Name that moon!


Public invited to suggest names for not one, but five satellites discovered orbiting Jupiter. Brian Pulling reports. 


Jupiter has many moons, some newly discovered and as yet unnamed.

Zenobillis/Getty Images

In July 2018, Scott Sheppard and his team at the Carnegie Institution for Science in Hawaii, US, announced the discovery of 12 Jovian moons – and the public have been invited to name five of them.

Suggestions can be submitted until April 15, 2019, by sending a tweet to @JupiterLunacy, with written or video recorded reasons for the name chosen.

Include the tag #NameJupitersMoons.

“I’m excited to get suggestions, and especially eager to see video suggestions, from the public for what these five moons should be named,” Sheppard says.

The astronomer is something of an exo-moon specialist, having discovered 60 of Jupiter’s currently recognised crop of 79 satellites.

He also discovered 25 of Saturn’s 62, two for Uranus and one for Neptune, along with 16 minor planets, a few comets, minor-planet moons, and assorted celestial objects.

Clearly an expert in finding things, but how does he do it?

“To discover a moon, you need to image the space around Jupiter to very faint depths,” he explains.

“Only the world’s largest telescopes can do this. But you also need a big field of view since the space around Jupiter is very large. Very few large telescopes have large field of view cameras.

“Once you actually discover an object that appears to be a moon of Jupiter, you need to re-observe the candidate over months and years to actually officially determine the orbit. Thus, it takes time to confirm and object is an actual moon of Jupiter.”

The rules for naming new celestial objects are described by the International Astronomical Union (IAU).

For the newly discovered Jovian moons, the organisation recently announced a change to the conventions governing the choice of names. Up until now, all the planet’s moons have been identified using the names of lovers or favourites of the Graeco-Roman god Zeus, or Jupiter.

For the latest batch, however, names deriving from the deity’s many descendants will also be considered. And that provides plenty of fresh choices.

There are at 259 lovers and direct descendants of Jupiter/Zeus. According to Jacqueline Clarke, a lecturer in classics at the University of Adelaide, Australia, “If it was widened to any degree of relation, I suspect that the list would run into thousands.”

Rules, however, are rules, and there are several other considerations to be taken into account before sending off a tweet suggesting a new moon should rejoice in the name Aphrodite McAphrodite-face.

For instance, satellites in retrograde, meaning they rotate in the opposite direction to their orbit, must have names that end in the letter "e". Those turning in the same direction must end with "a".

New names must not be too similar to the already accepted names of other satellites or celestial objects. A list of the names already in use is available here.

Full details and regulations can be found here.

  1. https://www.iau.org/
  2. https://www.minorplanetcenter.net/db_search
  3. https://carnegiescience.edu/NameJupitersMoons
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