Editing Hyperion (moon) (section)

=== Surface features ===

{{See also|List of geological features on Hyperion}}

''[[Voyager 2]]'' passed through the Saturn system, but photographed Hyperion only from a distance. It discerned individual craters and an enormous ridge, but was not able to make out the texture of Hyperion's surface. Early images from the ''[[Cassini–Huygens|Cassini]]'' orbiter suggested an unusual appearance, but it was not until ''Cassini'''s first targeted flyby of Hyperion on 25 September 2005 that Hyperion's oddness was revealed in full.

Hyperion's surface is covered with deep, sharp-edged [[impact crater|crater]]s that give it the appearance of a giant sponge. Dark material fills the bottom of each crater. The reddish substance contains long chains of [[carbon]] and [[hydrogen]] and appears very similar to material found on other Saturnian satellites, most notably [[Iapetus (moon)|Iapetus]]. Scientists attribute Hyperion's unusual, sponge-like appearance to the fact that it has an unusually low density for such a large object. Its low density makes Hyperion quite porous, with a weak surface gravity. These characteristics mean impactors tend to compress the surface, rather than excavating it, and most material that is blown off the surface never returns.<ref name="next2015"/>

The latest analyses of data obtained by ''Cassini'' during its flybys of Hyperion in 2005 and 2006 show that about 40 percent of it is empty space. It was suggested in July 2007 that this [[porosity]] allows craters to remain nearly unchanged over the eons. The new analyses also confirmed that Hyperion is composed mostly of water ice with very little rock.<ref>
{{cite web
 |title=Key to Giant Space Sponge Revealed
 |url=http://www.space.com/scienceastronomy/070704_sponge_moon.html
 |work=[[Space.com]]
 |date=4 July 2007
 |access-date=October 26, 2007
}}</ref>