As Christmas approached last year, astronomers and space fans around the world gathered to watch the long-awaited launch of the James Webb Space Telescope. Although a marvel of engineering, the telescope was not without its controversies, from being way over budget and behind schedule to being named after a former NASA administrator who was accused of homophobia.
Despite the debate over the telescope’s name and history, one thing has become abundantly clear this year — JWST’s science capabilities are remarkable. Beginning its scientific operations in July 2022, it has already allowed astronomers to gain new views and unravel mysteries about a vast array of space topics.
JWST’s most pressing goal is one of the most ambitious projects in the recent history of astronomy: to look back at some of the first galaxies that formed when the universe was very young.
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 forming more than 13 billion years ago.
Although there was some debate among astronomers about the accuracy of some of the first detections of early galaxies—JWST’s instrument wasn’t fully calibrated, so there was some wiggle room about exactly how old the most distant galaxies were—recent findings support the idea that JWST has spotted galaxies since the first 350 million years after the Big Bang.
This makes these the earliest galaxies ever observed, and they had some surprises, such as being much brighter than expected. This means there is still more to learn about how galaxies formed in the early universe.
These early galaxies are identified using surveys and deep field imaging that use Webb to look at large patches of sky that might appear empty at first glance. These areas lack bright objects like the planets of the Solar System and are located far from the center of our galaxy, allowing astronomers to look deep into 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 the planet WASP-39b, including water vapor and sulfur dioxide. Not only does this mean scientists can see the composition of the planet’s atmosphere, but they can also see how the atmosphere interacts with light from the planet’s host star, as sulfur dioxide is created by chemical reactions with light.
Learning about exoplanet atmospheres is critical if we ever want to find Earth-like planets and search for life. Previous-generation instruments can identify exoplanets and determine basic information such as their mass or diameter and how far they orbit from their star. But to understand what it would be like to be on one of these planets, we need to know about their atmospheres. With data from JWST, astronomers will be able to search for habitable planets far beyond our solar system.
Jupiter’s rings as seen 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 in the infrared, JWST was able to pick out features like Jupiter’s auroras and a clear view of its Great Red Spot. And the telescope’s high precision meant it could see small objects even against the brightness of the planets, such as showing Jupiter’s rarely seen rings. It also produced the clearest image of Neptune’s rings in more than 30 years.
Another major survey conducted by JWST this year was on Mars. Mars is the best-studied planet outside of Earth, having hosted numerous rovers, orbiters and landers over the years. This means that astronomers have a pretty good idea of its atmospheric composition and are beginning to learn about its weather system. Mars is also particularly difficult to study from a sensitive space telescope like JWST because it is so bright and so close. But these 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, showing the composition of its atmosphere almost perfectly matching the pattern expected from current data, showing how accurate JWST’s instruments are for this kind of study.
Another goal of JWST is to learn about the life cycle of stars, which astronomers currently understand in general terms. They know that clouds of dust and gas form knots that gather more material to them and collapse to form protostars, for example, but exactly how this happens needs more research. They also learn about the regions where stars form and why stars tend to form in clusters.
JWST is particularly useful for studying this topic because its infrared instruments allow it to peer through clouds of dust to see inside star-forming regions. Recent images show the development of protostars and the clouds they eject, and examine regions of intense star formation, such as the famous Pillars of Creation in the Eagle Nebula. By imaging these structures at different wavelengths, the JWST instruments can see different features of dust and star formation.
NGC 7469 ESA/Webb, NASA & CSA, L. Armus,
Speaking of the pillars of creation, one of JWST’s greatest legacies in the public mind 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’s images have been everywhere this year.
Besides the gorgeous Carina Nebula and the first deep field, other images worth taking a minute to marvel at include the star-sculpted shapes of the Tarantula Nebula, the dusty “tree rings” of the binary star Wolf-Rayet 140, and the otherworldly glow of Jupiter in the infrared.
And the images keep coming: just last week, a new image was released showing the brightly glowing heart of the galaxy NGC 7469.
Here’s to a year of amazing discoveries and many more to come.
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