More than 5000 exoplanets discovered and inevitably a form of life somewhere
The 5000th extrasolar planet has just been added to Nasa's official catalog. The discoveries have been made at a steady pace, since 1000 new specimens have been confirmed in only two and a half years. For the astronomer Alexander Wolszczan, who identified the very first exoplanet in 1992 around a pulsar, it is inevitable that one day life will be found there.
Nasa announced on March 21, 2022, that the symbolic bar of 5000 exoplanets formally identified had just been crossed following the addition of 65 new specimens to the catalog (Nasa Exoplanet Archive) of the U.S. Space Agency. They form a bestiary of great diversity. Among these objects: small telluric planets similar to Earth, miniature versions of Neptune, "hot Jupiters" very close to their star, gas giants even more imposing than the Jovian star or "super-Earths" much more massive than our planet but which nevertheless have a rocky surface ... Not to mention the objects orbiting a pair of stars or subsisting in the vicinity of collapsed stellar bodies. "Each one is a world unto itself, a whole new planet," enthused Jessie Christiansen, the astrophysicist who is leading the catalog, in a statement. And I'm excited about all these planets because we don't know anything about them yet."Giant planets without equivalent in the Solar System
Giant planets without equivalent in the Solar System
The first detections of exoplanets were confirmed in 1992, just thirty years ago. They were orbiting around a certain type of neutron star, called a pulsar, rotating very rapidly around itself and emitting intense radiations with a frequency of the order of a millisecond. Three years later, in 1995, Swiss astronomers Michel Mayor and Didier Queloz discovered the first exoplanet around a star similar to the Sun. They based their discovery on the slight recoil caused by the rotation of the planet around the star. The planet in question was a "hot Jupiter": a giant planet without equivalent in the Solar System, very close to its star and making a complete revolution in only four days (against 12 years for our Jupiter).
An extremely successful method
From 2009, another method of detection - called "transits" - will prove extremely fruitful. It consists in recording tiny decreases in luminosity (of the order of 1%) when a planet passes in front of its star, a bit like an eclipse. Operated by NASA between 2009 and 2018, the Kepler space telescope has been able to locate more than 2700 exoplanets, the majority of the 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 of the European Southern Observatory, the American space telescope TESS (Transiting Exoplanet Survey Satellite) or, since 2019, the European CHEOPS (CHaracterising ExOPlanets Satellite). With great success. Because if 4,000 exoplanets were identified in the summer of 2019, it will take less than three years to add 1,000 more.
The discovery of extraterrestrial life is only a matter of time
owever, the quest has only just begun. Of the 5,005 objects counted to date, 98% are located in our "close vicinity", only a few thousand light-years from our star. Myriads of others remain to be discovered among the hundreds of billions of exoplanets that would populate our galaxy. Faced with such possibilities, such dizzying numbers, "it is inevitable that we find a form of life somewhere," says astronomer Alexander Wolszczan, who with his team had discovered the first exoplanet in 1992. "The close connection between the chemistry of life on Earth and that at work in the Universe, as well as the widespread presence of organic molecules, suggest that the detection of life itself is only a matter of time."
The atmosphere of exoplanets under the JWST microscope
Expected for the end of the decade, the next generation of terrestrial and space telescopes like the American Nancy Grace Roman Space Telescope or the European ARIEL (Atmospheric Remote Sensing Infrared Exoplanet Large-survey) will perhaps allow these decisive discoveries. But in the meantime, all eyes are on the JWST (James Webb Space Telescope). Built by the American, European and Canadian space agencies, it is currently undergoing calibration at 1.5 million kilometers from Earth. With a main mirror of 6.5 meters in diameter, it is the largest and most powerful observatory ever sent into space. And from this summer, it will be able to scrutinize the atmosphere of exoplanets - especially gas giants - with an unequalled precision, by looking for possible bio-signatures such as ozone molecules for example.
source : ( https://www.sciencesetavenir.fr/espace/vie-extraterrestre/plus-de-5000-exoplanetes-decouvertes-et-forcement-quelque-part-une-forme-de-vie_162352 )