Asgard (Callisto)

The Asgard impact basin is located on Callisto, the outermost of Jupiter's four large Galilean moons. Callisto is known for being one of the most heavily cratered objects in the entire solar system. Asgard is situated in the northern hemisphere of this icy moon.

The Asgard multi-ring structure is enormous, with its outermost rings stretching to a diameter of approximately 1,700 kilometers. This makes it one of the largest impact features in the solar system, comparable to the Valhalla basin, which is also on Callisto. The central bright spot, or palimpsest, is surrounded by dozens of concentric icy rings.

The crater was named after Asgard, the realm of the gods in Norse mythology. The International Astronomical Union names features on Callisto after characters and places from Norse mythology and other northern Eurasian myths. Other nearby features are named after figures like Valhalla and the god Odin.

The bright center of the Asgard basin is called a palimpsest, which is characteristic of large impacts on icy moons. When the massive meteorite hit, it penetrated Callisto's icy crust, causing fluid, slushy ice from below to well up and fill the crater. Over billions of years, this ice froze solid, creating a smooth, bright central patch.