Astronomy

Why Don't the Sun and Moon Have Names?

All of the planets are named after powerful Greek and Roman gods and goddesses. Their moons are named after mythological characters related to those deities. Stars get cool names like "Sirius" and "Betelgeuse." But our own star and satellite? They get nothing. Our sun and moon are just the sun and the moon. Why is that?

Hello, My Name Is ...

As any parent would know, names have carried tremendous significance throughout the history of our civilization. Your name can reflect important information about your family origin, your gender, and even your personality. Many parents agonize over this decision for months until they land on a name that's just right. And then that's it. No takebacks!

So who gets the all-important power of naming the different parts of our universe? That would be the International Astronomical Union, established in July 1919, 100 years ago. This is the same group that declared in 2006 that Pluto was no longer a planet. The IAU has designated official names for the major planets (Mercury, Venus, Earth, Mars, etc.), minor planets, dwarf planets, stars, comets ... but when it comes to the sun and the moon, the devil is in the details.

When referring to the sun that anchors our solar system and the moon that orbits Earth, the IAU says that the capitalization of the first letter in each word denotes that they're actually proper nouns. (What you might be noticing at this point is that we're leaving them both lowercase. That's because Curiosity uses AP style, which "capitalizes the proper names of planets, including Earth, stars, constellations, etc., but lowercases sun and moon." This is a long-standing feud between science and media, one that likely won't end any time soon.)

What's in a Name?

In the classic John Wayne movie "Big Jake," the Duke's character kept his canine companion's name simple: Dog. Dr. Alexandra Horowitz, author of "Inside of a Dog: What Dogs See, Smell, and Know," writes that such an obvious and half-hearted "name," if it could be called that, doesn't bode well for the pair's future relationship.

"The dog you are about to bring into your home is an individual, with a unique personality, look, and behaviors," she says. "To name him 'dog' is to treat him as utterly unspecial."

So is that the message we're trying to send about the big ball of plasma that literally sustains all life on our planet? How cruel!

But Dr. Britt Scharringhausen, the physics and astronomy department chair at Beloit College, argues it's actually the opposite.

"It may seem odd that these important objects don't have names, but if you think about it, it just reinforces their importance," she writes. "For example, the moon is the moon, not just any moon. It requires no other name, because it's the most important moon!"

NASA contends that the reason is even simpler: Until Galileo Galilei discovered moons orbiting Jupiter in 1610, we didn't even know there were other moons out there. Therefore, our moon was the only moon: the moon. Jupiter's moons (and the other satellites we've discovered since then) were given names like Europa, Callisto, and Ganymede so we could differentiate them from the moon.

In essence, we call the sun "the sun" and the moon "the moon" for the same reason a 30-something still calls their parents "Mom" and "Dad." It doesn't detract from their importance; if anything, it shows just how fundamental a role they play in our lives. They're not just any sun and moon — they're the sun and moon.

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Hear the whole story of how Pluto lost its planet status in "How I Killed Pluto and Why It Had It Coming" by Mike Brown. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Steffie Drucker August 9, 2019

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