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Astronomers have discovered surprising details about Saturn’s atmosphere, using a new image captured by NASA’s James Webb Space Telescope.
In the image, Saturn itself appears extremely dark due to the near-total absorption of sunlight by methane gas. The rings, however, remain bright, creating the “unusual appearance” of the planet in this photo, according to NASA.
Saturn’s moons Dione, Enceladus and Tethys dot the left side, while the Cassini division, Encke gap and rings A, B, C and F are shown on the right side. The Cassini division is the largest of the gaps in Saturn’s ring system.
The near-infrared observations of the ringed planet are a first for the highly sensitive telescope, according to NASA — which, at 1.5 million kilometers (nearly 932,000 miles) from Earth, observes the universe with wavelengths of light longer than those of other space telescopes.
The image was taken with Webb’s Near-Infrared Camera, known as NIRCam, as part of a Webb program that involves several exceptionally deep exposures of Saturn, according to NASA. These exposures test Webb’s ability to spot faint moons around the planet and its rings, since any newly discovered moons could help scientists better understand Saturn’s present and past systems.
Unexpectedly, “the large, diffuse structures in the northern hemisphere do not follow the planet’s lines of latitude, so this image is lacking the familiar striped appearance that is typically seen from Saturn’s deeper atmospheric layers,” according to NASA.
Differences in the looks of Saturn’s northern and southern poles are normal, according to NASA, as the northern region experiences summertime while the southern hemisphere is exiting winter darkness. But the darker-than-usual appearance of the northern hemisphere could be from “an unknown seasonal process affecting polar aerosols in particular,” NASA says.
The brightening near the edge of Saturn’s disk might be due to high-altitude methane fluorescence (the process of emitting light after absorbing light) or emissions in the planet’s ionosphere or both.
Further explorations of Saturn
Launched on Christmas Day in 2021, Webb can study the beginning of time more closely, hunt for unobserved formations among the first galaxies, and peer inside dust clouds where stars and planetary systems are currently forming.
This latest detailed image comes just weeks after the Webb telescope spotted a record-breaking water plume erupting from Saturn’s moon Enceladus, which feeds Saturn’s diffuse E ring, according to NASA.
Over the years, Saturn’s atmosphere and rings have been observed by other missions such as NASA’s Pioneer 11, Voyagers 1 and 2, the Cassini spacecraft and the Hubble Space Telescope. In the future, additional and deeper exposures from Webb will help astronomers examine fainter rings around Saturn, according to NASA.
These new observations from the Webb telescope “are just a hint at what this observatory will add to Saturn’s story in the coming years,” NASA says, “as the science team delves deep into the data to prepare peer-reviewed results.”