The search for other "Earths" in space continues 30 years later.

In 1995, Swiss scientists Michel Mayor and Didier Queloz confirmed for the first time the presence of a planet in a system other than our own. This discovery, commemorated last Friday by the University of Geneva, where they both worked, opened up the field of astronomy to the search for exoplanets capable of supporting life, like Earth.

The prestigious research center, whose Astronomy Department the two experts were part of in 1995, has opened an exhibition in downtown Geneva, on the shores of Lake Geneva, to commemorate the anniversary, and will organize several conferences to this end, one of them featuring the now-retired Mayor.

On October 6, 1995, both scientists announced the detection of a planet they named 51 Pegasi b, later also known as Dimidium , an achievement that Thus, a quarter of a century later, in 2019, both would be awarded the Nobel Prize in Physics.

The discovery of the star, almost 51 light-years away—similar in size to Jupiter, although much closer to its star than Jupiter is to the Sun—was achieved using the radial velocity system, which measures the slight oscillations of a star caused by the proximity of a planet.

Queloz and Mayor used data obtained by the ELODIE spectrograph at the Haute-Provence Observatory in southeastern France, where they had already begun to suspect in 1994 that an object was orbiting the star 51 Pegasi every 4.2 days, although it took them a year to be certain it was a planet.

Read: What happens if I eat bolillo every day? Exoplanets are getting smaller and "colder"

That discovery opened the door to a new branch of astronomy, exoplanetology, in which more than 5,000 planets have already been discovered— surely a tiny fraction of the total, considering that our galaxy, the Milky Way, alone has hundreds of billions of stars.

At first, only the largest exoplanets closest to their stars could be observed, but especially In the last 10 years, the search has been further refined to bodies whose smaller size or greater distance from their "suns" may more likely allow life, with rocky planets instead of gaseous ones, more stable atmospheres, and suitable temperatures.

Scientists are already managing to analyze the atmospheres of some of these exoplanets, something key to searching for possible signs of life on Neptune-sized stars, Queloz explained in a recent interview with Swiss national television station RTS .

The CHEOPS satellite, or the ESPRESSO spectrograph— designed in Geneva and installed by the European Southern Observatory (ESO) at the Chilean Atacama Desert Telescope System—is leading the current search, using new systems such as the so-called transit method, which detects small, periodic dips in a star's light when a planet passes in front of it.

Finally another planet with life?

News of new exoplanet candidates to be "Earth B" are happening with increasing frequency, and finally Last April, the James Webb Telescope announced the discovery of "signs of biological activity" on one of these planets, located 124 light-years from ours.

Researchers working with data from the James Webb Space Telescope have identified molecules such as dimethyl sulfide on the exoplanet, which on Earth are associated with biological processes, although this detection has not reached the statistical threshold necessary to confirm the presence of life.

The discovery of the exoplanet, called K2-18b , with a mass eight times greater than that of Earth and which, according to its researchers, could be covered in water, has been recognized as a breakthrough, although astronomers such as Queloz himself warned of the need to take it with caution.

"Detecting life through a planet's atmosphere is extremely complicated. First, you have to understand how the planet works, then its atmosphere, and finally, how life emerges," Queloz explained.

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AO