Meteorites are the reason for the formation of craters on the moon. Craters on the Moon

But first, a photograph of the Moon with the announcement and location of those objects that will be discussed in this article:

Probably the most famous crater on the moon, many do not know its name, but they definitely see it on the moon. It can be "guessed" even with the naked eye on a full moon, because on a full moon it is the brightest spot on the moon due to the rays emanating from the crater up to 1500 km in length

The crater was formed on the moon about 100 million years ago, with an average diameter of 85 km and a maximum depth of almost 5 km. By lunar standards, the crater is considered young. In the approximation of 5000 mm, the stepped structure of the inner shaft on the walls of the crater is clearly drawn. And also the central hill of the crater is divided into separate rocks, which reaches a height of about 2 km.

I think that the second most recognizable is the Copernicus crater. It is clearly visible, both in the full moon and in other phases of the moon, when illuminated by the light of the sun. Its good visibility is due to the fact that the crater is located in the middle of the Storm Ocean, in dark volcanic rock, and those emissions that appeared as a result of the collision have a lighter color, due to which it contrasts on the surface of the Moon.

In my opinion, a very interesting crater. At different phases of the moon, it looks completely different, due to the play of light and shadows. This time it was almost completely lit, and it seems a little flat, but the shadows do not hide all of its internal terrace-like structure. The age is estimated at 800 million years, almost 4 km deep and about 96 km in diameter. Around Copernicus, you can observe a huge network of secondary small craters formed by fragments of rocks as a result of an explosion during the fall of the meteorite that created Copernicus. An interesting detail is that the Apollo 12 astronauts took soil samples from the ray structure of this crater.

In its visible nature, it is very similar to Copernicus, and they are located in the neighborhood.

The crater is relatively small, about 30 km in diameter and 2.5 km deep. But due to the dark basalt plateau of the Ocean of Storms and the Sea of Islands, it stands out strongly on the surface of the Moon with its bright ray system.

4) Clavius Crater
The most beautiful crater on the moon. Beautiful precisely because of its structure of secondary craters, easily recognizable, reminds me of a funny cartoon face.

It is located at the south pole of the moon, under Tycho crater. It is a very ancient crater with an age of about 4 billion years, a diameter of 230 km and an average depth of about 2 km, and a maximum of about 5. The two craters that hit the Moon later and broke the walls of Clavius are called Porter (upper) and Rutherford (lower). They have almost the same size at 50 km in diameter.
An interesting feature of Clavius is its bottom. It is quite flat except for the fall of younger meteorites. A little to the left of the center of the crater is the "central hill", which for some reason is offset from the center. It is assumed that the bottom of the crater was formed much later than its formation.

A crater with a very interesting bottom, with numerous furrows and faults

Located on the northern edge of the Sea of Humidity. Ancient destroyed crater with a diameter of 110 km. and relatively shallow depth: 1.5 km. Against this background, the central hill looks higher than the walls of the crater, although in fact its height is slightly less than 1400 meters. The structured crater floor owes its appearance to the formation of the Humidity Sea. During this period, the crater underwent lava corrosion.

A small round lunar sea with a diameter of 420 km.

The age is estimated at about 4 billion years. It is flooded with trapped lava, the depth of which reaches 3 km. Interesting craters on the south side of the sea are the Vitello crater (pictured a little lower and to the right of the center), the central part of which resembles a podium on which the peak of the crater is located. And the almost completely destroyed Doppelmaeyr crater, with a central peak with even triangular sides.

Ancient crater, located slightly to the left and above the Clavius crater

The diameter is almost 150 km, the depth is 4.5 km. By nature, it resembles Clavius. The central slide is also shifted to the left of the center. Presumably, the bottom of the crater was formed in the same way after the formation of the crater itself.

Unusual lunar formation. Many hypotheses about the artificial origin of this wall went on the Internet.

In fact, this is a tectonic fault on the moon. The length of the wall reaches 120 km. Presumably the height of the wall is from 200 to 400 meters. It is best to observe the wall on the 8th or 22nd day of the moon's rise.
Other objects in the picture: to the left of the wall you can see a crack in the form of a worm, about 50 km long, with rounded ends. The crack was formed, most likely, from lava flows. And the largest craters: Arzakhel above, below the double crater Febit and the ancient crater at the bottom of the photo - Purbakh.

