The James Webb telescope has finally captured all four giant worlds in our solar system. The JWST observations of the ringed planet taken on June 25, 2023 have been cleaned and processed, giving us a spectacular view of Saturn’s magnificent rings glowing gold in the dark. By contrast, Saturn’s disk in the new image is quite dark, lacking the characteristic cloud bands and appearing a relatively indistinct dull brown.
This is due to the wavelengths in which JWST sees the Universe – near and mid-infrared. These wavelengths of light are usually invisible to the naked human eye, but they can reveal a lot. For example, thermal radiation associated with heat is dominated by infrared waves. When you’re trying to learn what’s going on inside a planet shrouded in thick, opaque clouds, studying its temperature is a valuable way to do so.
Some elements and chemical processes also emit infrared light. So seeing the planets of the solar system at wavelengths outside the narrow range that our vision allows can tell us a lot more about what’s going on with them.
Saturn
As we saw last week when we looked at JWST’s raw images of Saturn, the observations included filters that dimmed the planet’s light, allowing the light from the rings and moons to shine brightly. This is necessary so that the team led by planetary scientist Lee Fletcher from the University of Leicester in Great Britain could study Saturn’s rings and moons in more detail.
They hope to discover new ring structures and possibly even young moons orbiting the gas giant. The image above shows Saturn’s three moons, Dione, Enceladus, and Tethys, to the left of the planet. Although the planet’s disk is dim, it also reveals information about Saturn’s seasonal changes.
The Northern Hemisphere is nearing the end of its 7-year summer, but the polar region is dark. The cause may be an unknown aerosol process. Meanwhile, the atmosphere around the edges of the disk appears bright, which could be the result of methane fluorescence, or trihydrogen luminescence, or both. Further analysis can tell us which ones.
Jupiter
Jupiter was the first of the giant planets to get the JWST treatment, with images released last August – and hey, they’re stunning. The impressive detail seen in the planet’s storm clouds and storms may not have been entirely surprising, but we also saw some rarely seen features: the persistent auroras that flicker at Jupiter’s poles, invisible at optical wavelengths, and Jupiter’s thin rings.
We also saw two of the planet’s smaller, lesser-known moons, Amalthea and Adrasthea, with faint smudges of distant galaxies in the background.
“This single image summarizes the science of our Jupiter System Program, which studies the dynamics and chemistry of Jupiter itself, its rings and its satellite system,” said astronomer Thierry Fouche of the Paris Observatory in France, who led the observations.
Neptune
Neptune sightings arrived in the second half of September 2022. Because Neptune is so far away, it tends to get a little overlooked; You’re probably used to seeing the images taken by Voyager 2 when it flew by in 1989. JWST’s observations have given us a new look at the ice giant’s exquisite rings for the first time in more than 30 years – and for the first time in the infrared.
It also discovered seven of Neptune’s 14 known moons and bright spots in its atmosphere. Most of it is storm activity, but if you look closely, you’ll see a bright band surrounding the planet’s equator. This has never been seen before and, scientists say, may be a sign of Neptune’s global atmospheric circulation.
Uranus
Uranus is also pretty far away, but it’s also a huge oddity. Although the planets are very similar to Neptune, they have slightly different shades, which is a bit of a mystery, and Uranus is also turned sideways, which is also difficult to explain. The JWST observations, released in April 2023, don’t solve these mysteries, but they did reveal 11 of the 13 structures in Uranus’ incredible ring system and a puzzling atmospheric illumination above the planet’s polar cap.
JWST has a lot to say about the early universe; but it also brings space science close to home. As the first year of operation comes to an end, we can’t help but wonder what new wonders will appear in the coming years.
