Earth Moon System Facts
The Earth–Moon system is the gravitational relationship between Earth and its only natural satellite, the Moon. Together, they form a tightly connected orbital system that influences tides, stabilizes Earth’s axial tilt, and shapes cycles like lunar phases. The Moon orbits Earth at an average distance of about 384,000 km and is tidally locked, meaning we always see the same side. Understanding the Earth–Moon system helps explain not only how our planet behaves, but also how planetary systems form and evolve across the universe.
/ Star & Planets / Stars & Planets List 0 to 20 Light Years / Sol Star System / Earth System > Earth Moon System Facts
The Moon Location in the Milky Way Galaxy
Local Fluff of Local Bubble
Galactic Orion Arm Spur
26,000 LY from Galactic Center
The Moon is 1.3 Light Seconds Away from the Earth
Desolate Planet Class
Moon
Mercurian Size
0.0123 Earth Mass
2,159 Mile Diameter
3.34 Density
0.166 g
No Atmosphere
250 F to -208 F (Hot to Frozen)
Moon Similarity to Earth
15%
The Moon is Not Similar to Earth
Moon Alien Life Chance
0%
The Moon Has No Chance of Life
Top 10 Most Asked Questions About Earth's Moon (Answered Simply)
What is the Moon made of?
The Moon is made mostly of rock and metal, similar to Earth’s outer layers. Its surface is covered in a dusty layer called regolith, which formed over billions of years from asteroid impacts. Beneath that surface are solid rocks rich in elements like oxygen, silicon, magnesium, iron, calcium, and aluminum.
Inside, the Moon has a small core that is partly molten and mostly composed of iron, along with some sulfur and other elements. Unlike Earth, it has very little atmosphere or water, which is why its surface remains dry, airless, and heavily cratered.
How was the Moon formed?
The most widely accepted explanation is the giant impact theory. It suggests that the Moon formed about 4.5 billion years ago after a Mars sized object collided with the early Earth. The massive impact blasted debris into orbit around Earth, which eventually came together to form the Moon.
Over time, this debris cooled and clumped together due to gravity, becoming a single spherical body. As it formed, the Moon gradually moved into a stable orbit around Earth, shaping the Earth–Moon system we see today.
Why does the Moon change shape (phases)?
The Moon doesn’t actually change shape. What we see as “phases” happens because the Moon orbits Earth, and sunlight always illuminates half of it. As the Moon moves around Earth, we see different portions of the sunlit side from our point of view.
This creates the cycle of phases, new moon, crescent, quarter, gibbous, and full moon. The changing positions of the Sun, Earth, and Moon determine how much of the Moon’s bright side is visible in the night sky.
Why do we always see the same side of the Moon?
We always see the same side of the Moon because it is tidally locked with Earth. This means the Moon rotates on its axis at nearly the same rate that it takes to orbit Earth, about 27 days. As a result, the same hemisphere of the Moon constantly faces us.
This locking effect happened over billions of years due to Earth’s gravity slowing the Moon’s rotation. While we always see the “near side,” the Moon does rotate, and the far side, which is often called the “dark side”, is simply the side we cannot see from Earth.
How far is the Moon from Earth?
The Moon is about 384,400 kilometers, or 238,855 miles away from Earth on average. However, this distance isn’t constant because the Moon’s orbit is slightly elliptical, meaning it moves a bit closer and farther as it travels around Earth.
At its closest point, known as perigee, the Moon can be about 363,000 km away, and at its farthest point, known as apogee, it can be around 405,000 km away. This changing distance is one reason the Moon can sometimes appear slightly larger or smaller in the sky.
Does the Moon affect tides on Earth?
Yes, the Moon has a major effect on tides on Earth. Its gravity pulls on Earth’s oceans, creating a bulge of water on the side facing the Moon. A second bulge forms on the opposite side due to inertia, and as Earth rotates through these bulges, we experience high and low tides.
The Sun also influences tides, but the Moon is the dominant force because it is much closer to Earth. When the Sun, Moon, and Earth align, we get stronger “spring tides,” and when they are at right angles, we get weaker “neap tides.”
Is there water on the Moon?
Yes, there is water on the Moon, but not in the form of lakes or oceans like on Earth. Most of it exists as ice, especially in permanently shadowed craters near the Moon’s poles where sunlight never reaches.
Scientists have also found evidence of tiny amounts of water molecules trapped in lunar soil and rocks. This discovery is important because it could support future human Artemis missions by providing drinking water and even oxygen and fuel resources.
Why is the Moon important to Earth?
The Moon is important to Earth because it helps stabilize our planet’s axial tilt. This stability keeps Earth’s climate relatively consistent over long periods, which is important for seasons and long-term life development.
The Moon also drives Earth’s tides through its gravity, which affects ocean currents and coastal ecosystems. In addition, it has influenced Earth’s evolution, the length of our day, and even early biological rhythms tied to the lunar cycle.
Can Humans live on the Moon?
Humans cannot live on the Moon without advanced life support systems. The Moon has no breathable atmosphere, no liquid water on the surface, and extreme temperatures that range from very hot in sunlight to extremely cold in shadow.
However, scientists are actively studying how people could live there in future Artemis missions using protective habitats, oxygen supplies, and underground or shielded bases. While permanent natural living isn’t possible, short term or supported colonies are considered feasible with current and developing space technology.
What is a Lunar eclipse and how does it happen?
A lunar eclipse happens when Earth moves directly between the Sun and the Moon, blocking sunlight from reaching the Moon. This causes Earth’s shadow to fall on the Moon, making it appear darkened or sometimes reddish in color, which is often called a “blood moon.”
This only occurs during a full moon when all three bodies line up in a straight line. The reddish color happens because Earth’s atmosphere bends and filters sunlight, scattering shorter blue wavelengths and allowing red light to reach the Moon’s surface.
Join the Exo Solaria Union
Help aid in UAP research, Stay informed on the UAP phenomenon, and to help push the United States government for full disclosure regarding UAP and alien species.