Space and Physics
PUBLISHED
Without a mission around Saturn like Cassini, we can’t get close-up studies of the planet anymore. That said, the Hubble Space Telescope has been keeping an eye on the Lord of the Rings for years, tracking the changing seasons on its hemispheres and the position of the rings. Now this work, combined with observations from JWST, has revealed a lot more of what's happening on the gas giant planet.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.Hubble and JWST see the universe in different wavelengths. JWST uses infrared, and this allows it to peer deeper into the atmosphere of Saturn. Together, these observations, which are part of a decade-long monitoring program called OPAL (Outer Planet Atmospheres Legacy), revealed a three-dimensional view of the atmosphere.
The observations were a few months apart. The Hubble ones are from August 22, 2024, and show not just the different bands in the atmosphere but also three small and very faint moons: Janus, Mimas, and Epimetheus. JWST's observations were conducted as part of the director's discretionary time and took place in November 2024. That’s a few months before the disappearance of the rings as the planet and Earth entered their periodic alignment.
From Hubble, where the color variation hints at the deeper sources of changes inside Saturn, we can jump to the JWST insights. The planet was approaching the equinox when the observations were taken. The northern summer was ending, and the Southern Hemisphere was entering spring.
In the JWST data, we see the distinct pointed edges of Saturn’s hexagonal jet stream at the north pole, a puzzlingly shaped storm that also changes colors with the season. The grey-green appearance of both poles has nothing to do with that phenomenon. It is possible that these are high-altitude aerosols or even aurorae.
The telescope also brings into focus the giant ribbon wave that meanders at mid-latitudes of the planet, and right underneath, a small spot – the last remainder of the Great Springtime Storm of 2011. For more storms, you ought to look at the Southern Hemisphere. None of them look enormous, but there are two visible at a glance, so hopefully we’ll see more activity there over the coming years as the southern part of the planet goes into summer.
JWST too sees more than just the planet, bringing different moons into focus. Janus is spotted once again, together with Dione and little Enceladus, one of the most promising places for life outside of Earth.
The telescope also allowed us to see subtleties in the rings, from the famous spokes and structure in the B ring (the thick central region of the rings) to actually showing off the thin F ring. Hopefully, this won’t be just a one-off collaboration between the telescopes to track the changing weather on the outer planets.
