On December 25, 2021, an Ariane 5 rocket left the Kourou launch pad in French Guiana. Under the cover of the device, one of NASA’s treasures. The James Webb Space Telescope, named in honor of the administrator of the space agency during the 60s and 70s, had the mission of revolutionizing our knowledge.
A year after its launch, the telescope has delivered on its promises. He even did better than expected. Positioned for months on the Lagrange L2 point, a place in the sky where the gravitational forces of the Earth and the Sun cancel each other out, James Webb has turned his mirror towards the deep Universe.
James Webb: a telescope like no other
During the presentation of the first images of the telescope, the emotion was immense. In order to compare NASA’s technological advances and the power of the device, the teams in charge of the configuration targeted an area of the sky already studied by Hubble, another space telescope well known to the general public.
The difference between the two photos is striking. Below you can admire on the left the image taken by James Webb in 2022 and on the right, that of Hubble, made 30 years before. The gap between the two devices is abysmal. Scientists expected to be surprised, but not so much.
On the left the Hubble photo and on the right the same image taken by the James Webb Space Telescope © NASA
Since then, the James Webb Space Telescope (JWST) has multiplied the shots. In particular, he photographed the Carina Nebula, a region of the sky known to be a “star nursery”. In this dense fraction of our sky, pockets of gas gather under the effect of gravity. Matter condenses to the point of creating nuclear fusions, giving birth to stars.
Olivier Berné, a researcher in Toulouse, was the first Frenchman to be able to use James Webb to point out these nurseries. For Presse-Citron, we discussed this observation, which is obviously not like the others.
The Carina Nebula, a stellar nursery, seen by James Webb © NASA
But the James Webb Space Telescope has also allowed scientists around the world to discover better-known areas of our sky. Closer to us, the mirror of the large telescope recently observed Mars or the Dimorphos meteorite at the heart of the DART mission.
© On the left the impact of the DART mission seen by Hubble, on the right the same impact seen by James Webb
The device is now used for several crucial missions. The first of these is the search for and observation of exoplanets. These objects revolve around a star, sometimes millions of light years from Earth. Thanks to the precision of its mirrors, the James Webb Space Telescope is able to describe (thanks to spectroscopy) the composition of the atmospheres of these distant worlds.
James Webb: the perfect tool to understand the Universe
The researchers hope to find through their experiments planets likely to harbor life. They would be the irrefutable proof that we are not alone in the Universe. Such a discovery could answer one of the oldest questions in the history of the human species.
One of the first images taken by James Webb © NASA
But with his hexagonal mirror, James Webb also wants to unravel the mysteries of the Universe as a whole. By observing very distant stars, the telescope is able to go back in time. The speed of light being finite (300,000 km/s), objects located billions of billions of kilometers from the Earth appear to us as they were when the light left their surface.
By fixing them, it is thus possible to go back to the first moment of the Universe. 13 billion years ago. It is then possible to understand what were the living conditions in this primitive world. Such knowledge makes it possible to unwind the thread of the world until our arrival on Earth.
