planetary geology Planetary geology, alternatively known as astrogeology or exogeology, is a planetary science discipline concerned with the geology of celestial bodies such as planets and their moons, asteroids, comets, and meteorites. Although the geo- prefix t ...

, a corona (plural: coronae ) is an

oval An oval () is a closed curve in a plane which resembles the outline of an egg. The term is not very specific, but in some areas of mathematics (projective geometry, technical drawing, etc.), it is given a more precise definition, which may inc ...

-shaped feature. Coronae appear on both the planet

Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...

and

Uranus Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...

's moon Miranda and may be formed by upwellings of warm material below the surface.

Coronae on Venus

The geodynamic surface of Venus is dominated by patterns of basaltic volcanism, and by compressional and extensional tectonic deformation, such as the highly deformed tesserae terrain and the concentrically-fractured coronae. On Venus, coronae are large (typically several hundred kilometres across), crown-like, volcanic features. Coronae were first identified in 1983, when the

radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

imaging equipment aboard the Venera 15 and Venera 16 spacecraft produced higher-resolution images of some features previously thought to be impact craters. It is believed that coronae are formed when plumes of rising hot material in the mantle push the crust upwards into a dome shape, which then collapses in the centre as the molten magma cools and leaks out at the sides, leaving a crown-like structure: the corona. The largest corona on

is the Artemis Corona, which is 2100 km in diameter.

Coronae on Miranda

The small Uranian ovoid features coronae that are very large in relation to its size. They may be formed by diapirs: upwellings of warm ice. Three coronae are known on Miranda: Arden Corona, Elsinore Corona, and Inverness Corona.{{cite web , title=Miranda: Corona, coronae , publisher=USGS, Gazetteer of Planetary Nomenclature , url=https://planetarynames.wr.usgs.gov/SearchResults?Target=98_Miranda&Feature%20Type=8_Corona,%20coronae , access-date=5 June 2024

Notes

Surface features of bodies of the Solar System Planetary geology