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We seem to have named every moon orbiting other planets. Why haven't we named our own moon? And for that matter, why doesn't our sun have a name since we name or number stars?

James K
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Bookaholic
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    I get the confusion for the moon, as there are many celestial objects which are called moons, so "The Moon" may not seem like a name. But there is only one Sun - it's a completely unique identifier for our star. What would suggest that this commonly used, unique identifier is not a name? – Nuclear Hoagie Nov 30 '20 at 16:26
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    Related in Space Exploration SE: Does the moon have a name? As shown in this answer NASA sometimes uses "Luna" as a backup name for Earth's natural satellite. – uhoh Nov 30 '20 at 23:19
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    What is "Earth's star" supposed to mean? That title edit didn't made the question far more confusing. The grammatically correct version by Glorfinel was clearer. I'm rolling back – James K Dec 01 '20 at 23:27
  • @JamesK It's not "ours" but okay. It's not possible that a cogent person would not know what “Do Earth's star and moon have names?” means, though I still struggle to know if it should be “Does”. Planets are generally understood to have stars around which they orbit. It is suspected that there are some exceptions, but those are exceptions (see what I did there?) – uhoh Dec 01 '20 at 23:32
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    This question is prima facie evidence that the ordering of answers needs to be changed. The accepted answer is wrong. – David Hammen Dec 02 '20 at 13:06
  • I'll note that the sun and moon have at least a dozen different names in different human languages, many of them linked with gods. – Hot Licks Dec 02 '20 at 22:47
  • List of adjectivals and demonyms of astronomical bodies – Mazura Dec 03 '20 at 03:19
  • Most people around the world call their tribe or people "People" in their language... a surprising number of mountains have the name "White Mountain" in the respective language, and significant rivers are often called "Big River". Even in the U.S. there's more than one "Big River". – Peter - Reinstate Monica Dec 03 '20 at 06:23
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    This question ignores the reality that for 99.99% of humanity's existence, there was only one sun and only one moon: The Sun and The Moon. – RonJohn Dec 03 '20 at 18:42

8 Answers8

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What is a name?

A name is a word, that is reasonably unique, that is used to identify a person or thing. When a child is born there is no word that identifies it, and so its parents have to choose a "name". Similarly when a new astronomical object, such as an asteroid, is discovered, it has no word that identifies it and so it is assigned first a number and later a name.

But there is already a word that identifies our sun and moon: "the Sun" and "the Moon". There is no need for a new name because they already have a name. Notice that English (unlike some other languages) gives us a typographical clue that these are names, because the first letter is capitalised. The Moon is a moon of the Earth and the Earth is a planet orbiting the Sun.

Earth, Moon and Sun are the correct names in English.

James K
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    We will rule over all this land! And we will call it… this land! (Firefly TV series) – IMil Nov 30 '20 at 23:56
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    "What is a name?" Cue the Vsauce music ;) – Nilay Ghosh Dec 01 '20 at 03:45
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    We'll probably need a new name once we have a bigger colony on Mars, but that's still a while off – Hobbamok Dec 01 '20 at 09:36
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    This is similar to the distinction between "God" and "a god", the former being the sole creator of the Universe as described by monotheistic religions, while the latter is one of many superpowered entities in polytheistic religions. – vsz Dec 01 '20 at 10:35
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    @Hobbamok: Just hope the name for The Earth doesn't become "Old Earth" - that's usually a bad sign. – Peter Cordes Dec 01 '20 at 10:48
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    @PeterCordes The Earth will probably stay "The Earth" while the newly colonized world will be "New Earth" instead ;) – Rafalon Dec 01 '20 at 12:31
  • I think it'll be like Rafalon says, at least if we keep the old traditions up – Hobbamok Dec 01 '20 at 12:57
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    @Hobbamok We do have the Old World and even Old Europe already… – gerrit Dec 01 '20 at 13:07
  • @gerrit but that's different because it's not based on settling somewhere new, but rather different developments in parallel-existing places – Hobbamok Dec 01 '20 at 13:09
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    @Hobbamok New World would seem to be about settling somewhere new, at least from a European perspective. Old/New Europe not so much. – gerrit Dec 01 '20 at 14:10
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    @vsz Also royalty. You might talk about different countries (or, say, chess boards, poker hands, or mattress stores) having kings and queens, but if you're talking about the one in your country, it's always "King" or "Queen". And "earth" can be lower-case when you're talking about just the ground, but capitalized "Earth" when talking about the planet. – Darrel Hoffman Dec 01 '20 at 17:55
  • @Rafalon or perhaps "super earth" ? ("our home"[someone please get this reference]) – Baby_Boy Dec 01 '20 at 19:33
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    @Baby_Boy I made an account just to tell you that yes, I get that reference. Let's go squash some bugs. – STT LCU Dec 02 '20 at 10:52

  • But there is already a word that identifies our sun and moon: "the Sun"< I've counted them twice and am pretty sure that "the Sun" is two words.

