Near side of the Moon

The Moon has a side we always see.

It always faces our Earth. This happens because the Moon turns at the same rate it circles us.

This side looks different from the far side. It has many large, dark spots. These spots are filled with old lava.

They were made by rocks hitting the Moon long ago.

The crust is thinner on this side. This helps make the dark spots. You might even see a face in them!

It is a very special view.

The Moon has a side that always faces Earth. This is called the near side.

The Moon stays turned toward us. This happens because of tidal locking. This means the Moon turns on its axis at the same rate it orbits Earth.

The near side looks different from the far side. It has many large, dark spots. These are called maria, which is the Latin word for "seas."

Long ago, big rocks hit the Moon. These hits made deep basins. Hot lava filled those basins to make the dark spots.

On the near side, maria cover 31.2% of the surface. The far side has very few. This is because the Moon's crust is thinner on the near side.

The crust is the outer layer of the Moon.

Sometimes we see a little more than half of the Moon. This is due to libration. This is a slight wobbling of the Moon. Because of this, we can see up to 59% of the surface over time.

The near side of the Moon is the half that always faces Earth.

Even though Earth turns every day, the Moon keeps the same face toward us. This happens because of tidal locking. This is a way the Moon rotates on its axis. It rotates at the same rate that it orbits the Earth. Because of this, we always see the same side.

The opposite half is called the far side.

Sometimes we can see a little more than just half of the Moon. This is due to a thing called libration. The Moon's orbit is somewhat tilted and shaped like an oval. This causes the Moon to wobble slightly. Because of this wobble, we can see up to 59% of the surface over time.

You might see the Moon look dark during its phases. Even then, it can look faint because of earthshine. This is sunlight that reflects off Earth and onto the Moon.

The near side looks very different from the far side. It has many large, dark splotches called maria. This word is Latin for "seas."

In the 17th century, astronomers like Giovanni Battista Riccioli and Francesco Maria Grimaldi mapped them. They thought these were actual seas of water. We now know there is no liquid on the Moon. These dark areas are actually basins filled with lava. They were made by asteroid impacts about four billion years ago.

There are many real differences in numbers between the two sides. On the near side, maria cover 31.2% of the surface. The far side is much different and has many more craters. Only 1% of the far side is covered by maria.

NASA's GRAIL mission helped us understand why. Research from the Gravity Recovery and Interior Laboratory shows the crust is thinner on the near side. The near side crust and mantle were also hotter than the far side. This heat helped create the larger impact craters we see.

You can see the Moon change depending on where you stand on Earth.

If you live in North America or Europe, the Moon rises in the east. It reaches its highest point in the south. On the equator, the Moon's axis looks horizontal when it rises. If you are in Australia or South Africa, the view is different. The Moon reaches its highest point in the north there. Your location on Earth changes how the Moon looks in your sky.

The near side of the Moon is the hemisphere that always faces Earth.

While the Earth rotates on its axis, the Moon keeps the same surface oriented toward us. This constant orientation is caused by a process called tidal locking. This occurs because the Moon rotates on its axis at the exact same rate that it orbits the Earth. Because of this synchronization, we cannot see the opposite hemisphere, which is known as the far side. Understanding the near side helps us understand how the Moon interacts with our planet.

Even though we usually see only one side, we can actually see slightly more than half of the lunar surface over time. This happens because of a phenomenon called libration. The Moon's orbit is somewhat elliptical, meaning it is shaped like an oval rather than a perfect circle. Its orbit is also inclined to its equatorial plane. These factors cause the Moon to appear to wobble slightly from our perspective. Because of this wobble, humans can view up to 59% of the Moon's surface from Earth.

The appearance of the Moon changes based on the position of the Sun. The Moon is directly illuminated by the Sun, and the changing viewing conditions from Earth create the lunar phases. Even when the near side is dark, it is not completely invisible. It can be faintly seen due to earthshine. Earthshine is indirect sunlight that reflects off the surface of the Earth and onto the Moon.

The near side looks very different from the far side. It is covered in large, dark areas called maria. The word maria is Latin for "seas." In the 17th century, astronomers Giovanni Battista Riccioli and Francesco Maria Grimaldi mapped these areas. They believed these were actual seas of liquid water. We now know that no liquid bodies exist on the Moon. These maria are actually large impact basins filled with lava. They were created by asteroid impacts about four billion years ago.

There is a massive difference in the composition of the two hemispheres. On the near side, maria cover 31.2% of the surface. In contrast, the far side is densely cratered and has very few maria. Only 1% of the far side is covered by these lava-filled basins. NASA's Gravity Recovery and Interior Laboratory, also known as the GRAIL mission, studied this difference. The research shows the Moon's crust is thinner on the near side than on the far side. The near side crust and upper mantle were also hotter than the far side. This heat resulted in the larger impact craters we see today.

How you see the Moon also depends on your location on Earth.

If you are in mid-northern latitudes, like North America or Europe, the Moon rises in the east. It reaches its highest point in the south with its north pole on top. If you are at the equator, the Moon's axis appears horizontal when it rises. In the mid-southern latitudes, such as Australia or South Africa, the Moon reaches its highest point in the north. Even the direction of east and west can seem reversed depending on whether you use astronomical or selenographic coordinates.

The study of the near side connects to many fields of science. Mapping the Moon requires precise coordinate systems to avoid confusion. Astronomers must specify if they are using geographic or astronomical coordinates. This is important because the east-west direction is reversed when the Moon is viewed from Earth. By studying the near side, scientists learn about the history of asteroid impacts and the internal heat of the Moon. These details help us understand the evolution of the entire solar system.