APOD: 2024 August 25 – Fresh Tiger Stripes on Saturns Enceladus

Good morning, Rallypoint, and welcome to the August 25th edition of Astronomy Picture of the Day (APOD). British astronomer William Herschel spotted Enceladus orbiting Saturn on Aug. 28, 1789. The name 'Enceladus' was taken from Greek mythology and suggested John Herschel (William's son) in 1847.

The 'tiger stripes' are believed to be caused by relatively warm fractures in the icy crust of Enceladus. In 2005, NASA’s Cassini spacecraft discovered that icy water particles and gas gush from the moon’s surface at rates of ~400 meters per second, and do so especially at its south pole. This creates a plume around Enceladus, and data gathered by Cassini found this plume to contain water vapor, carbon dioxide, methane, salts, and small particles of silica.

On Earth, silica is generated where liquid water and rock interact at temperatures above about 200 degrees Fahrenheit (90 degrees Celsius). Are there hydrothermal vents deep beneath Enceladus’ icy shell? They certainly dot Earth’s ocean floor. Is there an ocean lying beneath the ice? From gravity measurements based on the Doppler effect and the magnitude of the moon’s very slight wobble as it orbits Saturn, scientists believe that there could be. With a possible ocean, unique chemistry and internal heat, Enceladus has become a promising lead in our search for worlds where life could exist.