What do the first images from the James-Webb Space Telescope tell us?

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Six months after takeoff, now in orbit 1.5 million kilometers from Earth, the James-Webb telescope is working perfectly. The proof, he began to send us images of the cosmos with an unprecedented level of detail. Here are three of them told by three astrophysicists.

1galaxy cluster SMAC 0723

This is the very first image revealed by James-Webb. It was unveiled by US President Joe Biden on July 12, 2022, as in the heyday of the Apollo program in the 1960s. And it is already one of the most famous images in our universe.

This picture is “a deep field“, explains Nicole Nesvadba, astrophysicist and research director at the CNRS. “On points the telescope at a part of the sky where there are a priori no particularly bright objects to detect which ones are fainter in that part of the sky“. The result, then, is this photo on which appear thousands of galaxies, some of which are so distant that they appear to be a small red dot in the background.

It is these barely visible elements that are of particular interest to scientists. These are some of the oldest galaxies in the universe, formed more than 13.3 billion years ago. “In astronomy, the farther out into the universe you look, the farther back in time you look“, recalls Nicole Nesvadba. And James Webb, thanks to these faculties to see in the infrared, a light invisible to our eye, makes it possible to go back further than any other telescope before him.

2The Carina Nebula

The James-Webb Telescope is just a great time machine. It is also an instrument for analyzing the chemical composition of objects. In particular to understand the formation of stars like our sun.

Here we are in our galaxy, the Milky Way, about 7,500 light years away of the earth. And this is a nebula, also called a star nursery. “In the upper zone, with this blue background, we are in an area where the gas is very hot”explains Olivier Berné, astrophysicist at the Institute for Research in Astrophysics and Planetology in Toulouse and scientific program manager for the James-Webb space telescope. He pursues : “Towards the bottom, we see these orange nebulosities. These are called interstellar clouds. They are made up of gas and dust. Inside these clouds, where it is cold enough and the gravity is strong enough, clouds of gas and dust can collapse and form new stars. You can also see stars forming in some places.“.

Note that we can see a nebula with the naked eye in our sky. This is the Orion Nebula, located 1,500 light-years from Earth.

3Jupiter and its moon Europa

The James Webb’s infrared view is also beginning to scan objects in our solar system. A first photo of Jupiter was released on July 14.

“In this image we see Jupiter and one of its four moons called Europa“, describes Tristan Guillot, astrophysicist at the Observatory of the Côte d’Azur and specialist in the formation of gas giants. “Thanks to James Webb, we observe Jupiter with a high resolution in the infrared, so we observe the heat emitted by the planet, which will give us a lot of information on its composition. We will also be able to study this large red spot on the right. It’s an anticyclone that’s been there for 300 years that we don’t know much about,” rejoices Tristan Guillot.


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