9) Furrows of Hyginus and Ariadeus
Formations of mysterious origin - long furrows on the surface of the moon, as well as chains of lunar craters. It is especially puzzling when chains of lunar craters line up exactly with the furrow, as seen in this photo.

The Ariadeus furrow (right band in the image) reaches a length of 250 km. It is one of the most famous furrows on the visible part of the lunar surface. The origin of the furrow is not known. Presumably - the result of lava flows.
Hygin's furrow, located on the left side of the photo. No less long furrow - 203 km in length. It is interesting in that the chain of craters exactly coincided with the direction of the furrow itself. According to the theory of probability, such an event is negligible, or rather impossible. Not only are chains of craters a rare and mysterious phenomenon (may be formed from the tail of comets), so for this chain to hit a furrow and turn in a direction exactly like a furrow, this is really not explained at the moment.

Romantic harbor on the moon. It's a pity, instead of the sea, dried and hardened lava.

Initially, it was a huge impact crater with a diameter of 250 km. Now the southeastern part of the bay is connected to the sea of rains. The edges of the rainbow bay form Cape Laplace in the north, 2.5 km high, and Cape Heraclid in the south, 1.3 km high. And the ramparts of the former crater are called the Jura Mountains or the Jura Mountains. The height of these mountains reaches three kilometers. The formation of the bay is commensurate with the formation of the sea of rains, this is approximately 3.5-4 billion years ago. However, near the shores of the bay there is an older magma that differs in color from the main solidified magma of the Sea of \u200b\u200bRains, which may indicate an earlier origin of Rainbow Bay. The bay is located on the northern hemisphere of the moon and is visible even to the naked eye. The bay was visited by the Soviet Lunokhod 1 in 1970 and the Chinese lunar rover Chanye 3 in 2013.

11) Plato Crater and Alpine Valley
Photo of another interesting part of the surface of the Moon (the original is 1214 pixels wide by clicking on it)

This site is interesting both with the Plato crater and with the mountain network of the lunar Alps.
Almost 4 billion years old Plato crater, 100 km in diameter and 2 km deep, has a very flat bottom filled with magma. There was not even a trace of the central hill of the crater, and its walls collapsed due to lava exposure. Surprisingly, large meteorites did not fall to the bottom of the crater in later periods. At 5000 mm, only a few small craters can be distinguished in its area. From the northern side of the crater one can see the "furrow of Plato", resembling a meandering riverbed. Presumably, the meteorite that formed the crater fell into the mountain range, thereby completely destroying them.
The Alps and the Alpine Valley, which are located to the right of Plato, form lunar mountains, separating them with a huge canyon. This canyon is the Alpine Valley.
As suggested, the Alps were formed as a result of the fall of an asteroid. The highest mountain of the lunar Alps was named Mont Blanc, by analogy with the terrestrial Alps. On the moon, Mont Blanc is more than three kilometers high. And the entire mountain network is about 260 km long with an average mountain height of 2.5 km. But the main attraction of the Alps, of course, is the Alpine Valley. This valley extends for 160 km with an average width of 10 km. Scientists explain the formation of the valley as a graben formed as a result of the subsidence of the lunar crust along the fault that appeared during the formation of the Sea of Rains basin, and subsequently the depression was filled with lava. At the bottom of the valley there is a narrow furrow no more than 1 km wide (only the central part of this furrow was recorded in the photo), it stretches for almost 140 km.

12) North Pole of the Moon
The north pole of the moon is completely covered with craters of various diameters.

But what's interesting about the north pole? And the fact that NASA experts discovered frozen water, that is, ice, in 40 craters of the north pole of the moon. There are no samples yet, and evidence for the existence of ice is based on analyzes by the LRO orbital station and the Russian LEND instrument, as well as the LCROSS and Chandrayaan-1 stations.
Recognizable craters at the north pole are Anaxagora and Goldschmidt. The latter is an ancient ruined crater 115 km in size and 3.5 km deep. Anaxagoras is a relatively young crater, 1 billion years old, 50 km in size and three kilometers deep. In the photograph, they are lower and to the left of the center, recognizable by the fact that the meteorite that formed Anaxagoras fell on the western wall of Goldschmidt.

