If you look up tonight, you’re looking at it. That big, glowing rock in the sky. Most of us just call it "the Moon" and go about our day, but if you’ve ever sat through a late-night astronomy documentary or scrolled through a space enthusiast's Twitter feed, you might have felt a bit confused. Is it Luna? Is it "The Moon" with a capital M? Or does it have some secret, scientific serial number assigned by NASA that we just don't know about? It’s a bit of a weird situation. Honestly, for something that's been hanging over our heads for billions of years, we're surprisingly inconsistent about what is the moon called.
The Name Game: Why "The Moon" is Technically Correct
Let’s get the big one out of the way. The official name for our natural satellite, according to the International Astronomical Union (IAU), is the Moon.
Simple. Boring, maybe. But official.
The IAU is basically the legal authority on what things in space are named. Back in 1919, when they were getting organized, they decided that since we’d been calling it "the Moon" for as long as humans had a language, there wasn't much point in changing it. They do insist on the capitalization, though. When you’re talking about Earth’s natural satellite, it’s the Moon. When you’re talking about those little rocks orbiting Jupiter or Saturn, those are just lowercase "moons."
It’s kind of like how your dog might be named "Dog," but everyone else's pet is just a "dog." We were the first to name one, so we grabbed the generic title and turned it into a proper noun. Pretty bold move by our ancestors, if you think about it.
The "Luna" Confusion
You’ve definitely heard people call it Luna. It sounds fancier. It sounds more "space-age." Many sci-fi writers, from Robert Heinlein to Andy Weir, prefer Luna because it helps distinguish our moon from the hundreds of others in the solar system.
But here’s the thing: Luna is just the Latin word for moon.
In many Romance languages, like Spanish or Italian, they still call it Luna. Scientists often use the adjective lunar—think lunar eclipse, lunar module, or lunar regolith. Because of this, people assume Luna is the "scientific" name. It’s actually not. If you submit a paper to a major peer-reviewed journal and call it Luna, people will know what you mean, but the IAU sticklers will still tell you the name is "the Moon."
Interestingly, the use of "Luna" in English really spiked during the mid-20th century. During the Space Race, there was this collective feeling that we needed a more "planetary" name for our neighbor. Calling it "the Moon" felt a bit like calling Earth "the Dirt."
Why Don't We Give It a "Cooler" Name?
Mars has Phobos and Deimos. Jupiter has Io, Europa, Ganymede, and Callisto. Even tiny Pluto has Charon. So why are we stuck with a generic label?
It’s mostly a historical accident. For thousands of years, we didn't know other moons existed. Until Galileo Galilei pointed his telescope at Jupiter in 1610 and saw four little dots moving around it, we thought we were the only ones with a celestial companion. By the time we realized moons were a common feature of the universe, the name for our Moon was already deeply embedded in every culture on Earth.
Trying to rename it now would be a nightmare. Imagine the paperwork. You'd have to change every textbook, every song lyric ("Fly me to Selene" just doesn't have the same ring to it), and every legal document involving "lunar" rights.
Other Names Throughout History
Before the IAU stepped in to make things official, different cultures had their own identities for the silver orb.
- Selene: The Greek personification of the Moon. She was the sister of Helios (the Sun). This is where we get the term selenology, which is the study of the Moon's geology.
- Mani: In Norse mythology, Mani is the person who drives the chariot of the Moon across the sky, chased by a wolf named Hati.
- Chandra: In Hindu mythology, Chandra is a lunar deity associated with the night and vegetation.
- Chang'e: The Chinese goddess of the Moon. This name is actually very relevant today because China’s lunar exploration program is named the Chang'e project.
The Scientific Designation (If You Want to Get Nerdy)
If you really want to be "that person" at a party, you could argue the Moon has a planetary designation. Since the Earth-Moon system is sometimes considered a "double planet" (because the Moon is so large relative to Earth), some early astronomical catalogs simply referred to it by its relation to us.
