole new planetIn a press release, excites Jesse Christiansen, the astrophysicist who directed this catalogue. And I’m excited about all these planets because we don’t know anything about them yet,

giant planets without counterparts in the solar system

The first detection of exoplanets was confirmed in 1992, so only thirty years earlier. They orbited a certain type of neutron star, called a pulsar, which spins very rapidly around itself and emits intense radiation with a frequency of the order of milliseconds. Three years later, in 1995, Swiss astronomers Michel Mayer and Didier Queloz discovered the first exoplanet around a Sun-like star. For this they relied on light-speed motions caused by the planet’s rotation around the star. The planet in question was a “hot Jupiter”: a giant planet that has no counterpart in the Solar System, being very close to its star and making a complete revolution in just four days (compared to 12 years for our Jupiter). .

a very successful way

From 2009, another method of detection – called “transit” – would prove extremely useful. When a planet passes in front of its star, tiny droplets of light (about 1%) are recorded in it, much like an eclipse. Operated by NASA between 2009 and 2018, the Kepler space telescope was able to identify more than 2,700 exoplanets, the most objects listed to date. Other instruments have come to reinforce this tracking, such as the Hubble Space Telescope, the HARPS (High Accuracy Radial Velocity Planet Searcher) spectrograph from the European Southern Observatory, the American Space Telescope TESS (Transiting Exoplanet Survey Satellite) or, since 2019, the European Satellite CHEOPS (Featuring Exoplanet Satellite). with great success. Because if 4,000 exoplanets were identified in the summer of 2019, it would take less than three years to add 1,000 more.

The search for extraterrestrial life will only be a matter of time

However, the search has just begun. Of the 5,005 objects counted to date, 98% are located in our “near environment,” a few thousand light-years away from our star. Thus out of the hundreds of billions of exoplanets, many more remain to be discovered that will populate our galaxy. Facing such possibilities, such startling numbers,”It is inevitable that we will find a form of life somewhere“Astronomer Alexander Volszczn, who first discovered the exoplanet with his team in 1992, estimated.”The close relationship between the chemistry of life on Earth and work in the universe, along with the widespread presence of organic molecules, suggests that it is only a matter of time to detect life.,

The atmosphere of the exoplanet under investigation by JWST

Expected for the end of the decade, the next generation of terrestrial and space telescopes such as the American Nancy Grace Roman Space Telescope or the European ARIEL (Atmospheric Remote Sensing Infrared Exoplanet Large-Survey) could allow these decisive discoveries. But in the meantime all eyes are on JWST (James Webb Space Telescope). Built by the American, European and Canadian space agencies, it is currently in the calibration stage at a distance of 1.5 million kilometers from Earth. Equipped with a main mirror of 6.5 meters in diameter, it is the largest and most powerful observation instrument ever sent into space. And from this summer, it will be able to scan the atmosphere of exoplanets – especially the gas giants – with unmatched accuracy, especially looking for any biosignatures such as ozone molecules, for example.