Webb and Hubble Reveal Saturn's Atmosphere Layer by Layer

A Remnant Storm Caught in Infrared

One of the more striking features in the Webb infrared image is a small but distinct atmospheric spot — a remnant of the Great Springtime Storm that raged across Saturn's northern hemisphere between 2010 and 2012. That storm was one of the largest atmospheric events observed on any planet in the solar system during the space age, generating a disturbance that circled Saturn's entire northern hemisphere. Twelve years later, its fingerprint is still detectable in the thermal infrared, a testament to the depth and persistence of Saturnian weather systems.

The Rings in Infrared and Visible Light

Saturn's rings behave differently across the electromagnetic spectrum, and the combined imagery makes this contrast vivid. In Hubble's visible-light view, the rings appear as the familiar banded structure of gold and tan hues. In Webb's infrared, the same rings glow a bright icy neon white, a consequence of the high reflectivity of water ice — the primary composition of the ring particles — at near-infrared wavelengths.

Six of Saturn's moons appear in the images: Janus, Dione, Enceladus, Mimas, Epimetheus, and Titan. Enceladus, known to harbor a subsurface ocean and erupt water vapor through geysers at its south pole, is visible as a small bright point near the rings in the wide-field frame.

The Scientific Value of Multi-Wavelength Astronomy

The new Saturn observations exemplify the scientific strategy behind operating multiple complementary observatories simultaneously. Webb and Hubble were designed with different primary missions and different wavelength capabilities, but their simultaneous operation allows astronomers to combine their views in ways that reveal planetary structure with unprecedented depth. Webb's infrared sensitivity probes atmospheric layers that are opaque to visible light; Hubble's sharp visible-light resolution captures cloud structure and surface features with clarity that even Webb cannot match at those wavelengths.

The joint observation builds on the data legacy of the Cassini orbiter, which spent 13 years in orbit around Saturn before its deliberate atmospheric entry in September 2017. Cassini provided the most detailed in-situ characterization of Saturn's atmosphere, rings, and moons ever collected, and the Webb-Hubble observations extend that understanding by enabling systematic monitoring of the planet's weather and atmospheric evolution from Earth's orbital vicinity. With both telescopes in their prime operational years, astronomers expect to revisit Saturn periodically, building a time-series record of atmospheric dynamics that will inform models of giant planet weather for decades.

This article is based on reporting by science.nasa.gov. Read the original article.