13) Crater Herschel J. and Harpal
Two well-marked craters near the north pole. They are located above the rainbow bay.

The crater Herschel J. (pictured on the right side) almost collapsed and disappeared. Its walls are no longer as clear as those of young craters. Today, the crater is only 900 meters deep and 155 km in diameter.
The Garpal crater (pictured left) is a young impact crater. 40 km in diameter, 3.5 km deep. and the central slide is only 350 meters.

14) Craters Archimedes, Autolycus and Aristillus
Three known lunar craters.

The lowest crater in the photo is Archimedes. Age 3.5 billion years, diameter 81 km and depth 1.5 km. Located in the Sea of Rains. Like the Plato crater, its bottom is filled with lava and is therefore fairly flat with a few small craters. Archimedes has a system of furrows, the photograph shows how barely noticeable lines going north for more than 150 km.
The middle crater is Autolycus. 40 km in diameter and 3.5 km deep. Age estimated at 1 to 2 billion years
The upper crater is Aristillus. About the same age as Autolycus, a little wider, about 55 km in diameter, and a little less depth - 3.3 km.
An interesting detail of the image is the system of furrows in the lower right part. These are the Hadley furrows, bordering the Apennine mountain ranges. The furrow is 116 km long and about 1.2 km wide. with a depth of 300 meters. It is assumed that the furrow was formed as a result of underground lava flows with subsequent collapse of the ceiling.

That's all. In conclusion, I want to show how these objects are located on the full moon for greater recognition:

Click for larger size available. Full moon photo taken in 2011

I really hope that now it will be even more interesting for you to look at the Moon, especially on warm evenings and nights. And maybe you can share with someone what you learned today :)

A little about the technical side of filming. All photographs were taken with a Celestron SCT 8" reflex lens with an aperture of 203 mm and f / 10 aperture. The focal length of 5000 mm was achieved using a Televue Powermate 2.5x teletender. Videos were recorded on a VAC-136 black and white camera in the infrared spectrum with an Astronomic IR filter -pass 742.
Processing was carried out in the programs:
1) frame stacking - AutoStakkert 2. Registax 6
2) sharpening (deconvolution and wavelets) - AstroImage 3 Pro
3) final histogram color correction - Photoshop CS
PS: why not single frames and not a "reflex camera" can be read

Lunar craters, from the very discovery by Galileo, never cease to amaze scientists and amateur astronomers. are still being studied. They give an idea of what chaos was at the beginning of the existence of the solar system.

Lunar craters - the same age as the solar system. Most of them arose at the stage of the formation of the solar system. Then there were many fragments and parts of unformed planets in it. Falling on the moon, they formed potholes.
The largest system of craters is located on the far side of the moon. Hertzsprung, whose diameter is 591 km, cannot be seen from Earth, because it is located on the far side of our satellite. This is a percussion formation.
Rays of Tycho are the trace of a terrible collision. In the lower part of the disk of the Moon visible from the Earth, a bright crater is visible, from which light stripes diverge to the sides, which are visible from the earth even with binoculars. Light stripes are nothing but traces of a catastrophe that occurred many millions of years ago. From the monstrous impact, the rock scattered and settled over distances of thousands of kilometers.
This formation is older than Tycho, and also has rays, but not as noticeable. They are best seen on a full moon. The walls of Copernicus rise 2.2 km above the surface, and its diameter is 60 km.
Aristarchus - one of the most mysterious craters of the moon. This formation has a complex structure. Scientists also recorded the flow of alpha particles emanating from it and suggested the presence of deposits of radioactive materials there.
A lone mountain, similar in shape to a pyramid, rises 1600 m above the plain. It is part of a chain of mountains located around a huge crater. In ancient times, it was filled with lava, which formed the so-called Sea of Rains.
In the year 53 of the last century, an amateur astronomer photographed a flash on the lunar surface. It was a photograph of the collision of the Earth's satellite with a large space object. After some time, when spacecraft were sent to the Moon, which took high-quality pictures of the surface, a crater was discovered at the site of the outbreak.
A new crater, for the first time in hundreds of years of observations, was discovered on the side of the moon facing the Earth. It was named after the brave female pilot who crossed the Atlantic, Emilia Earhart.
With proper lighting, the network of faults in the surface of this natural formation creates a fairly regular pattern. You can see such a miracle at the edge of the visible disk of the planet. The pattern arose as a result of gradual flooding with lava and uneven cooling of the rock.
By studying some impact craters, scientists got a chance to look under the Moon's dense mantle.. Colliding at great speeds with our satellite, some asteroids damaged its upper layer. Based on spectrograms, one can understand the composition of the internal "stuffing" of the Moon.
The crater discovered by astronomers on the far side of the Moon has a strange shape, which indicates a tangential impact of a cosmic body. Scientists have suggested that this is a trace of the fall of the American Lunar Orbiter 2 on the planet. This device fell in October 67.
Large impact craters have also been discovered on our planet.. Despite the widespread belief that the earth's atmosphere is a kind of planetary shield that protects against asteroids, this is not entirely true. On the Moon, this is a trace of the impact of large objects, with a diameter of tens of kilometers. Our atmosphere cannot protect the planet from such a bombardment. The proof of this is the presence on the surface of the Earth of large craters discovered relatively recently.
Until recently, it was believed that geological activity ended on the Moon a very long time ago, but studies of some craters show that they are completely new, by space standards. Thus, activity continues under the surface of the Earth's satellite.
Almost in the center of the visible disk of the moon is Alphonse, the bottom of which sometimes becomes poorly distinguishable even with good optics. At its bottom accumulates gas ejected from the bowels of our satellite.
Most lunar craters are named after scientists and explorers.. With the beginning of the era of astronautics, they began to be given the names of famous astronauts.

