Line 2:
[[File:Memphis Facula.gif|right|thumb|''[[Voyager 2]]'' image of [[Memphis Facula]] (white patch at lower right) on [[Ganymede (moon)|Ganymede]]]]
A '''palimpsest''' {{IPAc-en|'|p|ae|l|ᵻ|m|p|s|E|s|t}}, in [[Planetary science|planetary astronomy]], is an ancient [[Impact crater|crater]] that has been degraded over time. They may also be referred to as "ghost craters", "degraded craters", or "pathological craters". PalimsestsPalimpsests have been identified on Mercury, the Earth, the Moon, Mars, Ganymede, Callisto, and possibly even Titan. On Mars, these features are morphologically described as craters that are "flat-floored, rimless, extremely shallow, without central peaks, and would probably represent what remains after erosion."<ref name=Barata_et_al_2012/>
On an [[icy moon]] of the [[Solar System#Outer Solar System|outer Solar System]], a palimsestpalimpsest is a crater whose [[relief]] has disappeared due to creep of the icy surface ("viscous relaxation") or subsequent [[cryovolcanic]] outpourings, leaving a circular albedo feature, perhaps with a "ghost" of a rim. [[Ice|Icy]] surfaces of natural satellites like [[Callisto (moon)|Callisto]] and [[Ganymede (moon)|Ganymede]] preserve hints of their history in these rings. A typical example is [[Memphis Facula]] on Ganymede, a 340 km wide palimpsest.<ref name=Harland2000/>
==See also==
|
Article Images