William Herschel discovers a new moon of Saturn: Enceladus.

Enceladus is the sixth-largest moon of Saturn and the 18th largest in the Solar System. It is about 500 kilometres in diameter, about a tenth of that of Saturn's largest moon, Titan. It is covered by clean, freshly deposited snow hundreds of meters thick, making it one of the most reflective bodies of the Solar System.

Consequently, its surface temperature at noon reaches only −198 °C, far colder than a light-absorbing body would be. Despite its small size, Enceladus has a wide variety of surface features, ranging from old, heavily cratered regions to young, tectonically deformed terrain.

PIA17202 - Approaching Enceladus
PIA17202 - Approaching Enceladus (Source: Wikimedia Commons)
William Herschel01
William Herschel01 (Source: Wikimedia Commons)
John F. Hershel
John F. Hershel (Source: Wikimedia Commons)
E ring with Enceladus
E ring with Enceladus (Source: Wikimedia Commons)

Watch: How Enceladus Shocked NASA Scientists - Secrets of Saturn’s Icy Moons | Space Documentary

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Sources and further reading: Wikipedia — Enceladus, William Herschel, Moons of Saturn (CC BY-SA). Images: Wikimedia Commons.