The New Horizons spacecraft, which flew past Pluto in 2015, successfully approached Ultima Thule, a Kuiper belt object on January 1, 2019. The name Ultima Thule means a distant unexplored place, which, although very suitable for a celestial body, is still just a nickname. The official name will be assigned by the International Astronomical Union, which turns 100 in 2019.
The Union's accomplishments include a selection of various names given to the geologic formations on the Moon and Mars by rival astronomers over the centuries. But the tasks of the organization did not end there - the space age began, and spacecraft began to send images to Earth showing elements of the landscape of planets and their moons.
Based on the already established lunar and Martian names, the International Astronomical Union has chosen themes for the names of geological formations on each celestial body. For example, large craters on Mars are named after deceased writers and scientists who were somehow associated with Mars (for example, Asimov and Da Vinci), and craters less than 60 km in diameter are named after cities and villages on Earth (for example, Bordeaux and Cadiz).
Aside from craters, most geological names are in two parts, with a descriptive term of Latin origin added to indicate a type of geological formation. On Mars, we can find valleys called Aris Vallis, Tiu Vallis and Simud Vallis (Vallis - Latin valley). Before the term, the name of Mars is added in another language - in these examples, in Greek, Old English / Germanic, and Sumerian. Other descriptive terms include Chasma (canyon), Mons (mountain), Planitia (low-lying plain), and Planum (high valley or plateau).
The largest volcano on Mars, Olympus Mons (Olympus) is sometimes seen from Earth as a short-lived bright spot that can sometimes be seen through telescopes. Although its first name was Nix Olympica (the snow of Olympus), the probes showed that the periodic changes in brightness are not snow, but clouds that sometimes gather at the summit. The International Astronomical Union decided to keep Olympus as part of the name, adding a more appropriate descriptive term Mons (Latin for mountain).
On the Moon, the Union left Mare (Latin sea) as a descriptive term for dark spots, although it is clear that they were never filled with water, as ancient astronomers believed. But Mare Langrenianum, named after the Dutch astronomer Michael van Langren in 1655, is now called Mare Fecunditatis.
The International Astronomical Union strives to achieve a cultural and gender balance in names. The names of the lunar craters, for example, have immortalized famous scientists of the past, who for historical reasons are mostly men from the West. As a partial compensation, the Union decided that all geologic formations on Venus, whose surface was unexplored due to global cloud cover until a radar spacecraft was launched into orbit, would be named after women. For example, Nightingale Corona is an oval landscape feature named after Florence Nightingale. There are three exceptions to non-feminine names that have been noticed since Earth.
Prior to the first detailed photographs of Jupiter's moons, which were made by Voyager 1 in 1979, the Union planned to use names from the myths of the peoples of the equatorial zone of the Earth for the moon Io, inhabitants of the European temperate zone for Europe, characters of Eastern mythology for Ganymede and the names of the gods of cultures of the extreme north for Callisto.
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The rule worked for the last three moons, for example, Europa has Annwn Regio (Annwn is the Welsh afterlife), Ganymede and Callisto have craters called Anubis and Valhalla.
But since it turned out that volcanic eruptions constantly occur on Io, the elements of the satellite's landscape began to be assigned the names of the deities of fire, sun, thunder, lightning and volcanoes of the peoples of the whole world. For example, Ah Peku, Camaxtli, Emakong, Maui, Shamshu, Tawhaki, and Tien Mu are the names of the fire, thunder or sun gods of the Maya, Aztec, tribes of New Britain, Hawaii, the Arabian Peninsula, Maori and China.