     – Pete Kirkham Dec 02 '20 at 15:18
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    I initially took issue with this answer, but it's supported by the IAU's article on the naming of the Moon and on another it links. To the IAU (the official body responsible for naming this stuff), they are indeed "the Sun," "the Moon," and "Earth" (they recommend capitalizing them that way, but leave it up to individual style whether you do). (Note that it's "the Sun" and "the Moon," not just "Sun" and "Moon" as in the last paragraph above.) – T.J. Crowder Dec 02 '20 at 15:32
  • Wikipedia disagrees with this answer. Names Sun, Sol /ˈsɒl/,[1] Helios /ˈhiːliəs/[2] and Alternative names Luna Selene (poetic) Cynthia (poetic) Kinda like Cherilyn Sarkisian and Cher. Turns out when things have a name sometimes they still need other names. – Shane Dec 02 '20 at 19:40
  • @STTLCU you just made my day. – Baby_Boy Dec 03 '20 at 13:46
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Of course the Sun and the Moon have names. The names of those objects in English are "the Sun" and "the Moon". Note the use of a definite article ("the") and the capitalization of the names themselves to indicate a proper name. The Sun and the Moon have many names, at least one name for each for almost every language ever spoken. The translations of those myriad names into English are inevitably "the Sun" and "the Moon". Being the two most obvious celestial objects, those names have been around for a long, long time, almost certainly predating writing.

On the other hand, the knowledge that the Earth is a planet that orbits the Sun is rather new, less than 500 years old. The knowledge that other planets have moons is newer yet, about 400 years old. The knowledge that the Sun is a star is even newer, less than 200 years old. Giordano Bruno was burnt at the stake in 1600 for suggesting that the Sun is a star. It wasn't until the 1830s when scientists were able to measure the enormous distance to even the closest stars.

David Hammen
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    Giordano Bruno's views on the nature of the sun were only a very minor part (and possibly no part at all) in why he was burned. Denying that Christ was divine was the biggest bit. – Valorum Dec 01 '20 at 00:32
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    @Valorum Or even real, as Giordano Bruno was a docetist as well as a pantheist. Pretty heretical. – Cees Timmerman Dec 03 '20 at 03:06
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It is named 'Sol' and the moon was named 'Luna'. Hence the term Lunar explorer and 'Solar' System..

Other cultures have used different names for our Sun and Moon (for thousands of years) - So actually they have multiple names each.

Most people refer to them simply as "The Sun" & "The Moon".

