Saturn has been captured by the James Webb Space Telescope (JWST) as a ghostly sphere, its rings shining brighter than ever. Three of its moons, Dione, Tethys, and Enceladus, are also visible.
“Not a familiar sight of Saturn by any stretch of the imagination,” he says Leigh Fletcher at the University of Leicester, UK. “In the atmosphere, you don’t see the streaks that are characteristic of Saturn at the deepest levels, and that’s because this particular wavelength we chose is a wavelength at which methane gas in Saturn’s atmosphere it absorbs almost all the sunlight that falls on it. so it looks very, very dark.”
The image is based on near-infrared observations of the planet, and JWST’s infrared detectors, Fletcher hopes, will reveal small, faint features in Saturn’s atmosphere, rings and moons that previous missions missed, such as the Cassini spacecraft. Cassini last imaged Saturn in 2017, and since then the planet has begun tilting its rings toward Earth in a ridge formation as part of its 30-year orbit, with both poles receiving equal amounts of sunlight.
“It’s like the autumnal equinox we would have here on Earth, so it’s time to go and take another look at the Saturn system,” says Fletcher.
Saturn’s unusual appearance is also due in part to infrared-sensitive aerosols high in its stratosphere, giving the planet a splotchy appearance rather than its typical banded structure, Fletcher says. The brilliant white rings are the result of extremely reflective ice grains reflecting sunlight.
The image is a still exposure of Saturn, which Fletcher and his colleagues will use as a point of comparison to help them identify what’s what in subsequent images of the planet. It will also help them study a long exposure of Saturn and its surroundings, similar to a very short movie, so that smaller moving structures and objects, such as its smaller moons, can be identified.
