Selenography

People study the Moon's surface.

They look at its big mountains. They also look at deep holes. This work is called selenography.

Long ago, people drew the Moon by eye. Later, they used telescopes to see better.

This helped them make maps.

Then, people used cameras to take pictures. These pictures showed us new things. Some even showed the far side of the Moon.

Now, we send spacecraft to the Moon. They take very clear photos. They can even measure how deep the holes are.

Learning about the Moon is very exciting!

Selenography is the study of the Moon's surface.

Scientists look at its physical features. They map mountains and deep holes called craters. They also study large, dark areas called maria. These maria look like seas from Earth.

Long ago, people drew the Moon by eye. Later, they used telescopes to see better.

In 1840, J.W. Draper used a camera to take the first photo. This changed how we see the Moon. In 1959, a Soviet spacecraft sent the first photos of the far side. This was the first time we saw that part of the Moon.

Today, we use spacecraft to study the Moon.

They use laser tools to measure the ground. We know the Moon is not a smooth ball. The far side is higher than the near side. Its crust, or outer layer, is much thicker there. Some areas near the poles are still hard to see. We are still learning more every day!

Selenography is the study of the Moon's surface and its physical features.

This field is a part of planetary science. People who study this are called selenographists. They work to map and name the different parts of the Moon. They look for mountain ranges and deep holes called craters. They also study large, dark areas known as maria. These maria are important parts of the lunar landscape. Even today, some areas like the poles are hard to see clearly.

Scientists use many tools to understand the Moon's shape. They use a method called laser altimetry to measure heights. They also use stereo image analysis to look at the ground. The Moon is not a smooth sphere. The far side is actually higher than the near side. On average, the far side is 1.9 km higher. The crust, or the outer layer, is also much thicker there. The far-side crust is about 15 km thicker than the near-side crust.

Humans have been looking at the Moon for a very long time. The Greek word for Moon is Selene. Long ago, Democritus said the Moon had mountains and valleys. Around AD 1603, William Gilbert made a drawing with his eyes. Later, the telescope helped people see much better. In 1750, Johann Meyer made the first reliable coordinates. This helped astronomers find specific spots on the Moon. In 1834, Johann Heinrich von Mädler made a large map.

Photography changed how we see the lunar surface. In March 1840, J.W. Draper took the first daguerreotype. This was an early type of photograph. By 1890, lunar photography was its own special field. In 1959, the Soviet Luna 3 spacecraft sent the first photos of the far side. The United States sent many spacecraft like Ranger and Lunar Orbiter. These missions took many pictures from orbit. The Soviet Lunokhods even drove across 50 km of the surface.

Naming the Moon is a very old tradition. In 1647, Johannes Hevelius made a famous lunar atlas. He used names from Earth to name Moon features. Later, a priest named Giambattista Riccioli created a new system. He used Latin names for the Moon's seas and lands. His system was very poetic and used by many people. In 1935, the International Astronomical Union made his system official. They still use many of these names today.

Selenography is the scientific study of the Moon's surface and its physical features.

This field is a subdiscipline of planetary science. It is also sometimes called selenodesy. Historically, selenographists focused on mapping and naming the lunar terrain. They identified features like maria, which are large dark plains, and various crater patterns. They also mapped mountain ranges across the lunar landscape. While much of the Moon is now mapped, some areas remain uncertain. The regions near the lunar poles are still poorly imaged. Some features have uncertain depths that vary by several kilometers. Today, selenography is often grouped under the broader field of selenology, or lunar science.

Scientists use several advanced methods to measure the Moon's topography. Topography refers to the study of the shape and features of a surface. One common method is laser altimetry. This uses lasers to measure the distance to the surface. Another method is stereo image analysis. This uses pairs of images to understand the depth of features.

These tools reveal that the Moon is not a perfect sphere. For example, the far side is higher than the near side. On average, elevations are 1.9 km higher on the far side. This difference is linked to the thickness of the lunar crust. Scientists use gravity and seismic data to study this crust. They believe the far-side crust is about 15 km thicker than the near-side crust.

The Moon's surface contains many distinct types of features. The most visible feature is the South Pole-Aitken basin. This giant basin on the far side has the lowest elevations on the Moon. Near this basin, the elevations are much higher. This area might contain thick ejecta deposits. Ejecta are materials thrown out during an impact event. Other large impact basins also define the landscape. These include the maria Imbrium, Serenitatis, Crisium, Smythii, and Orientale. Each of these basins has regionally low elevations and elevated rims.

Humans have studied the Moon for thousands of years. The word selenography comes from the Greek words Selene and grapho. Selene means Moon, and grapho means to write. The idea that the Moon has mountains is very old. The philosopher Democritus suggested this long ago. However, serious selenography began around the end of the 15th century. In 1603, William Gilbert made the first lunar drawing using only his eyes. When the telescope was invented, drawings became much more accurate. In 1750, Johann Meyer created the first reliable lunar coordinates. This allowed astronomers to locate specific features. In 1779, Johann Schröter began systematic mapping through meticulous measurement.

Photography revolutionized how we see the lunar surface. In March 1840, J.W. Draper produced a daguerreotype of the Moon. A daguerreotype is an early type of photograph. At first, these images were of very poor quality. However, the quality improved rapidly as technology advanced. By 1890, lunar photography was a recognized branch of astronomy. The 20th century brought even more progress through spacecraft. In 1959, the Soviet Luna 3 mission sent the first photos of the far side. The United States launched Ranger and Lunar Orbiter missions to photograph the surface.

Soviet Lunokhods even traveled 50 km to take detailed photos. These missions provided a much clearer view of the Moon.

Naming the Moon, or toponymy, has a long and complex history. In 1647, Johannes Hevelius published the first lunar atlas, called Selenographia.

Hevelius named features after places on Earth. This was different from Michael van Langren, who used Catholic names. Later, Giambattista Riccioli created a very influential naming system. He published his ideas in the Almagestum Novum in 1651. Riccioli divided the Moon into eight numbered octants. He used Latin names for the large maria and seas. Some names described weather, like Mare Nubium, or Sea of Clouds. His system was poetic and easy to expand.

Riccioli's system became the standard for many years. He named craters after famous scholars and philosophers. He even placed certain scientists in Octant VIII. This was a gesture toward the Catholic Church. The International Astronomical Union officially adopted his system in 1935. This official list included 600 lunar toponyms. The IAU later updated the list in the 1960s. New names are now limited to deceased scientists. After the far side was photographed, many features were named after Soviet scientists. Today, selenography continues to connect our understanding of the Moon to the wider field of planetary science.