Webb & Hubble capture new views of Saturn
The NASA‑ESA‑CSA James Webb Space Telescope and the NASA‑ESA Hubble Space Telescope have jointly captured new images of Saturn, delivering complementary infrared and visible‑light views of the planet’s atmosphere and rings. Hubble recorded its image in August 2024 as part of the Outer Planet Atmospheres Legacy (OPAL) monitoring program, while Webb obtained a follow‑up picture a few months later using Director’s Discretionary Time, the two observations being spaced by roughly fourteen weeks. Both telescopes observed the sunlit side of Saturn as the planet moved from northern summer toward the 2025 equinox, providing the most recent high‑resolution view of the gas giant’s northern pole before it enters a fifteen‑year winter darkness.
Webb’s infrared sensors detected cloud layers and chemical signatures at multiple atmospheric depths, ranging from deep convective clouds to the tenuous upper haze, and highlighted a long‑lived jet stream called the “ribbon wave” across the northern mid‑latitudes. A small bright spot in the same region corresponds to a lingering remnant of the 2011‑2012 Great Springtime Storm, while several southern‑hemisphere storms appear as distinct infrared features. Both observatories captured faint edges of Saturn’s hexagonal jet stream at the north pole, a structure first identified by Voyager in 1981, and Webb’s 4.3‑micron data showed the poles as grey‑green, suggesting high‑altitude aerosols or auroral emissions. The rings appear extremely bright in Webb’s image due to highly reflective water‑ice particles, with the B ring’s spokes and structure differing from Hubble’s view, and the outer F ring showing a thin, crisp outline in infrared versus a faint glow in visible light. The observations were enabled by the international partnership that built Webb, with ESA providing the Ariane 5 launch service, the NIRSpec spectrograph, and half of the MIRI mid‑infrared instrument, while NASA and CSA contributed additional hardware and operations.
The combined data extend OPAL’s multi‑year record of Saturn’s atmospheric evolution, adding infrared depth profiling to a legacy of visible‑light monitoring that has tracked storms, banding patterns, and seasonal changes for over a decade. The images represent the last detailed visual of the hexagon expected until the 2040s, underscoring the importance of the current dataset for studying fluid dynamics under extreme planetary conditions. Continued joint observations by Webb and Hubble will monitor Saturn’s transition into southern spring and later summer, refining models of giant‑planet weather systems and informing future missions that rely on precise atmospheric characterisation.
