James Webb Space Telescope: An astronomer describes the first stunning and newly released images

The James Webb Space Telescope Team has released the first scientific-quality images of the new telescope. It contains the oldest galaxies ever seen by the human eye, evidence of the presence of water on a planet 1,000 light years away and incredible detail showing the birth and death of stars. Webb’s goal is to explore the origins – the universe, galaxies, stars and life – and the five images released on July 12, 2022, fulfill that promise.

Once the instruments on board were cool and running smoothly, astronomers wasted no time getting Webb to work. Each first image contains sufficient data to produce its own primary scientific result.

Webb was designed to collect light across the red to mid-infrared spectrum – the wavelengths of light that are blocked by Earth’s atmosphere. And with giant mirrors and shielding the infrared rays emitted by the Sun, Earth and Moon, Webb can produce images with a sharpness never before achieved by other telescopes.

Rumors among professional astronomers like myself have been electrifying ever since members of the Webb team shared tantalizing test images. And the original image was even better than anyone expected. During the presentation in which the first images were released, Webb’s project scientist Jane Rigby said “for Webb there is no empty sky, everywhere we see distant galaxies.” Most of those galaxies were not visible until now.

This photo shows a gravitational lens and many bright galaxies, but the smaller, fainter, and less clear galaxies in this image are some of the oldest light ever detected by a man-made object.
NASA/STScI

Ancient galaxies and early universe

The first Webb image the world saw was of the galaxy cluster known to astronomers as SMACS 0723. It is located in the southern hemisphere sky and is 5.12 billion light years from Earth.

The detail of the thousands of individual galaxies in the images is simply stunning. It’s like the universe in high definition, and I encourage you to look at the full resolution images and zoom in to really appreciate the details.

The large white galaxies in the center of the image belong to the cluster and are similar in age to the Sun and Earth. The galaxies that surround and are interspersed between galaxy clusters are those that are more distant, but stretch into spectacular arcs as if seen through a magnifying glass. And that is what is happening. The background galaxy is much farther from Earth but appears magnified, because its light is deflected toward Earth by the gravity of the closer cluster.

In the background you can see a faint red galaxy scattered like rubies in the sky. The galaxies are even further away. By measuring the exact attributes of their light, astronomers can tell that they formed more than 13 billion years ago and even determine the abundances of different elements in these early galaxies.

Not only did Webb produce extremely sharp images, but they did so with ease when compared to its predecessor, the Hubble Space Telescope, launched in 1990. As Rigby puts it, “… the Hubble Extremely Deep Field took two weeks of exposure, Webb went deeper before breakfast.” After Webb makes longer observations that will allow him to gather more light from fainter stars or galaxies, astronomers will be able to see some of the first stars and galaxies to form just after the Big Bang.

The James Webb Space Telescope is sensitive enough to not only detect light passing through the atmospheres of distant planets, but also to measure the strength of this light at different wavelengths – as shown here – that could indicate the presence of water or other molecules in an atmosphere.
NASA/STScI

Understanding planets around other stars

The second disclosure is not an image but a spectrum – a breakdown of the strength of light at different wavelengths.

Webb pointed his mirror at the exoplanet WASP 96-B – a giant hot gas planet orbiting a star about 1,000 light-years from Earth – as it passed in front of its parent star. During this transit, some of the star’s light is filtered through the planet’s atmosphere and leaves a “chemical fingerprint” in its unique light spectrum. This specific fingerprint strongly indicates that there is water vapor, clouds and fog in WASP 96-B’s atmosphere.

As Webb moves to observe smaller planets that could potentially harbor life, astronomers hope to detect fingerprints of oxygen, nitrogen, ammonia, and carbon in the form of methane and other hydrocarbons. The goal is to find the biosignatures of life – that is, the chemistry that leads to an atmosphere modified by living organisms.

The technical challenge of making this type of observation, called transit spectroscopy, is enormous, and these early results barely scratch the surface of the scientific content of the spectrum.

The fine details seen in this image of the Carina Nebula offer clues as to how stars are born.
NASA/STScI

Galaxy dance and star life

The last three images show the incredible resolution of Webb’s optics as the telescope explores the birth and death of stars.

Webb’s ability to capture light in the mid-infrared range allows his camera to penetrate dense clouds of dust and gas. This ability helped Webb to capture spectacular details of the Carina Nebula where stars are born.

The Webb telescope can take images at a much higher resolution than other space telescopes, as shown in a side-by-side comparison of photos of a dying star with the Webb image on the left and the Hubble Space Telescope image on the right.
NASA/STScI

Webb is also very well suited to studying the end of a star’s life. As stars age, they can puff out their outer layers and form nebulae such as the stunning Southern Ring Nebula, imaged by Webb. The image reveals never-before-seen detail of successive waves of matter ejected by a dying central star. While Hubble was unable to see through the expanding cloud of dust and debris, Webb provided the first look at the binary star systems that make up the nebula.

The final photo from Webb’s exit party shows Stephan’s Quintet, a cluster of five galaxies 300 million light years from Earth, interacting in a cosmic dance. Thanks to a complementary set of instruments aboard Webb, telescopes can simultaneously pick up details of individual stars in this galaxy, see the cold dust and star formation that fuels the gas within this galaxy and – most remarkably – blocks out stars, gas and dust from seeing matter. circling around the supermassive black hole at the center of one of the galaxies.

Webb also captured data on the spectra of hundreds of individual star-forming regions in Quintet, which would take months to analyze and study.

Webb is the result of 25 years of work by thousands of scientists, engineers, and administrators who are part of an international collaboration of space agencies, companies, research centers, and universities around the world. John Mather, a project lead for Webb, emotionally describes the journey: “It’s been hard to do. It’s hard to express how difficult this is. There are a thousand ways it could go wrong.”

But it’s not wrong. It all came together, and now humanity’s largest space telescope is open for business.

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