How the James Webb Space Telescope changed astronomy in its first year

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As Christmas approached last year, astronomers and space enthusiasts around the world gathered to watch the highly anticipated launch of the James Webb Space Telescope. While a prodigious piece of engineering, the telescope wasn’t without its controversies — from way over budget and behind schedule to being named after a former NASA administrator who has been accused of homophobia.

Despite the debates over the telescope’s naming and history, one thing has become abundantly clear this year: JWST’s scientific prowess is remarkable. It began scientific operations in July 2022 and has already enabled astronomers to gain new insights and uncover mysteries about a huge range of space topics.

JWST’s most pressing goal is one of the most ambitious projects in recent astronomy history: looking back at some of the first galaxies that formed when the Universe was brand new.

Thousands of galaxies engulf this near-infrared image of galaxy cluster SMACS 0723

Because light takes time to travel from its source to us here on Earth, by looking at extremely distant galaxies, astronomers can actually look back in time to see the earliest galaxies formed more than 13 billion years ago.

While there was some debate among astronomers about the accuracy of some of the first detections of early galaxies – JWST’s instrument was not fully calibrated, so there was some leeway as to exactly how old the farthest galaxies were – recent findings have challenged the idea that JWST galaxies from the first 350 million years after the Big Bang.

That makes these among the earliest galaxies ever observed, and they had some surprises in store, such as being much brighter than expected. That means we can learn more about how galaxies form in the early universe.

These early galaxies are identified using surveys and deepfield images, which Webb uses to look at large areas of the sky that appear empty at first glance. These regions lack bright objects like planets in the solar system and are far from the center of our galaxy, allowing astronomers to peer into the depths of space to spot these extremely distant objects.

JWST was able to detect carbon dioxide in the atmosphere of an exoplanet for the first time and recently discovered a host of other compounds in the atmosphere of planet WASP-39b, including water vapor and sulfur dioxide. Not only does that mean scientists can see the composition of the planet’s atmosphere, but they can also see how the atmosphere interacts with the light from the planet’s parent star, as sulfur dioxide is created by chemical reactions with light.

Learning about exoplanet atmospheres is crucial if we are ever to find Earth-like planets and search for life. Previous generation tools can identify exoplanets and determine basic information such as their mass or diameter and how far they are from their star. But to understand what it would be like to be on one of these planets, we need to know their atmospheres. Data from JWST allows astronomers to search for habitable planets far beyond our solar system.

Jupiter's rings captured by the space telescope.

Jupiter’s rings captured by the space telescope.
Image: NASA

It’s not just distant planets that attract JWST’s attention. Closer to home, JWST has been used to study planets in our solar system, including Neptune and Jupiter, and will soon be used to study Uranus as well. By looking into the infrared range, JWST was able to discern features such as Jupiter’s auroras and a clear view of the Great Red Spot. And the telescope’s high accuracy allowed it to see small objects even against the brightness of the planets, such as Jupiter’s rarely seen rings. It also captured the clearest picture of Neptune’s rings in more than 30 years.

Another major survey JWST conducted this year was of Mars. Mars is the best-studied planet beyond Earth and has played host to countless rovers, orbiters, and landers over the years. That means astronomers have a pretty good understanding of the composition of the atmosphere and are starting to learn about the weather system. Mars is also extremely difficult to study for a sensitive space-based telescope such as JWST because it is so bright and so close. But those factors made it the perfect testing ground to see what the new telescope was capable of.

JWST used both its cameras and its spectrographs to study Mars and showed the composition of its atmosphere, which matched almost perfectly the model expected based on current data, showing how accurate JWST’s instruments are for this kind of research .

Another goal of JWST is to learn more about the life cycle of stars, which astronomers now broadly understand. They know that clouds of dust and gas form knots that gather more material and collapse to form protostars, for example, but exactly how that happens requires more research. They also learn about the regions where stars form and why stars tend to form in groups.

JWST is especially useful for studying this topic, because its infrared instruments make it possible to look through dust clouds to see areas where stars are forming. Recent images show the development of protostars and the clouds they shed and look at regions of intense star formation, such as the famous Pillars of Creation in the Eagle Nebula. By imaging these structures at different wavelengths, JWST instruments can see different features of dust and star formation.

This image shows a spiral galaxy dominated by a bright central region.  The galaxy has blue-purple hues with orange-red areas filled with stars.  Also visible is a large diffraction peak, appearing as a star pattern over the central region of the galaxy.  Many stars and galaxies fill the background scene

NGC 7469
ESA/Webb, NASA & CSA, L. Armus,

Speaking of the Pillars of Creation, one of JWST’s greatest legacies in the mind of the public is the stunning images of space it captured. From the international excitement at the unveiling of the telescope’s first images in July to new views of iconic landmarks like the Pillars, Webb images have been everywhere this year.

Besides the beautiful Carina Nebula and the first deep field, there are other images worth contemplating for a minute, such as the star-sculpted shapes of the Tarantula Nebula, the dusty “tree rings” of binary star Wolf-Rayet 140 and Jupiter’s alien glow in the infrared.

And the images keep coming: Last week, a new image was released showing the brightly glowing heart of galaxy NGC 7469.

This is a year full of incredible discoveries, with many more to come.

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