Magellan's Perspective View of Sedna Planitia, 45° N, 11° E

This perspective view of Venus, generated by computer from Magellan data and color-coded with emissivity, shows part of the lowland plains in Sedna Planitia. Circular depressions with associated fracture patterns called "coronae" are apparently unique to the lowlands of Venus, and tend to occur in linear clusters along the planet's major tectonic belts. Coronae differ greatly in size and detailed morphology: the central depression may or may not lie below the surrounding plains, and may or may not be surrounded by a raised rim or a moat outside the rim. The corona shown here is relatively small (~100 km in diameter and ~1 km deep) and is of the subtype known as an "arachnoid" because of the spider-like configuration of concentric (body) and radial (legs) fractures. Coronae are thought to be caused by localized "hot spot" magmatic activity in Venus' subsurface. Intrusion of magma into the crust first pushes up the surface, after which cooling and contraction create the central depression and generate a pattern of concentric fractures. In some cases, lava may be extruded onto the surface. The fractured ridge at the left is classified as a "nova" or "stellate fracture center" and is believed to represent an early phase of corona formation, in which subsidence due to cooling has not yet created the central depression, and the fracture pattern is still entirely radial. Magellan MIDR quadrangle* containing this image: C1-45N011. Image resolution (m): 225. Size of region shown (E-W x N-S, in km): 439 x 474. Range of emissivities from violet to red: 0.82 -- 0.88. Vertical exaggeration: 100. Azimuth of viewpoint (deg clockwise from East): 150. Elevation of viewpoint (km): 600. *Quadrangle name indicates approximate center latitude (N=north, S=south) and center longitude (East).