For many millennia, people have been watching the amazing celestial body, called the Earth's satellite - the Moon. The first astronomers noticed dark areas of various sizes on its surface, considering them to be seas and oceans. What are these spots, really?

Characteristics of the Moon as a satellite of the Earth

The Moon is the closest to the Sun and the only satellite of our planet, as well as the second clearly visible celestial body in the sky. This is the only object of astronomy that has been visited by man.

There are several hypotheses for the origin of the moon:

The destruction of the planet Phaethon, which collided with a comet while orbiting the asteroid belt between Mars and Jupiter. Part of its fragments rushed to the Sun, and one to the Earth, forming a system with a satellite.
During the destruction of Phaeton, the remaining core changed its orbit, "turning" into Venus, and the Moon is a former satellite of Phaeton, which the Earth captured into its orbit.
The moon is the preserved core of Phaethon after its destruction.

With the first telescopic observations, scientists were able to view the moon much closer. At first, they perceived the spots on its surface as water spaces similar to those on the earth. Also, through a telescope on the surface of the Earth's satellite, you can see mountain ranges and bowl-shaped depressions.

But over time, when they learned about the temperature on the Moon, reaching +120°C during the day and -160°C at night, and about the absence of an atmosphere, they realized that there could be no talk of water on the Moon. By tradition, the name "Lunar seas and oceans" has remained.

A more detailed study of the Moon began with the first landing of the Soviet Luna-2 apparatus on its surface in 1959. The subsequent Luna-3 apparatus for the first time made it possible to capture its reverse side, which remains invisible from the Earth, in the pictures. In 1966, with the help of the lunar rover, the structure of the soil was established.

On July 21, 1969, a significant event took place in the world of astronautics - the landing of a man on the moon. These heroes were the Americans Neil Armstrong and Edwin Aldrin. Although in recent years many skeptics have been talking about the falsification of this event.

The Moon is located at a great distance from the Earth by human standards - 384,467 km, which is approximately 30 diameters of the globe. In relation to our planet, the Moon has a diameter slightly larger than a quarter of the Earth, makes a complete revolution around it in an elliptical orbit in 27.32166 days.

The moon is made up of a crust, mantle and core. Its surface is covered with a mixture of dust and rocky debris formed from constant collisions with meteorites. The atmosphere of the Moon is very rarefied, which leads to a sharp fluctuation in temperatures on its surface - from -160°C to +120°C. At the same time, at a depth of 1 meter, the temperature of the rock is constant and amounts to -35°C. Due to the rarefied atmosphere, the sky on the Moon is constantly black, and not blue, as on Earth in clear weather.

