Saturn

Saturn is the sixth planet from the Sun and the second-largest in the Solar System. Its defining feature — the spectacular ring system — is unique in scale among the planets and clearly visible through even small telescopes. The rings span up to 282,000 km in diameter but are less than 100 meters thick in most places.

Hubble observes Saturn at opposition (when Earth and Saturn are aligned on the same side of the Sun) each year as part of the Outer Planet Atmospheres Legacy (OPAL) program, building a multi-year record of atmospheric changes. These annual portraits capture evolving storm systems, seasonal color shifts, and changes in ring appearance as Saturn’s orbital tilt changes from Earth’s perspective.

The rings consist primarily of water ice particles ranging from microscopic grains to chunks several meters across. Their bright reflectivity makes Saturn disproportionately luminous for its distance. The Cassini Division — the prominent dark gap in the rings — is maintained by orbital resonances with the moon Mimas.

Saturn’s axial tilt of 26.7° means its rings appear at different angles over its 29.4-year orbit, alternately showing the northern and southern face to Earth observers.