Analyzing an Invisible Universe Captured by NASA’s James Webb Space Telescope


It is a rare delight for a sequel to be as good as the original, but the second image release from the James Webb Space Telescope certainly lived up to expectations set by Monday evening’s thrilling deep field reveal. As a matter of fact, it surpassed it by leaps and bounds.

The unveiling of that first image by President Joe Biden wasn’t exactly impressive, but the image itself? Magnificent. Known as “Webb’s First Deep Field,” it gives astronomers a look at galaxy cluster SMACS 0723. 

A view of hundreds (perhaps thousands) of galaxies in deep space

JWST’s First Deep Field was revealed on July 11.

NASA, ESA, CSA, and STScI

What you’re looking at is a minuscule patch of the Southern Hemisphere sky — equivalent to a grain of sand held up to the heavens — yet replete with thousands of galaxies, from spirals and ellipticals to simple pinpricks of light only a few pixels wide. And thanks to a phenomenon known as gravitational lensing, it provides us with the deepest, and oldest, view of the cosmos yet — as well as concrete proof of Albert Einstein’s general relativity. That’s a lot to live up to, right? 

Well, even though the images released Tuesday don’t reach quite so far back in space and time, they are undoubtedly profound, equal to the First Deep Field in beauty and delicately woven with exquisite cosmic detail. 

Three major images make up the JWST’s first full-color set. 

Two focus on nebulas, huge clouds of dust and gas within which stars are sometimes born, and the other analyzes a region known as Stephan’s Quintet, a frightening corner of the cosmos where five galaxies are locked in an ultimately fatal dance. 

Then there’s the spectral data of WASP-96 b — a really hot, giant, gassy exoplanet — which reveals the composition of its atmosphere in unprecedented detail. This one isn’t an image like you’d expect, but arguably something even more valuable. It’s a spectral dataset that helps us understand not what a spaceborne object aesthetically looks like but rather what it’d be like to stand on it. And, as they say, the book is often better than the film.

Let’s break down each one and explain why the JWST’s second batch of cosmic goodies is just as groundbreaking as its first peek.

The nebulas

Nebulas are immense clouds of dust and gas that exist at either end of a star’s life. Some are home to fledgling baby stars, while others are created by their explosive deaths. But in both cases, nebulas are responsible for some of the most stunning visuals we have of our cosmos — and through the JWST’s lens, the most powerful infrared imager we’ve ever worked with, their marvel is only enhanced. 

You can read exactly how the JWST’s infrared imaging works here, but the basic principle is it can access light — emanating across the cosmos from stars, galaxies and other luminescent objects — that’s stuck in a region of the electromagnetic spectrum invisible to our eyes. And more specifically to nebulas, that “hidden” light, so to speak, happens to be the main kind shooting through their dust clouds from whatever lies inside. 

That means our pupils, and even massive telescopes like the Hubble Space Telescope, can’t penetrate nebular curtains of gaseousness. They’re veils that typically obscure our view of…



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