This year marked the end of a decades-long wait for astronomers. The James Webb Space Telescope is finally in action.
The telescope, which was launched in December 2021, has released its first scientific data in July (SN: 8/13/22, p. 30) and immediately began to exceed astronomers’ expectations.
“We realized that James Webb is 10 times more sensitive than expected” for certain types of observations, explains astronomer Sasha Hinkley of the University of Exeter in England. His team published in September the first of the telescope direct image of an exoplanet (SN: 9/24/22, p. 6). He credits “the people who worked so hard to get it right, to launch something the size of a tennis court into space on a rocket and make that sensitive machinery work perfectly. And I feel incredibly lucky to be the beneficiary.
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The telescope, also known as JWST, was designed see further into the history of the cosmos than ever before (SN: 9/10/21 and 23/10/21, p. 26). It is larger and more sensitive than its predecessor, the Hubble Space Telescope. And because it looks into much longer wavelengths of light, JWST can observe distant, veiled objects that were previously hidden.
The JWST spent its first few months collecting “early” scientific data, observations that test the different ways the telescope can see. “It’s a very, very new instrument,” says Lamiya Mowla, an astronomer at the University of Toronto. “It will take some time before we can characterize all the different observing modes of the four instruments that are on board.”
This need for testing and the excitement led to some confusion for astronomers in those heady early days. Data from the telescope had been in such demand that operators had not yet calibrated all of the detectors before releasing the data. The JWST team provides calibration information so that researchers can properly analyze the data. “We knew calibration issues were coming,” says Mowla.
The raw numbers the scientists extracted from some of the initial images might end up being slightly revised. But the images themselves are real and reliable, even if it takes a bit of art translate infrared data from the telescope into colored visible light (SN: 3/17/18, p. 4).
The stunning photos that follow are some of the first big hits from the shiny new observatory.
JWST has captured the deepest views of the universe (above). The galaxy cluster SMACS 0723 (bluer galaxies) is 4.6 billion light-years from Earth. It acts like a giant cosmic lens, allowing the JWST to zoom in on thousands of even more distant galaxies that shone 13 billion years ago (the reddest and most stretched out galaxies). Distant galaxies look different in mid-infrared light (top left) captured by the telescope’s MIRI instrument than in near-infrared light (top right) captured by NIRCam. The first tracks the dust; the second, starlight. The first galaxies had stars but very little dust.
Rings around Neptune
JWST was designed to peer across vast cosmic distances, but it also offers new insights into our neighbors in the solar system. This picture of Neptune was the first close look at her delicate rings in over 30 years (SN: 11/5/22, p. 5).
The rings in this amazing image are not an optical illusion. They are made of dust and a new ring is added every eight years as the two stars in the center of the image come together. One of the stars is a Wolf-Rayet star, which is in the final stages of its life and is puffing up dust. Cyclic dusty eruptions allowed scientists to directly measure for the first time how pressure from starlight pushes dust around (SN: 11/19/22, p. 6).
Galaxy Hit and Run
With JWST’s unprecedented sensitivity, astronomers plan to compare early galaxies with more modern galaxies to understand how galaxies grow and evolve. This galactic smashup, the main remnant of which is known as the wheel galaxyshows one step in this epic process (SN online: 03/08/22). The large central galaxy (right in the composite above) has been punctured in the middle by a smaller one that has fled the scene (not visible). The Hubble Space Telescope previously captured a visible-light image of the scene (upper half). But with its infrared eyes, JWST revealed much more structure and complexity inside the galaxy (lower half).
Portrait of exoplanet
The gas giant HIP 65426b was the first exoplanet to have its portrait taken by JWST (each inset shows the planet in a different wavelength of light; the star symbol shows the location of the planet’s parent star). This image, posted by astronomer Sasha Hinkley and colleagues, doesn’t look like much compared to some of the JWST’s other spectacular views from space. But it will give clues to the composition of the planet’s atmosphere and show the telescope’s potential to do more of this kind of work on even smaller, rockier exoplanets (SN: 9/24/22, p. 6).
Shake off the dust
Another classic Hubble image updated by JWST is the Pillars of Creation. When Hubble viewed this star-forming region in visible light, it was shrouded in dust (top left). JWST’s infrared vision reveals sparkling newborn stars (top right).