Ryan
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    Isn't "Sol" just Spanish for "sun" and "Luna" Spanish for "moon"? – Bookaholic Dec 01 '20 at 10:13
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    @Bookaholic: The words are originally Latin, and they are sometimes used when you want something distinct from the common words in your own language. – Michael Borgwardt Dec 01 '20 at 10:42
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    @MichaelBorgwardt Not particularly useful for that purpose if your own language is Spanish. – DarthFennec Dec 01 '20 at 17:24
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    @DarthFennec: from a Spanish speaker, there is (almost, I guess?) never confusion. "El sol" is completely different from "un sol" (exactly like "the sun", "a sun" in English). Same with "la luna" or "una luna". They are never used without articles. – Martin Argerami Dec 01 '20 at 18:59
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    The first sentence of this answer is flatly incorrect for english speakers. "Sol" and "Luna" are commonly used in science fiction, but not as official terminology. – Harabeck Dec 01 '20 at 19:20
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    @Harabeck it's always risky to speak for everyone! You'll have to inform NASA that they are not English speakers, and while you're at it, that English is no longer capitalized? – uhoh Dec 01 '20 at 23:27
  • @Bookaholic Our planet is also just called Earth too. We're pretty bad. – DKNguyen Dec 01 '20 at 23:28
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    @MartinArgerami The same applies to English: There is no confusion. "The Sun" is a completely different concept from "a sun", and the same goes with "the Moon" and "a moon". "The Sun" and "the Moon" use a definite article and an initial capital letter on the body. "A sun" and "a moon" use an indefinite article and the body's name is lowercase. – David Hammen Dec 02 '20 at 13:00
  • @Bookaholic Just because the word in a name also has a meaning (and was once derived from that meaning) doesn't mean it's not a name. It can live independently as a name even after the meaning has become irrelevant, e.g. not everyone whose surname is Smith is in fact a smith - though the first people to be called Smith were in fact smiths. First and last names quite regularly use a word that has a dictionary definition (Tanner, Smith, Baker, ...) but that doesn't mean they're not somebody's name or that it must precisely match the dictionary definition. – Flater Dec 02 '20 at 13:11
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    @uhoh I had already seen your example, it doesn't change my statement. Go browse the NASA website (https://www.nasa.gov/moon does not contain the word "Luna"), their press releases, etc. Your example is the first use of "Luna" that I've seen in any even sorta semi-official capacity. Likewise, the IAU explicitly calls it the Moon, and not anything else. So actually, I would say that the use of "Luna" in that example is improper nomenclature. – Harabeck Dec 02 '20 at 15:54
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    @Harabeck While you are informing NASA about their poor English skills, you might want to edit out Sol and Luna on the Sun's and the Moon's wikipedia pages. – Shane Dec 02 '20 at 19:50
  • This should be the top answer. – Vincent Dec 02 '20 at 21:21
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    @Shane I hardly think one use of the informal name in one database is worth raising a stink about with NASA, but sure, snark away. And while you're on those wikipedia articles, maybe you should read their "Name and etymology" sections. Again, astronomers do not seem to use "Sol" or "Luna". The IAU, NASA, any space agency or body of scientific work will refer to them as "the Sun" and "the Moon". (Yes, I saw that the Moon article claims "Luna" is sometimes used in scientific work, but I've never seen it.) – Harabeck Dec 02 '20 at 21:50
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    @Vincent This is a terrible answer. Suppose you want to publish a paper in an English-based scientific journal about the Sun or the Moon and call those bodies "Sol" and "Luna". The journal's editors will quickly fix that (if they accept your paper at all). The official scientific names of those bodies in English are "the Sun" and "the Moon". Period. – David Hammen Dec 03 '20 at 11:07
  • @David Hammen The terms are widely recognized in English any time someone wants to distinguish between our moon/star and other moons/stars. They aren't only terms from Spanish. – Vincent Dec 04 '20 at 03:52
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    @Vincent This would have been an acceptable answer had this question been asked at the Science Fiction & Fantasy StackExchange. But it wasn't asked there. It was asked here, so it is implicitly asking for the names officially used by astronomers. – David Hammen Dec 04 '20 at 09:29
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Well, even though one may encounter some "poetic" names such as Sol or Luna, I believe these bodies are referred to as "the Sun" and "the Moon", and that is the only formal name I've heard of.
As for the reason, I'd say it's because there is no need for special names like Sol because they aren't really used in practice (we've known of the Sun and the Moon for quite a bit), while it is quite important to name newly discovered objects so we would know what to refer to them as.

Tosic
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"The Sun" is fine as long as you're not leaving our solar system; less so "the Moon" when there are hundreds of planetary satellites in this system alone.

In science fiction as varied as Isaac Asimov and ''Star Trek'', the names are Sol and Luna.

EDIT: My point is that sci-fi authors are writing from the point of view of societies with many "suns" and "moons", and those societies have adopted the classical terms as the "current" official names.

