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Webb can also see much redder infrared wavelengths, opening up a new view of the universe. This is especially important to study the early universe because of “cosmological redshift”, a process that refers to the stretching of light (with the expansion of the universe) as it travels through outer space.

It’s also useful for studying fascinating resources such as planets orbiting nearby stars and the regions where stars are formed.

We’ve previously written about the enormous engineering challenges associated with Webb’s construction and his journey to orbit. Now, with the highly anticipated first images in our hands, let’s take a look at what they show.

Intense brightness

In a sneak peak, US President Joe Biden presented the first-ever image of Webb’s ‘deep field’. This is the massive galaxy cluster SMACS-0723 that contains thousands of galaxies clustered around a central super-bright galaxy crouching in the center.

The giant southern cluster SMACS 0723 was captured by Webb.


You will immediately notice the many elongated arcs, which represent background galaxies that have been “gravity lensed” due to the mass of the cluster. In other words, the massive gravitational pull at play has caused the light from the galaxies to be distorted (stretched) and amplified, creating a vastly enhanced picture of the distant universe.

The clarity is amazing, especially in terms of the structure of the lenses. Here’s a zoomed-in look at a small area, compared to a similar exposure image from Hubble:

A comparison of Webb (left) and Hubble (right) in their view of the same region. This is a zoomed in area of ​​the deep Webb field.

Adapted from images from NASA, ESA, CSA and STScI

The magnified images above show a deep-field region containing a spiral galaxy that astronomers have affectionately called “The Slug.” It is several times further than the SMACS-0723 cluster.

But our eyes were drawn more to the very thin arch just above it (marked with arrows). This little piece demonstrates Webb’s power. This arc was barely detected by Hubble, but Webb sees the “beads on a string” clearly. They are likely individual star clusters in the extremely distant, small galaxy.

We can see similar amazing details everywhere in the deep field. For point-like objects, Webb is expected to be more than 100 times more sensitive than Hubble, and this certainly shows it.

The field is also dotted with some faint red objects, which are already attracting the attention of experts. Some of these could potentially be the most distant galaxies, where light has taken the longest to reach us.

Reveal Hidden Elements

Webb is also capable of extremely sensitive infrared spectroscopy, which splits light into wavelengths to reveal an object’s composition.

While Hubble is very bad at this, Webb manages to do it beautifully – shown below through the spectrum of the massive planet WASP 96b. About 1,120 light-years away, this planet weighs about half the mass of Jupiter.

Webb captured the spectrum of exoplanet WASP-96b, a hot gas giant.


The dips in the spectrum reveal the presence of water vapor in the planet’s atmosphere. Now WASP 69b is unlikely to harbor life due to its proximity to its parent star. Still, this demonstration is very exciting because the same method can be applied to the approximately 5,000 other known exoplanets.

Spectroscopy will eventually allow us to detect potential features of life, such as ozone and methane.

Seeing dust and gas

The third image is of the Southern Ring Nebula, about 2,000 light-years away in the Milky Way. This image shows Webb’s mid-infrared capability (which is again far beyond Hubble’s reach).

The planetary nebula in the Southern Ring, with a near infrared image on the left and a mid infrared image on the right.


It’s a classic example of a “planetary nebula” (a misnomer because it doesn’t involve a planet) in which the central star has been transformed into a small white dwarf by blowing off its outermost layer. This happens at a speed of about 15 kilometers per second, emitting rings of gas and dust.

The brightest star at the center is actually a companion star, and the white dwarf is the fainter partner, visible only in the mid-infrared because it is obscured by dust. The mid-infrared also highlights the dust formed in the expanding gas.

The fourth image below shows Webb’s view of nearby galaxies. Here we see a famous galaxy group called Stefan’s Quintet, about 290 million light-years away. The five galaxies are close to each other. Four interact and cause abundant star formation.

Stephan’s Quintet is a compact group of interacting galaxies.


The red streaks and clumps show the location of new star formation through the associated dust. The detail of the dust distribution and the tug-of-war between the galaxies jumps out of the picture. And the mid-infrared reveals light from a supermassive black hole at the center of the upper galaxy.

Also striking is the vast sea of ​​distant galaxies in the background. We expect to see this in every Webb image, even when Webb points to sources within the Milky Way. This is because infrared light passes through dust. Webb’s infrared detection capabilities are so sensitive that they can see right through objects in our galaxy.

This means distant background galaxies will bombard every Webb image. See if you can spot them in the images of the Southern Ring and Carina.

And finally we have Webb’s tribute to Hubble’s famous Pillars of Creation image.

The Carina Nebula, a cosmic nursery surrounded by gas and dust.


This infrared image shows the Carina Nebula, a stellar nursery of gas and dust 7,600 light-years away, where new stars are forming and destroying their birth clouds.

The image is extraordinarily complex and the intricate swirls of dust, gas and young stars are breathtaking. It will probably take astronomers many years of hard work to figure out exactly what’s going on here.

These handful of sample images alone, a few days of work for Webb, have provided astronomers with vast amounts of new data that will fuel years of research. And that’s just the beginning.The conversation

Karl GlazebrookARC Laureate Fellow & Distinguished Professor, Center for Astrophysics & Supercomputing, Swinburne University of Technology and Simon Driverprofessor of astrophysics, The University of Western Australia

This article was republished from The conversation under a Creative Commons license. Read the original article.

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