Moon surface map

Observing the Moon from the Earth, even with the naked eye, one can see on it light and dark spots of various shapes and sizes. The surface is literally dotted with craters of various diameters, from a meter to hundreds of kilometers.

In the 17th century, scientists decided that the dark spots were the lunar seas and oceans, believing that there was water on the Moon, just like on Earth. Light areas were considered land. The map of the Moon's seas and craters was first drawn by the Italian scientist Giovanni Riccioli in 1651. The astronomer even gave them his own names, which are still used today. We will learn about them a little later. After the discovery by Galileo of the mountains on the moon, they began to be given names in the likeness of the Earth.

Craters are special ring mountains called cirques, they also got their names in honor of the great scientists of antiquity. After the discovery and photography by Soviet astronomers using spacecraft of the far side of the Moon, craters with the names of Russian scientists and researchers appeared on the map.

All this is detailed on the lunar map of both its hemispheres, used in astronomy, because a person does not lose hope not only to land on the moon again, but also to build bases, establish a search for minerals and create a colony for a full-fledged life.

Mountain systems and craters on the moon

Craters on the Moon are the most common landform. These multiple traces of the work of meteorites and asteroids over millions of years can be seen on a clear night on a full moon without the help of optical instruments. Upon closer examination, these works of space art amaze with their originality and grandeur.

History and origin of "moon scars"

Back in 1609, the great scientist Galileo Galilei designed the world's first telescope and had the opportunity to observe the moon in multiple magnification. It was he who noticed all kinds of funnels on its surface, surrounded by "ring" mountains. He called them craters. Now let's find out why there are craters on the Moon and how they formed.

They were all basically formed after the formation of the solar system, when it was bombarded by celestial bodies left after the destruction of the planets, which rushed through it in huge numbers at crazy speed. Almost 4 billion years ago, this era ended. The earth got rid of these effects due to atmospheric influences, but the moon, devoid of an atmosphere, did not.

Astronomers' opinions about the origins of craters have been constantly changing over the centuries. They considered such theories as volcanic origin and the hypothesis about the formation of craters on the Moon with the help of "space ice". A more detailed study of the lunar surface, which became available in the 20th century, nevertheless, in its overwhelming majority, proves the impact theory from the impact of a collision with meteorites.

Description of lunar craters

Galileo in his reports and writings compared lunar craters with eyes on the tails of peacocks.

The ring-shaped appearance is the most important feature of the lunar mountains. You won't find them on Earth. Outwardly, the lunar crater is a depression, around which high round shafts rise, with which the entire surface of the Moon is dotted.

Lunar craters bear some resemblance to terrestrial volcanic craters. Unlike the earthly ones, the peaks of the lunar mountains are not so sharp, they are more round in shape with an oblong shape. If you look at the crater from the sunny side, you can see that the shadow from the mountains inside the crater is greater than the shadow outside. From this we can conclude that the bottom of the crater is lower than the surface of the satellite.

The sizes of craters on the Moon can vary in diameter and depth. The diameter can be both scanty up to several meters, and huge, reaching more than one hundred kilometers.

The larger the crater, the correspondingly deeper. The depth can reach 100 m. The outer shaft of large "lunar bowls" for more than 100 km rises up to 5 km above the surface.

Of the relief features that distinguish lunar craters, the following can be distinguished:

Inner slope;
External slope;
The depth of the crater bowl itself;
System and length of rays diverging from the outer shaft;
The central peak at the bottom of the crater, which is found in large ones, is more than 25 km in diameter.

In 1978, Charles Wood developed a peculiar classification of craters on the visible side of the Moon, which differ from each other in size and appearance:

Al-Battani C - a spherical crater with a sharp shaft, up to 10 km in diameter;
Bio - the same Al-Battani C, but with a flat bottom, from 10 to 15 km;
Sozigen - an impact crater ranging in size from 15 to 25 km;
Trisnecker is a lunar crater up to 50 km in diameter, with a sharp peak in the center;
Tycho - craters with a terraced slope and a flat bottom, over 50 km.

The largest craters on the moon

The history of the study of lunar craters can be read by the names given by their explorers. As soon as Galileo discovered them with a telescope, many scientists who tried to create a map came up with their own names for them. The lunar mountains of the Caucasus, Vesuvius, the Apennines appeared ...

