5,000 exoplanets are now known: an important milestone for planetary science

5,000 exoplanets are now known: an important milestone for planetary science

NASA's Jet Propulsion Laboratory announced on Monday that there are now 5,000 exoplanets in our space notebook, and this is just the beginning, and the new telescopes under construction promise to significantly expand this sample over the next decade.

Not so long ago, only a small number of planets orbiting our sun were known, and everything changed in 1992 with the first confirmed discovery of the extra-terrestrial planet. In the journal Nature astronomers Alex Volshon and Dale Freil reported that they were able to detect two worlds orbiting the pulsar. Three years later, the team announced the discovery of the first planet around a star similar to the sun.

All these exoplanets were detected using a radial velocity method that measures the small fluctuations of stars caused by the presence of their planets. Large worlds were easier to detect because they caused large fluctuations. In order to find smaller, Earth-like worlds, astronomers developed another method: the "transit" method, which is designed to measure the tiny variation of light at the intersection of their star's face.

Astronomer William Boruki was one of the first to develop this method during the work on the Kepler Space Telescope, launched in 2009 and out of service in 2018, the observatory is now responsible for the discovery of more than 2,700 exoplanets. Not all the data collected during its operation have been analysed, so that several other worlds may be hidden in this archive.

Since the launch of Kepler, many other instruments have joined the hunt for planets, including the HARPS spectrograph installed at La Sylla and TESS, launched into space in 2018.

In recent years, discoveries have accumulated. NASA's exoplanet archive is located at the California Institute of Technology. To be added to the catalogue, these planets must be independently confirmed by at least two different methods, and the work must be published in a peer-reviewed journal.

On Monday, March 21, the catalogue recorded a new batch of 65 exoplanets, bringing the number of officially known worlds to 5,000, including small rocky planets such as the Earth, gas giants a few times larger than Jupiter and hot Jupiters, which are very close to their stars.

Based on this sample, astronomers suggest that there may be between 100 billion and 200 billion planets in our galaxy, so the search continues. Other instruments of the new generation will soon join the current telescopes.

The Roman Nancy Grace Space Telescope, which is scheduled to be launched in 2027, will make new discoveries using a variety of techniques. The ESA ARIEL mission, launched in 2029, will focus on studying the atmosphere of the exoplanet, as will the James Webb telescope, which is expected to begin its first observations this summer.