Who Names the Planets?

The planets in the Solar System were named after figures from ancient Greek and Roman mythology. Venus is named after the Roman goddess of love and beauty, Mars after the Roman god of war, Uranus after the Greek god of the sky, and so on. However, modern science has discovered thousands of planets beyond the Solar System. Who names these planets? Sergey Popov (ICTP, Trieste) answers this question.

The only organization with the right to give official names to newly discovered planets and other astronomical bodies and their surface features is the International Astronomical Union (IAU). The IAU has held several public campaigns for naming exoplanets. The first campaign, NameExoWorlds, was organized in 2015 in collaboration with the Institute of Electrical and Electronics Engineers (IEEE). The campaign aimed to engage the public in astronomy by allowing people to propose names for selected exoplanets and their stellar systems. The second similar campaign, IAU100 NameExoWorlds, was held in 2019 to celebrate the IAU’s centenary; another similar contest was held in 2022.

However, the names proposed by the IAU did not become popular either in science (which is not too surprising) or in popular science, which might have been expected. Professionals and, following them, amateurs prefer to keep the technical names of objects. Such a name usually consists of three parts. The first part is the project’s name within which the planet was discovered. For example, if it were found using the Kepler satellite, the first part of the name would correspond. Next comes the ordinal number of the star around which the planet was discovered—Kepler-452. Finally, the last part is any Latin letter, starting with the letter b, chosen by the researchers. Kepler-452b is the first exoplanet discovered in the Kepler-452 star system by the Kepler satellite.

In some cases, the discoverers may give the planets unofficial nicknames. The fate of such nicknames varies. For example, the first discovered planet in a binary star system was Tatooine, after the planet with a similar feature in “Star Wars.” This name caught on and is often used.