Moon

The Moon is in our sky.

It goes around the Earth. This takes about 29 days.

The Moon is very bright at night. It is the brightest thing in the night sky.

It looks like it changes shape. These are called phases.

The Moon has many holes. These holes are called craters. They come from rocks hitting the surface.

Some parts look like dark seas.

Humans have even visited the Moon. Twelve people walked on its surface. They went there in big rockets.

It is a very special place. Do you like to look at the Moon?

The Moon is Earth's only natural satellite. A satellite is an object that orbits a planet.

The Moon stays about 384,399 kilometres away from us. It takes 29.5 days to go around Earth once.

Scientists think the Moon formed a long time ago. They believe a giant object hit the early Earth. This hit sent material into space. This material clumped together to make the Moon.

The Moon's surface is covered in dust. We call this dust regolith. The surface also has many impact craters. These are holes made by space rocks hitting the ground. Some parts look like dark plains. We call these maria, which means "seas."

Gravity pulls the Moon toward Earth. This pull helps make our ocean tides. Because of this, the same side always faces us. Humans have even visited the Moon. Twelve people walked on its surface during Apollo missions.

Now, new plans aim to send people back soon.

The Moon is the only natural satellite that orbits our Earth. It is a huge object in our sky. Its mass is about 1.2% of Earth's mass. The Moon has a diameter of 3,474 km. This is about one-quarter of the size of Earth.

It stays at an average distance of 384,399 km from us. This distance is about 30 times the width of Earth. The Moon is the fifth-largest moon in our Solar System. It is also the largest moon compared to its parent planet.

Gravity is the force that keeps the Moon in orbit. Earth and the Moon are bound by gravitational attraction. This pull is stronger on the sides facing each other. This creates tidal forces that drive Earth's ocean tides. These forces also caused tidal locking. This means the Moon's rotation matches its orbit. Because of this, the same side always faces Earth.

We can see about 59% of the surface from here. This happens because of libration, which are slight changes in angle. This allows us to see parts of the far side.

Scientists have a theory about how the Moon began. They think a giant impact happened 4.51 billion years ago. A body the size of Mars might have hit Earth. This object is often called Theia. The impact blasted material into space around the Earth. This material eventually clumped together to form the Moon.

This theory helps explain why Earth and the Moon are so similar. They have nearly identical chemical compositions. Some models show the Moon came mostly from the impactor. Other models suggest more material came from the early Earth.

ways the Moon looks today tells a story of its past. The surface is covered in a fine dust called regolith. This dust comes from rocks hitting the surface. The Moon's crust is marked by many impact craters. Some craters are young and have bright streaks.

The Moon was volcanically active until 1.2 billion years ago. Lava once filled ancient craters on the surface. These dark, flat plains are called maria, or "seas."

The Moon also has much lower gravity than Earth. It is only about one-sixth of Earth's gravity. This makes it very different from our home.

Humans have always looked to the Moon for knowledge. It has inspired art, science, and even our calendars. The first spacecraft to fly by the Moon was Luna 1 in 1959. Later, the United States sent humans to the Moon. The Apollo 8 crew arrived in orbit in 1968.

Twelve people walked on the lunar surface during the Apollo missions. The last of these landings happened in 1972.

Now, scientists want to return. The Artemis program aims to send humans back in the late 2020s. They want to learn more about the Moon and its water.

The Moon is the only natural satellite that orbits the Earth. It is a planetary-mass object, which means it is large enough to be considered a satellite planet. The Moon plays a vital role in our solar system and our daily lives on Earth. It is the brightest object in our night sky. This brightness comes from its large apparent size, even though its surface reflectance, or albedo, is actually similar to asphalt.

Gravity is the force that holds the Earth and Moon together. This gravitational attraction is stronger on the sides of the two bodies that face each other. This creates tidal forces, which are the main drivers of Earth's ocean tides. These forces also caused a process called tidal locking. This process synchronized the Moon's rotation period, or its lunar day, to its orbital period. Because of tidal locking, the Moon always shows the same near side to Earth.

We can see about 59% of the lunar surface from Earth. This is possible because of libration, which are slight changes in the angles at which the Moon appears to us. This allows us to see parts of the far side. The Moon's diameter is 3,474 km, which is about one-quarter of Earth's diameter. Its mass is only 1.2% of Earth's mass. Within our solar system, it is the fifth-largest and fifth-most massive moon. It is also the largest moon in relation to its parent planet.

Scientists believe the Moon formed about 4.51 billion years ago. The most widely accepted theory is the giant-impact hypothesis. This theory suggests a Mars-sized body named Theia hit the proto-Earth. This oblique impact blasted material into orbit around the Earth. This ejected material eventually accreted, or clumped together, to form the Moon. This impact would have released enough energy to create a magma ocean. This was a vast ocean of liquid rock on both the Earth and the Moon.

The Moon's surface tells a long history of geologic activity. It is covered in regolith, which is a fine dust made of material ejected from the crust by impacts. The surface is covered in impact craters of many different ages. Some young craters have bright ray-like streaks. The Moon was volcanically active until 1.2 billion years ago. During this time, lava filled ancient craters on the near side. These dark, flat plains of basalt are called maria, or "seas."

Humans have a long history of exploring the Moon. The first spaceflights to an extraterrestrial body began in 1959 with the Soviet Union's Luna 1 flyby. In 1966, Luna 9 achieved the first soft landing. Humans first reached lunar orbit with Apollo 8 on December 24, 1968. On July 20, 1969, the Apollo 11 mission landed humans on the surface. By 1972, six Apollo missions had landed twelve humans on the Moon.

Today, robotic exploration is driving a new era of lunar study. Scientists are using robots to confirm if water exists on the Moon. This research is fueling the Artemis program, which aims to return humans to the Moon in the late 2020s. Looking much further ahead, the Moon's future is tied to the Sun. In five billion years, the Moon will be 40% further away from Earth. Eventually, if the Sun becomes a red giant, its atmosphere might cause the Moon's orbit to decay.