Names were given to craters in honor of the scientists Plato, Ptolemy, Galileo, in honor of St. Catherine. After the promulgation of the map of the reverse side by Soviet scientists, the crater named after. Tsiolkovsky, Gagarin, Korolev and others.

The largest officially listed crater is Hertzsprung. Its diameter is 591 km. It is invisible to us, as it is located on the invisible side of the moon. It is a huge crater in which smaller ones are located. Such a structure is called a multi-ring structure.

The second largest crater bears the name Grimaldi, named after the Italian physicist. Its diameter is 237 km. Crimea can be freely located inside it.

The third huge lunar crater is Ptolemy. Its width in diameter is about 180 km.

Oceans and seas on the moon

The lunar seas are also a bizarre shape of the relief of the satellite's surface in the form of huge dark spots, attracting the eyes of more than one generation of astronomers.

The concept of the sea and ocean on the moon

For the first time the seas appeared on the maps of the Moon after the invention of the telescope. Galileo Galilei, who first examined these dark spots, suggested that these were water spaces.

Since then, they began to be called seas and appeared on the maps after a detailed study of the surface of the visible part of the Moon. Even after it turned out that there is no atmosphere on the Earth’s satellite and there is no possibility of the presence of moisture, they did not fundamentally change it.

The seas on the Moon - strange dark valleys on its visible part from the Earth, are huge low-lying areas with a flat bottom, filled with magma. Billions of years ago, volcanic processes left an indelible mark on the relief of the lunar surface. Huge areas extend over distances from 200 to 1000 km across.

The seas appear dark to us because they do not reflect sunlight well. The depth from the surface of the satellite can reach 3 km, which boasts the size of the Sea of \u200b\u200bRains on the Moon.

The largest sea is called the Ocean of Storms. This lowland stretches for 2000 km.

The visible seas on the Moon are located within the ring-shaped mountain ranges, which also have their own names. The Sea of Clarity is located near the Serpent's Ridge. Its diameter is 700 km, but it is not remarkable for this. Of interest are the various colors of lava that stretch along its bottom. A large positive gravity anomaly has been detected in the Sea of Clarity.

The most famous seas, bays and lakes

Of the seas, one can distinguish such as the sea of Humidity, Abundance, Rains, Waves, Clouds, Islands, Crisis, Foam, Known. On the other side of the Moon there is the Sea of Moscow.

In addition to the only Ocean of Storms and seas, there are bays, lakes and even swamps on the Moon, which have their own official names. Let's consider the most interesting ones.

The lakes received such names as the lake of Awe, Spring, Oblivion, Tenderness, Perseverance, Hatred. Bays include Loyalty, Love, Tenderness and Good Luck. The swamps have corresponding names - Rotting, Sleep and Epidemics.

There are some facts related to the seas on the surface of the Earth's satellite:

The Sea of Tranquility on the Moon is known for being the first place where a human foot set foot. In 1969, American astronauts carried out the first landing on the moon in the history of mankind.
Raduga Bay is famous for the exploration of the Lunokhod-1 planetary rover in 1970 near it.
At the Sea of Clarity, the Soviet Lunokhod-2 conducted its surface research.
In the Sea of Plenty, the probe "Luna-16" in 1970 took lunar soil for testing and delivered it to Earth.
The Known Sea became famous for the fact that in 1964 the American Ranger-7 probe landed here, which for the first time in history took a close-up photo of the Moon's surface.

What is the moon sea - look at the video:

The seas and craters of the Moon, thanks to modern research and images, are mapped in great detail on the map of the lunar surface. Despite this, the Earth's satellite keeps a lot of secrets and mysteries that have yet to be unraveled by man. The whole world is looking forward to sending the first colony, which will lift the veil of this amazing place in our solar system a little more.

lunar crater

lunar crater called a bowl-shaped recess in the surface of the moonhaving a relatively flat bottom and surrounded by an annular raised shaft. In accordance with modern concepts, the vast majority of lunar craters are impact craters. A small part of the lunar craters are still considered volcanic calderas.

