Arachnoid (astrogeology)

In astrogeology, an arachnoid /əˈræknɔɪd/ is a large geological structure resembling a spider web. They are of unknown origin, and have been found only on the surface of the planet Venus. They appear as concentric ovals surrounded by a complex network of fractures, and can span 200 kilometers. Over 90 arachnoids have been identified on Venus.^[2]

Venusian arachnoid Trotula Corona^[1]

Arachnoids could be related to volcanos, however it is also possible that different arachnoids are formed by different processes.^[3] One possible explanation is that an upwelling of magma from the interior of the planet pushed up on the surface, causing cracks.^[4] An alternate theory concerning their origin is that they are a precursor to coronae formation.^[5]

Much of what is known about arachnoids is the result of studies performed by C.B. Dawson and L.S. Crumpler.^[6]

See also

• Chaos terrain
• Geysers on Mars
• Pancake dome
• Rille
• Coronae