Shawn V. Wilson
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  • The latter sentence is a bit weird. Sol is the norse word for Sun (found e.g. in "solar"). https://en.wikipedia.org/wiki/S%C3%B3l_(sun). Luna is the latin word for the moon (as witnessed by "lunar"). (Both being the names of their respective gods who were responsible for those phenomena, but that's beside the point.) Has nothing to do with SciFi or those authors... – AnoE Dec 02 '20 at 11:16
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    @anoe Sol is also Latin for Sun. – Toivo Säwén Dec 02 '20 at 12:52
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    This should not be the accepted answer. – David Hammen Dec 02 '20 at 13:00
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    "The Moon" is also fine if you don't leave Earth, which is a valid assumption for the vast majority of people using the term. – chepner Dec 02 '20 at 19:16
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    Strictly speaking, "sól" is the Old Norse word, and "sol" is the Latin word. The two are cognates, both coming from the same Indo-European root that also means "sun". – chepner Dec 02 '20 at 19:19
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    @DavidHammen It's a little strange, isn't it, since older answers seem to cover it pretty well... – ReinstateMonica3167040 Dec 02 '20 at 20:57
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    @DavidHammen I'm a little surprised myself. – Shawn V. Wilson Dec 03 '20 at 04:55
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    @DavidHammen it's a fine answer because of the edit: sci-fi authors are writing from the point of view of societies with many "suns" and "moons", and those societies have adopted the classical terms as the "current" official names. The other answers are also right: the names are The Sun and The Moon. – RonJohn Dec 03 '20 at 18:40
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I did not find any definite reference, but if the Sun and the Moon had any other official name, it would have come from the International Astronomical Union (IAU). The only reference I found was a mention in passing of Sun and Moon (capitalized). https://www.iau.org/public/themes/naming/ There may be more information hiding in some publications. But if they had another official name for these two celestial bodies, it would seem reasonable to expect that it would be featured fairly prominently on their Web site.

It would in fact make some sense to have distinctive names, to avoid statements like "Alpha Centauri is the sun of another planetary system" where sun does not refer to our Sun. That may have been the idea behind the notion that there is a distinction between "Sun" and "Sol". But it does not look like the IAU backs this up.

As best as I can tell, that idea may have originated in Hollywood, specifically Star Trek. Since I do not have any definite information to back that up, take that with a grain of salt.

Kevin Keane
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  • Sol and Luna are Latin. Like plants, animals, and planets, it makes sense to use a dead language with simple characters as a global scientific standard in place of many localized names. – Cees Timmerman Dec 03 '20 at 02:57
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Because there's no need to. "Sun" and "Moon" are relative terms and it's clear which bodies we mean (as long as we say the Sun / the Moon) when on Earth. If you stood on Proxima b's surface, Proxima Centauri would be your Sun, Proxima b's spherical satellite (if it has one) would be your Moon, and the Earth's Sun would be an average star in the night sky we'd have to find a name for in such case (e.g. Cassiopeia VI since it would enlarge the constellation of Cassiopeia by another star). But as long as you're on Earth, it doesn't matter.

You can even use the term "Earth" relative for another planet you're on in the sense of "land", just like we talk about a "geology of Mars" (geos is Greek for 'Earth').

Greenhorn
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    Presumably if we start living on other planets and travelling between their moons becomes more commonplace, calling our moon 'The Moon' might actually start to be problematic. Especially when discussing things in the frame of reference outside of any particular planetary system. – JeffUK Dec 01 '20 at 11:23
  • @JeffUK It's just in case a planet has exactly one spherical satellite. If the planet's inhabitants aren't capable of interplanetary spaceflight, they would call it simply 'the Moon'. – Greenhorn Dec 01 '20 at 11:25
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There isn't a general naming scheme. However, we can leverage a pattern for naming the apsis of orbits. We historically named these on a per-host body basis, so apogee and perigee were the names for the furthest and closest an orbit gets to the Earth, respectively. The -gee suffix is derived from Gaia, so that would be the name for our planet. The solar apsis are apohelion and perihelion, the -helion suffix being derived from "Helios," the Greek god of the sun. Lunar apsis have used -lune, -cynthion and -selene, deriving from names Luna, Cynthia, and Selene.

These are, of course, just one of many names that could be used, but the pattern of using historical gods would have value in such a situation. We might talk of a "new Earth" or a "new Sun" to describe a planet or a star that is similar in characteristics to our planet or star, so those names might shift from nouns to adjectives, describing planets or stars. However, there is little reason for a historical deity to be associated with a celestial body that was never seen by that historical society. It is unlikely names like Luna or Helios would ever be applied to bodies outside our solar system. Whether they would get applied to bodies in our solar system is a question for the linguists. It would depend highly on how we adapt other words like "sun" and "sol" in a multi-solar-system society.

And that linguistic adaptive approach would answer your question as to why we don't have names for them. Currently "sun" is sufficiently descriptive that it acts like a noun in our speech and needs no additional context. "The moon," with the pronoun "the" included is sufficiently descriptive. For the ancient Greeks, there wasn't even a need to identify the Earth's moon from a moon of Jupiter, because they didn't know Jupiter had moons.

For all I know, we'll name "the Sun" "Sun_00001" to disambiguate. But there does seem to be a history of leveraging the ancient deities when disambiguation is needed in a language.

Cort Ammon
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