we compared the images of the James Webb telescope with those of its predecessor Hubble

Have you ever seen stardust? The 32nd edition of “Starry Nights” will take place on August 5, 6 and 7. The possibility to observe the stars with the naked eye, with binoculars or even with the help of a telescope. But none will be as precise as the James Webb Space Telescope (JWST), the most powerful in the world, which makes it possible to observe space in a wealth of detail. One of its latest images, released Tuesday, Aug. 2, by NASA, shows dust and star-forming regions in the Cartwheel galaxy.

The James Webb telescope, the result of a collaboration between the American, European and Canadian space agencies, was supposed to make it possible to look further into space. And therefore to go further back in the past to hope to understand the formation of the universe. The comparison with its predecessor, the Hubble telescope, which had already taken similar images, allows us to appreciate this technological leap. Franceinfo asked astrophysicist Eric Lagadec, stardust specialist and president of the French Society for Astronomy and Astrophysics, to compare the James Webb and Hubble images.

Cartwheel Galaxy

The Cartwheel Galaxy is 500 million light years from Earth. The two space telescopes were able to capture it, but the shot taken by James Webb shows much more detail than Hubble.

In the image provided by Hubble in 2010, we guessed, without seeing them precisely, in the black areas inside the big blue circle, dust, the result of a collision between the Cartwheel galaxy and another galaxy. “Compression of dust and gas leads to the formation of new stars”explains Eric Lagadec.

Image of the Cartwheel Galaxy taken with the Hubble Space Telescope released in 2010. (ESA/HUBBLE AND NASA)

James Webb’s image shows these gas and dust dense regions much more explicitly. “With infrared we can now observe dust. Sometimes we can even see through it, but it depends on the conditions and properties of this dust”, analyzes Eric Lagadec. Finally, from the almost completely black background of the Hubble image, we move on to a background decorated with dozens of distant galaxies, made visible by James Webb.

Image of the Cartwheel Galaxy taken using the James Webb Space Telescope and released on August 2, 2022. (IMAGE: NASA, ESA, CSA, STScI, Webb ERO Production Team)

The Southern Ring Nebula

Its scientific name is “NGC 3132”, but it is rather called the “Austral Ring Nebula” or the “Eight Shards Nebula”. This expanding cloud of gas is located at a distance of about 2,000 light years. It is therefore one of the closest known planetary nebulae to Earth, according to NASA.

The central star visible in the center of the Hubble image released in 1998 is dying. “As a result, it contracts and heats up. This will excite the gas around it and give different colors picked up by Hubble,” describes Eric Lagadec.

Image of the Southern Ring Planetary Nebula (NGC 3132) taken by the Hubble Telescope and published in 1998. (HUBBLE HERITAGE TEAM (STSCL / AURA / NASA))

In James Webb’s image, the red and more distant parts are actually colder gas because it has already been ejected by the star and dust. It is invisible with Hubble, but JWST’s infrared technology makes it possible to represent this gas.

Image of the Southern Ring Planetary Nebula (NGC 3132) taken by the new James Webb Telescope and released on July 12, 2022. (NASA, ESA, CSA, STScI)

The Carina Nebula

It looks like steep mountains in these pictures. It is actually one end of the Carina Nebula. Called “cosmic rocks,” these enchanting shapes are located on the edge of a giant gaseous cavity in NGC 3324, located about 7,600 light-years away, we learn on the James Webb website.

The shades of yellow and red in the two images again represent areas of dust and gas where new stars form, explains Eric Lagadec.

Image of one end of the Carina Nebula taken by the Hubble Telescope released in 2008. (NASA / ESA / HUBBLE TEAM HERITAGE)

James Webb’s image is so precise that it allows you to observe many details. Places with more or less dust stand out in the image, like the layers of a mountain. “This picture is beautiful!” rejoices Eric Lagadec, who admits to having made it his mobile phone wallpaper.

Image of one end of the Carina Nebula taken by the new James Webb Telescope and released on July 12, 2022. (NASA, ESA, CSA, STScI)

Stephan’s Quintet

Stephan’s Quintet is a group of five galaxies located in the constellation Pegasus. The interaction between these galaxies creates star formation zones, suggests Eric Lagadec. “With Hubble we see more stars and hot gas, with Webb more dust and cold gas”, describes the astrophysicist.

Image of Stephan's Quintet taken by the Hubble telescope and released in 2009. (ESA / HUBBLE)

The image below is the largest to date by James Webb and covers about a fifth of the Moon’s diameter. It contains more than 150 million pixels and is built from nearly 1,000 separate image files, according to the telescope’s website.

Image of Stephan's Quintet taken by the new James Webb Telescope and released July 12, 2022. (NASA, ESA, CSA, STScI)

What impresses above all is the amount of galaxies visible in the distance. Amounts of celestial bodies yet to be discovered.

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