History and origin of craters

Type	typical representative	Morphological features	Crater diameter
ALC	Al-Battani C	A spherical crater with a sharp ridge, a smooth inner slope and a spherical bottom of the crater bowl	up to 10 km
bio	Bio	Same as type ALC but with a flat bottom in the central part of the crater bowl	10 - 15 km
SOS	Sosigen	Flat-bottom bowl crater, inner slope terraces and central peak absent	15 - 25 km
TRI	Trisnecker	The presence of a central peak (starting from a diameter of 26 km), the inner slope loses its smoothness and has traces of collapse	15 - 50 km
TYC	Quiet	Terraced inner slope, relatively flat bowl bottom, often have a developed central peak	over 50 km

Craters larger than 200 km in diameter lose their central peak and are called basins. Thallasoids are distinguished into a separate group - large crater formations, close in size to round lunar seas, but unlike them, having a bright bottom, not filled with dark lava.

Notes

APPEARANCE

Like all planets and their moons, the Moon mainly shines by reflected sunlight. Usually the part of the Moon that is illuminated by the Sun is visible. The exception is the periods near the new moon, when the light reflected from the Earth weakly illuminates the dark side of the Moon, creating a picture of "the old Moon in the arms of the young."

The brightness of the full moon is 650 thousand times less than the brightness of the sun. The full moon reflects only 7% of the sunlight falling on it. After periods of intense solar activity, individual places on the lunar surface may faintly glow under the action of luminescence.

On the visible side of the Moon - the one that is always turned towards the Earth - dark areas are striking, called by astronomers of the past the seas (in Latin mare). Because of the relatively flat surface, the seas were chosen for the landing of the first expeditions of astronauts; studies have shown that the seas have a dry surface covered with small porous lava fragments and rare stones. These large dark areas of the Moon are in stark contrast to the bright mountain regions, whose rugged surfaces reflect light much better. The spacecraft that circled the Moon showed, contrary to expectations, that there are no large seas on the far side of the Moon and therefore it does not look like the visible side.

Moon illusion.

The Moon looks much larger near the horizon than it does high up in the sky. This is an optical illusion. Psychological experiments have shown that the observer subconsciously adjusts his perception of the size of an object depending on the size of other objects in the field of view. The moon appears smaller when high in the sky and surrounded by large empty space; but when it is near the horizon, its size is easily compared to the distance between it and the horizon. Under the influence of this comparison, we unconsciously reinforce our impression of the size of the moon.

Phases.

The phases of the moon arise as a result of a change in the relative position of the Earth, the Moon and the Sun. For example, when the Moon is between the Sun and the Earth, its side facing the Earth is dark and therefore almost invisible. This moment is called the new moon, because, starting from it, the moon seems to be born and becomes visible more and more. Having passed a quarter of its orbit, the Moon shows an illuminated half of the disk; while they say that it is in the first quarter. With the passage of half of the orbit of the Moon, the entire side facing the Earth becomes visible - it enters the phase of the full moon.

The Earth also goes through different phases when viewed from the Moon. For example, on a new moon, when the disk of the Moon is completely dark to an observer on Earth, an astronaut on the Moon sees a completely illuminated "full Earth". Conversely, when we see a full moon on Earth, a "new earth" can be observed from the Moon. In the first and third quarters, when people on Earth see half of the lunar disk illuminated, astronauts on the Moon will also see the illuminated half of the Earth's disk.

MOTION

The main influence on the movement of the Moon is exerted by the Earth, although the much more distant Sun also affects it. Therefore, the explanation of the motion of the Moon becomes one of the most difficult problems of celestial mechanics. The first acceptable theory was proposed by Isaac Newton in his Beginnings(1687), where the law of universal gravitation and the laws of motion were published. Newton not only took into account all the perturbations of the lunar orbit known at that time, but also predicted some effects.

Orbit characteristics.

The time required for the Moon to make a complete 360° orbit around the Earth is 27 days 7 hours 43.2 minutes. But all this time, the Earth itself moves around the Sun in the same direction, so the mutual position of the three bodies is repeated not through the orbital period of the Moon, but after about 53 hours after it. Therefore, the full moon occurs every 29 days 12 hours 44.1 minutes; this period is called the lunar month. Each solar year contains 12.37 lunar months, so 7 out of 19 years have 13 full moons. This 19-year period is called the "Metonic cycle" because in the 5th c. BC. the Athenian astronomer Meton proposed this period as the basis for the reform of the calendar, however, it did not take place.

