Einstein, Bremerhaven and Poltergeist – all of this can be found in space. Not only celestial bodies, but also geological and geographical features on their surfaces such as craters, mountains or boulders are given their own names. These are set by the International Astronomical Union (IAU), an association of more than 10,000 professional astronomers from all over the world.
“The naming is done to improve orientation and facilitate communication,” says Michael Khan, mission analyst at the European Space Operations Center (ESOC), the German Press Agency (dpa).
There are precise rules. Small structures on celestial bodies less than 100 meters in size must in most cases be of exceptional scientific interest. Terms with political, military or religious meaning are not allowed. Exceptions apply, for example, to politicians after their death or Roman gods. “This is to prevent politicians from immortalizing themselves in space,” explains Khan.
“The names must be generally pronounceable”
In addition, the designations must be unambiguous and be able to be used in different languages without any problems in order to avoid confusion between astronomers worldwide. “The names have to be universally pronounceable,” says Khan.
In principle, anyone can make suggestions. “Together with a justification, you can submit names to the IAU, which will then evaluate them in a commission,” explains Khan. If these are accepted by the IAU, they are entered into their database together with the location, the date of discovery and a brief explanation.
Some celestial bodies are divided into subject areas. On Mars, for example, the large craters are named after famous scientists (e.g. Helmholtz, Kepler or Wirtz), smaller craters after existing cities. Abandoned cities from antiquity are the inspiration for the valleys on Mercury.
The discoverers have the right to propose objects in space
Mostly female personalities and goddesses are recorded on Venus. Craters on the moon are named after scientists or discoverers from astronomy, planetary or space research. Rules also apply to the dark lowlands on the moon, formed from solidified lava – the so-called maria (plural of mare): “The maria are named after emotional moods or meteorological conditions,” explains Khan. One of the most famous is the Mare Tranquillitatis, the Sea of Tranquility.
In the same way, asteroids and comets as well as structures on their surfaces are given their own names. The discoverers have the right to suggest objects in space, and they often immortalize themselves. On the comet Churyumow-Gerasimenko (Tschuri for short), for example, which bears the names of its two discoverers, other terms follow the gods of Egyptian history, such as Anubis and Khepre.
Not everything in space is defined with its own term
On the Internet, some providers offer the purchase and naming of stars. “It’s not binding and is just printed paper that doesn’t say anything,” Khan says. The IAU is the only institution with the right to name celestial bodies. The organization has been cataloging proper names of stars since 2016 and currently has more than 400 star names.
In order to take into account people’s increased interest in astronomical discoveries and to involve a broad public, the IAU called for the first time in 2015 a global naming competition for some exoplanets and their home stars. These distant celestial bodies outside of our solar system usually only carry catalog numbers. Poltergeist, Galileo and Orbitar prevailed in the competition.
But not everything in the universe is defined with its own term. “Only large and permanent structures are named. This is difficult with the gas-ice giants Jupiter, Saturn, Uranus and Neptune,” emphasizes Khan in contrast to the rocky planets Mercury, Venus, Earth and Mars.
During the Rosetta mission, there were also changing components on comet Tschuri that were not given any special designation, reports Holger Sierks, who was involved in the space probe mission for the Max Planck Institute for Solar System Research.
Nevertheless, an end to the search for names in the universe is not in sight. “Space is always being explored, and more and more is being discovered that needs to be named,” says Khan. Only recently, in a third public competition, the IAU named more exoplanets and stars, including Wouri, Puli and Su.
