On the program: two nebulae illustrating the life cycle of stars, an exoplanet, and a compact group of galaxies.

The event is to be broadcast live from the Goddard Space Center in Maryland, near Washington in the United States, at 10:30 a.m. local time (2:30 p.m. GMT).

On Monday, a first image taken by the telescope, illustrating the distant times of the cosmos, was unveiled, in the presence of US President Joe Biden, who hailed a "historic" moment.

The shot, which is teeming with detail, shows galaxies formed shortly after the Big Bang, more than 13 billion years ago.

One of James Webb's primary missions -- a $10 billion engineering gem and the most powerful space telescope ever designed -- is indeed the exploration of the very young Universe.

This first demonstration was intended to give an overview of its capabilities in this area.

But it was only one of five targets announced by NASA for this surprise bag, which officially marks the beginning of scientific observations of the telescope, and whose contents had so far been carefully kept secret in order to raise suspense.

The images of two nebulae -- very photogenic and gigantic clouds of gas and dust -- will be unveiled on Tuesday, and promise to be spectacular.

The Carina Nebula, located about 7,600 light-years away, should illustrate star formation.

It is home to many massive ones, several times the size of our Sun.

The Southern Ring Nebula is a so-called planetary nebula (although it has nothing to do with planets): it is an immense cloud of gas surrounding a dying star.

An image showing in particular US President Joe Biden and Vice-President Kamala Harris during the publication of the first image from the James Webb Space Telescope, July 11, 2022 at the White House - NASA TV / AFP

Another target: Stephan's Quintet, a group of interacting galaxies.

Scientific Adventure

The last cosmic object whose observation will be revealed on Tuesday is an exoplanet, that is to say a planet in orbit around a star other than our Sun – one of the main lines of research of James Webb.

It was not actually photographed, but analyzed by spectroscopy, a technique used to determine the chemical composition of a distant object.

In this case, WASP-96 b, a giant planet composed mainly of gas.

By combining the data obtained previously thanks to other telescopes and those by James Webb, "we will probably be able to detect water vapor" in its atmosphere, estimated with AFP José A. Caballero, astronomer at the Centro de Astrobiologia in Spain and specialist in exoplanets.

The James Webb Telescope Jonathan WALTER AFP

These data "will be interesting for me to see the capabilities of the telescope and the instruments", he added, even if he considers this first exoplanet a bit "boring", and looks forward to smaller and less hot ones. are observed.

James Webb had been launched into space about six months ago, on Christmas Day, from French Guiana by an Ariane 5 rocket. The result of a huge international collaboration, and in the works since the 1990s, he is posted 1.5 million kilometers from Earth.

The publication of these first images marks the beginning of an immense scientific adventure, which must extend over many years and transform our understanding of the Universe.

Researchers around the world have reserved observation time with James Webb, whose program for its first year of operation has already been carefully determined by a committee of specialists, and made public.

© 2022 AFP