However, in modern databases like the JPL Horizons On-Line Ephemeris System, the Moon is often given a numeric code. Its ID is 301.
- 3 = Earth system
- 01 = The first (and only) major satellite
So, next time someone asks what is the moon called, you can tell them it’s "301" if you want to sound like a robot. But maybe don't do that on a first date.
The Case for the "Double Planet"
There is a legitimate scientific debate about whether "Moon" is even a fair categorization. Most moons in our solar system are tiny compared to their host planets. For example, Ganymede is the largest moon in the solar system, but it's much smaller than Jupiter.
Our Moon, however, is about 1/4 the size of Earth.
Because of this massive size ratio, the center of gravity between the two (the barycenter) isn't exactly at the center of the Earth. It’s actually about 1,700 kilometers below the Earth's surface. Some astronomers, like the late Isaac Asimov, argued that we should think of the Earth and Moon as a binary planet system. If we ever officially adopted that view, the pressure to give the Moon a "real" name like Selene or Luna would skyrocket.
Misconceptions About the Name
One of the biggest myths is that NASA renamed the Moon. They didn't. NASA follows IAU conventions. Another weird one is that the "Dark Side of the Moon" is a specific place. It’s not. It’s the Far Side. Both sides of the Moon get equal amounts of sunlight; we just only ever see one side because the Moon is tidally locked to Earth.
It takes exactly the same amount of time for the Moon to rotate on its axis as it does to orbit the Earth. Basically, it’s always facing us. If you were standing on the "Dark Side" during a New Moon, you’d be standing in full, blinding sunshine.
[Image showing tidal locking: Moon rotating once for every orbit around Earth]
How to Talk About the Moon Like an Expert
If you want to sound knowledgeable, the key is using the right word for the right context.
If you are talking about the physical object in the sky: The Moon.
If you are talking about its influence on Earth (tides, gravity): Lunar.
If you are talking about the history of its study: Selenology.
If you are talking to someone from Italy: La Luna.
Honestly, the ambiguity is part of the charm. It’s the only celestial body that is so close and so personal that we don't feel the need to give it a fancy, distant name. It’s just ours.
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Actionable Insights for Moon Watchers
Knowing what the Moon is called is just the start. If you’re interested in our neighbor, here’s how to actually engage with it:
- Check the Phase: Don't just look for "the Moon." Use an app like Stellarium or My Moon Phase to track when it's waxing or waning. The best time to see craters isn't actually during a Full Moon (it’s too bright and flat); it’s during a Quarter Moon when the shadows are long.
- Learn the Seas: Those dark patches aren't water. They’re called Maria (Latin for "seas"). They are actually ancient basaltic plains formed by volcanic eruptions. The most famous is the Mare Tranquillitatis (Sea of Tranquility), where Apollo 11 landed.
- Watch for the Libration: Because the Moon's orbit isn't a perfect circle, it "wobbles" slightly. Over a month, you can actually see about 59% of the Moon's surface, not just 50%. It's a fun challenge for amateur photographers to try and capture those tiny slivers of the "edge" that appear and disappear.
- Use the Right Terminology: Next time you’re out with friends, mention the Terminator. No, not the robot—it’s the line between the light and dark side of the Moon. It’s where the most dramatic scenery is visible through binoculars.
The Moon might have a simple name, but it’s a complex, shifting world. Whether you call it the Moon, Luna, or 301, it remains the only place beyond Earth where humans have actually set foot. That alone makes it worth knowing.
Next Steps for Your Lunar Exploration:
To deepen your understanding of the Moon, start by identifying the three largest "Maria" visible to the naked eye: Mare Imbrium, Mare Serenitatis, and Mare Tranquillitatis. Grab a basic pair of 10x50 binoculars on the next clear night during a First Quarter phase to see the rugged mountains of the Montes Apenninus along the terminator line.