28 August

1789: On 28 August 1789, Sir William Herschel discovered Saturn's moon Enceladus.

Enceladus is one of the innermost moons of Saturn. It reflects almost 100 percent of the sunlight that strikes it and has at least five different types of terrain. Parts of Enceladus have craters no larger than 35 kilmetres in diameter and other areas show regions with no craters, indicating major resurfacing events in the geologically recent past. This indicates that the interior of the moon may be liquid today, even though it should have frozen long ago. It is postulated that Enceladus is heated by a tidal mechanism.