Macquarie Dictionary


The Jupiter discovery: satellite vs. moon



Satellite’s gone way up to Mars
Soon it’ll be filled with parkin’ cars

                         ‘SATELLITE OF LOVE’, LOU REED




We’ve just been told that twelve new moons have been discovered in Jupiter’s orbit, bringing its total to a whopping 79. Armed with this knowledge, we set about updating the definition for Jupiter, a fairly straightforward procedure, you would think. That was well over an hour ago.

As is often the case (almost always, actually), some other part of the definition caught the lexicographical eye and off we went, down the rabbit hole.


noun the largest planet, fifth in order from the sun. Its period of revolution is 11.86 years, its mean distance from the sun 778 321 850 km. Its diameter is 142 985 km, about one tenth that of the sun (11 times that of the earth). It has 79 known satellites, including four large ones discovered by Galileo Galilei, and a faint ring system.
[named after Jupiter1]

The problem was the use of the word satellite, a quite proper and accurate term to use to refer to these heavenly bodies hurtling around Jupiter. However, a few of us thought that moon was somehow more fitting. Why?

It seems likely that, these days, the first thought many people have when they hear satellite in relation to space, is of the artificial satellites used for communications, research, etc., that are in Earth’s orbit. So there is the slightest room for ambiguity when we talk about the satellites of Jupiter. On reflection, the reader would, no doubt, come down on the side of the natural satellite, but the dictionary needs to be as unambiguous as possible in order to convey a meaning efficiently.

So, the definitions for planets are going to be amended to remove the reference to satellites and replace them with moons, and the current fifth definition of satellite is likely to be moved up the ranks to become the second. Changes in language are made up of constant, subtle shifts, and it looks like this is a good and timely example of one.

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