What Is The Moon Made Of?

Pictures of the Moon - The Moon from Galileo's Perspective
Pictures of the Moon - The Moon from Galileo's Perspective. NASA

Curious about the Moon? It's a celestial object that appears in our sky each month, often at night or in the early morning, and sometimes even during the day. Humans have wondered about it since the beginning of time. It was only in the mid-1900s that we were able to explore it "in person", and since then with robotic probes that have orbited it, mapped it, and landed on its surface to study its soils.

In the next decade or so, humans will likely return there to live, work, and explore. Let's learn more about this amazing place that lies so close, yet so far from Earth's surface.

What is the Moon Made Of? 

The Moon is Earth's only natural satellite. It formed just after Earth did, possibly from a collision by the infant Earth and a Mars-sized object. It is a rocky body, with a core, overlaid by a mantle and a crust. The Moon may have a solid core surrounded by a soft, partially melted layer. 

The Moon's surface contains oxygen, silicon, magnesium, iron, calcium, aluminum, and traces of chromium, titanium, and manganese. There is evidence of water ice on the Moon, and possibly some underground water. 

The Moon's mass is approximately 7.35e22 kg with a density about 3/5 that of Earth. Its gravitational pull is about 1/6 of Earth's. This means that if you weighed 100 pounds on Earth, you would weigh about 16 pounds on the Moon.


What are the Markings We See on the Moon?

If you look at the surface of the Moon very long, you begin to notice large dark areas, surrounded by lighter areas. The dark regions are called maria, from the Latin word for "seas". Early observers thought these might be watery oceans. There are also many craters scarring the Moon's surface, created when pieces of asteroids and other solar system debris slammed into the surface.

The Moon also has mountains, which are actually parts of large impact craters. A few low-lying "dome"-type features are thought to be the result of volcanic activity on the Moon, which changed the lunar surface throughout history. 

What are the Many Names of the Moon?

The Moon has had numerous names throughout history. Each culture has given it a special name for its place in their rituals and religions. The Moon has been called "Luna" by the Romans, for the goddess of the Moon. It has also been associated with many goddesses and female heroines — among them Artemis (for the Greeks) and Diana (for the Romans). As for the word moon, its roots can betraced through the Middle English mone, from the Old English mona, back to the Latin mensis which means "month". 

What Missions Have Gone to the Moon?

Humans have explored the Moon using landers, mappers, and astronauts since the late 1950s. The first successful one was the Luna 2 "crash" lander, which was sent by the Soviet Union in 1959. The first U.S. probe to successfully make it to the Moon was Ranger 7, which impacted the surface on July 30, 1964 after sending back images and data.  

Both the U.S. and Soviet Union competed on getting to the Moon through the '60s.

Many missions were unsuccessful, but eventually the first humans landed on our nearest satellite on July 20, 1969 during the Apollo 11 mission. The last time humans walked on the Moon was in 1972, during the Apollo 17 mission.

Since Apollo, all lunar exploration has been by robotic probes that orbit or land and take data. In addition to the U.S. missions from Europe, India, Japan, and China have explored the Moon. There are no missions currently in the works for further human missions, but there are many plans "on the drawing boards" that would have people land, live, and work on the Moon. These could occur in the next two decades as plans for Mars mission are expanded. 

Edited and expanded by Carolyn Collins Petersen.