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The Galilean Moons of Jupiter Image Credit: NASA Planetary Photojournal

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Astronomy Name Game by Jamie Binkley

Ever wonder how the planets and moons are named? Who chooses the names and how do those titles they become official?

We can trace the history of the names of planets, moons, craters, asteroids, comets, and their features beginning in the late 1500’s when naming of astronomical bodies was unregulated and disorganized to today where we have an official organization dedicated to titling space objects in a systematic, traditional manner.  To identify, remember and talk about things, we give them names. In the beginning of our discoveries in space, scientists historically were responsible for the naming of such objects. The names chosen had a common theme and were first based on Roman mythology and later Greek mythology as well.  What happened when two astronomers discovered the same object and name them differently? This indeed occurred with four moons of Jupiter when Galileo and Simon Marius each dubbed the moons separately. In the end, it was Marius’ choices (suggested by Johannes Kepler) which we call them today – Io, Europa, Ganymede and Callisto.  Problems such as double naming were eliminated in 1919 when the International Astronomical Union (IAU) was founded. In the inaugural meeting, members created a committee to name planets and satellites which is now known as the Working Group for Planetary System Nomenclature. As of November 2012, they have officially named over 15,000 objects in space.  The IAU bases the nomenclature on a variety of topics – themes, Latin, traditional, historical people, musicians, writers, poets, scientists. Only comets and asteroids may be named after a person living; however, they may not be a political figure.

Today, the IAU officially brands names for planetary objects and satellites as well as other astronomical objects chosen carefully based on themes and tradition. They transformed the nomenclature of our solar system from chaotic and disorganized to regulated and orderly.


1. Shatner’s mission: To name Pluto moon after Vulcan. South Florida sun-sentinel. 2013 February 23.

2 Faircloth K. Don’t You DARE Try to Name Pluto’s Moons After Some Internet Nonsense. New York Observer, The (NY).

2013 February 11.

3 Lopes R. From Handel To Hydra: Naming Planets, Moons & Craters. Sky & Telescope. 2012 November:28-33.

4 Nature. The name game. Nature. 2012 August 23;488(7412):429.