Is The Moon a Star? Uncovering Space Misconceptions

Introduction

Humans landed on the Moon about fifty years ago, so if you still have to ask about its definition, Mr. Armstrong would probably be a bit disappointed.

Simply put, no, the Moon is not a star, nor is it considered a planet. A Moon is a cosmic body made of solid material that does not glow, while stars are made of gas and produce their own light. So essentially, a Moon is a piece of rock floating in space. But why is it not a planet then?

In this blog post, we will learn what a moon is, the main difference between the moons, planets, and stars, and how moons are even born. To lighten the mood, we will also share a few interesting facts about the Moon that we see every day in the night sky.

Moon vs. Star: The Basics

What is a Moon?

The Moon is an astronomical body that orbits the Earth as its only permanent natural satellite, similar to how Earth orbits the Sun. Basically, the Moon is neither a star nor a planet, though it is always by the Earth's side and rotates with us synchronically as a satellite. Contrary to what many think, the Moon doesn't produce its own light. Instead, it reflects sunlight, making it appear bright to us.

While Earth has one Moon, other planets in our solar system have many more or none. Mercury and Venus, for example, are the only two with no moons at all. On the other hand, Jupiter has 79 known moons, while Saturn has a whopping 146 moons!

Each of these moons has unique features and characteristics. Some even have oceans underneath their icy surfaces. For that reason, scientists even speculate that there could be life on some of them. Saturn's largest Moon, Titan, even has lakes and rivers made of liquid methane instead of water.

The Moon in our sky is our Solar System's fifth-largest Moon. Despite that, it is still tiny compared to stars. So, if you decide to adopt a star, keep in mind that even the smallest star you choose is larger than the Moon or anything else beyond your understanding.

What is a Star?

Like our Sun, stars are giant, glowing spheres of gas. They produce light and heat through a process known as nuclear fusion, where different atoms combine and release a lot of energy in the form of light and heat. This energy is what makes stars shine and twinkle for billions of years.

Stars vary in size, temperature, and brightness. Some are thousands of times larger and brighter than our Sun, while others are smaller and don't shine as brightly. Stars are extremely important in the Universe as they act as the main sources of energy. With the help of their gravity, galaxies, planets, and other celestial bodies can form.

No, the Moon is not a star. Although both are celestial bodies glowing in our night sky, their compositions, behaviors, and formation processes are very different.

Stars are larger than planets, Moons, and anything else that floats in space and don't consist of solid materials like the Moon. Hot gases in them produce light and heat, which are not qualities of the Moon. Hence, the Moon isn't a star.

Stars generate their own light through reactions happening in their center. For this very reason, they remain visible even during the day while the Moon disappears from our view.

The Moon primarily consists of rocky material, similar to Earth's crust, and doesn't have the intense heat and pressure needed for these reactions. Instead, it orbits Earth and reflects sunlight, giving it its glowing appearance. This reflective property of the Moon makes it appear brighter or dimmer depending on its position relative to the Sun and Earth.

Is the Moon a Planet?

Someone might still argue that if the Moon isn't a star, you can still define it as a planet. In this case, there are rules set by The International Astronomical Union to determine if something is considered a planet:

• First, it must be in orbit around the Sun.
• Secondly, it must have sufficient mass to take on a near-round shape called the hydrostatic equilibrium.
• Finally, it must have removed any obstacles along its orbital path. In our solar system, planets range from small, rocky worlds like Mercury and Mars to gas giants like Jupiter and Saturn.

Because of these three requirements, we cannot refer to the Moon as a planet since it does not orbit any sun. While the definition of a planet has changed over time (a great example being the discussion about Pluto), these criteria help astronomers classify and study the Universe.

How are Moons Formed?

Knowing how moons form can tell us their unique identity. The most popular theory for our Moon's formation is the Giant Impact Hypothesis, which suggests a Mars-sized body, Theia, crashed into early Earth approximately 4.5 billion years ago. The debris from this impact eventually came together to form the Moon.

In other cases, moons form when a planet's gravity is strong enough to pull in a passing asteroid or object from space, making it a new moon orbiting the planet.

Animation of how the Moon formed following the Giant Impact Hypothesis. Source: Robin Canup/Southwest Research Institute.

While many accept the previously mentioned Giant Impact Hypothesis, it's not the only theory about our Moon's formation. The Fission Theory, for example, suggests that the Moon was once part of the Earth and later broke off because of Earth's high-speed rotation. Other theories propose that Earth's gravity captured the Moon after it formed elsewhere in the solar system. Meanwhile, according to the Condensation Theory, both the Earth and the Moon formed from the same spinning disk of gas and dust that surrounded the early Sun.

For a clearer understanding of the differences between these celestial objects, here are the key distinctions between stars, planets, and moons:

Stars—They emit light because nuclear reactions occur inside them, and their own gravity holds them together.

Planets—Orbit stars, reflecting light but not producing their own. They have shaped into spheres because of their own gravity.

Moons—Natural satellites that orbit planets or minor planets. They don't produce their own light or heat but reflect light from their parent planet's star.

To enhance our understanding of the Universe even further, here are some fascinating facts about our Moon:

It's Drifting Away—The Moon moves about 1.5 inches further from Earth each year because of tidal friction.

We Always See the Same Side—The Moon rotates on its axis at the same rate it orbits Earth, a phenomenon called synchronous rotation. This is why we see only one side of the Moon from Earth.

Moonquakes Exist—Similar to earthquakes on Earth, the Moon experiences what scientists call "moonquakes." There are four different types of moonquakes: deep, shallow, thermal, and meteorite-impact.

The Moon's Name is Moon—Our Moon shares a name with all moons simply because people didn't know other moons existed until Galileo Galilei discovered otherwise. 

There is Water—Missions such as Lunar Prospector, LCROSS, and others have shown that the Moon's surface not only has water but also lots of ice in the shadowy parts of its poles.

As we've explored, the Moon is not a star, nor is it a planet. Each celestial body—moons, planets, and stars—has unique characteristics and behaviors that make them distinct. Here is what we have found out so far:

1. A Moon is the so-called natural satellite that orbits a planet. It is made of solid materials and does not produce heat or light but reflects it from the nearest star.
2. Different planets have different counts of Moons. While Earth has only one, Jupiter, for example, has 79.
3. Stars are giant spheres of hot gasses. They are much larger than any Moon and glow on their own. Because of these differences, we can't consider the Moon a star.
4. The Moon is also not a planet because a planet has to orbit a Sun, have enough mass to be round, and need to have cleared all obstacles from its orbit.
5. There are quite a few theories about how our Moon formed, but the most popular one says that a Mars-sized body collided with Earth, and the debris from this impact eventually created the Moon.

Don't forget to share this article with others who might be asking, "Is the moon a star?" Let's spread the knowledge and encourage a greater appreciation for our amazing Universe. Stay curious, keep asking questions, and keep exploring!

References

1. Lang, Kenneth R. (2011). The Cambridge Guide to the Solar System (2nd ed.). Cambridge University Press.
2. Williams, James G.; Newhall, XX; Dickey, Jean O. (1996). "Lunar moments, tides, orientation, and coordinate frames." Planetary and Space Science. 44 (10).
3. NASA - "The Moon"
4. National Geographic - "Moons" 
5. NASA - "Moon of Our Solar System"