Tholus
Encyclopedia
In planetary geology
, tholus (pl. tholi) is the term used to describe a small domical
mountain
or hill
. The word is from the Greek θόλος, which means a circular building with a conical or vaulted roof. The Romans transliterated the word into the Latin tholus, which means cupola
or dome. In the early 1970s, the International Astronomical Union
(IAU) adopted tholus as one of a number of official descriptor terms for topographic features on Mars
and other planets and satellites. One justification for using neutral Latin or Greek descriptors was that it allowed features to be named and described before their geology
or geomorphology
could be determined. For example, many tholi appear to be volcanic in origin, but the term does not imply a specific geologic origin. Currently, the IAU recognizes 54 descriptor terms. (See Planetary nomenclature
.) Tholi are present on Venus
, Mars
, and on Jupiter's
moon Io
.
Planetary geology
Planetary geology, alternatively known as astrogeology or exogeology, is a planetary science discipline concerned with the geology of the celestial bodies such as the planets and their moons, asteroids, comets, and meteorites...
, tholus (pl. tholi) is the term used to describe a small domical
Dome
A dome is a structural element of architecture that resembles the hollow upper half of a sphere. Dome structures made of various materials have a long architectural lineage extending into prehistory....
mountain
Mountain
Image:Himalaya_annotated.jpg|thumb|right|The Himalayan mountain range with Mount Everestrect 58 14 160 49 Chomo Lonzorect 200 28 335 52 Makalurect 378 24 566 45 Mount Everestrect 188 581 920 656 Tibetan Plateaurect 250 406 340 427 Rong River...
or hill
Hill
A hill is a landform that extends above the surrounding terrain. Hills often have a distinct summit, although in areas with scarp/dip topography a hill may refer to a particular section of flat terrain without a massive summit A hill is a landform that extends above the surrounding terrain. Hills...
. The word is from the Greek θόλος, which means a circular building with a conical or vaulted roof. The Romans transliterated the word into the Latin tholus, which means cupola
Cupola
In architecture, a cupola is a small, most-often dome-like, structure on top of a building. Often used to provide a lookout or to admit light and air, it usually crowns a larger roof or dome....
or dome. In the early 1970s, the International Astronomical Union
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
(IAU) adopted tholus as one of a number of official descriptor terms for topographic features on Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
and other planets and satellites. One justification for using neutral Latin or Greek descriptors was that it allowed features to be named and described before their geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
or geomorphology
Geomorphology
Geomorphology is the scientific study of landforms and the processes that shape them...
could be determined. For example, many tholi appear to be volcanic in origin, but the term does not imply a specific geologic origin. Currently, the IAU recognizes 54 descriptor terms. (See Planetary nomenclature
Planetary nomenclature
Planetary nomenclature, like terrestrial nomenclature, is a system of uniquely identifying features on the surface of a planet or natural satellite so that the features can be easily located, described, and discussed. The task of assigning official names to features is taken up by the International...
.) Tholi are present on Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
, Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
, and on Jupiter's
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
moon Io
Io (moon)
Io ) is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of , the fourth-largest moon in the Solar System. It was named after the mythological character of Io, a priestess of Hera who became one of the lovers of Zeus....
.