The distance to the moon is constantly changing; Hipparchus knew this in the 2nd century. BC. He determined the average distance to the Moon, obtaining a value quite close to the modern one - 30 Earth diameters. The distance to the Moon can be determined by various methods, for example, by triangulation from two remote points on Earth, or using modern technology: by the time it takes a radar or laser signal to travel to the Moon and back. The average distance at perigee (the closest point of the Moon's orbit to the Earth) is 362,000 km, and the average distance at apogee (the farthest point of the orbit) is 405,000 km. These distances are measured from the center of the earth to the center of the moon. The apogee point and with it the entire orbit revolves around the Earth in 8 years and 310 days.

Incline.

The plane of the Moon's orbit is inclined to the plane of the Earth's orbit around the Sun - the ecliptic - by about 5 °; therefore the Moon never moves more than 5° from the ecliptic, always being in or near the zodiacal constellations. The points at which the lunar orbit crosses the ecliptic are called nodes. A solar eclipse can only occur on a new moon and only when the moon is near a node. This happens at least twice a year. In other cases, the Moon passes in the sky above or below the Sun. Lunar eclipses only occur on full moons; in this case, as in the case of solar eclipses, the Moon must be near the node. If the plane of the lunar orbit were not inclined to the plane of the earth's orbit, i.e. if the Earth and the Moon moved in the same plane, then at each new moon there would be a solar eclipse, and at each full moon there would be a lunar eclipse. The line of nodes (a straight line passing through both nodes) rotates around the Earth in the opposite direction to the movement of the Moon - from east to west with a period of 18 years 224 days. This period is closely connected with the saros cycle, which is 18 years 11.3 days and determines the time interval between identical eclipses.

Earth-Moon system.

Of course, it is not entirely correct to talk about the movement of the Moon around the Earth. More precisely, both of these bodies revolve around their common center of mass, which lies below the surface of the Earth. An analysis of the Earth's oscillations showed that the mass of the Moon is 81 times less than the mass of the Earth.

The gravitational pull of the Moon causes the tides to ebb and flow on Earth. Tidal movements as a result of friction slow down the rotation of the Earth, increasing the duration of the Earth's day by 0.001 s per century. Since the angular momentum of the Earth-Moon system is conserved, the deceleration of the Earth's rotation leads to the slow removal of the Moon from the Earth. However, in the current era, the distance between the Earth and the Moon is decreasing by 2.5 cm per year due to the complex interaction of the Sun and planets with the Earth.

The moon always faces the Earth on one side. A detailed analysis of its gravitational field showed that the Moon is deformed in the direction of the Earth, but the distortion of its shape is too great for the modern tidal effect. This distortion is considered a "frozen tide" left over from when the Moon was closer to the Earth and experienced a stronger tidal influence from it than now. But this bulge can also represent the inhomogeneity of the internal structure of the moon. The preservation of both the ancient tidal bulge and the asymmetric distribution of mass requires the presence of a solid shell, since under the influence of its own gravity the liquid body takes on a spherical shape. Some experts believe that in general the entire moon is solid inside. To do this, it must be cold enough. The results of seismic experiments indicate that the inner regions of the Moon are indeed weakly heated.

Gravitational measurements carried out in lunar orbit by the American apparatus Lunar Orbiter partially confirmed the inhomogeneity of the internal structure of the Moon: in some large seas, areas of dense matter concentration were found, called mascons (from the words "mass" and "concentration"). They arose where large masses of dense rocks are surrounded by relatively light rocks.

SURFACE DETAILS

Although the Moon is always turned to the Earth on one side, we have the opportunity to see a little more than half of its surface. When the Moon is at the apex of its oblique orbit, a normally hidden area near its south pole can be observed, and the area around the north pole becomes visible when the moon reaches its lowest point in the orbit. In addition, additional areas can be observed on the eastern and western limb (edge) of the Moon, since it rotates around its axis at a constant speed, and the speed of its movement around the Earth varies from maximum at perigee to minimum at apogee. As a result, wiggles - librations - of the Moon are observed, which allow you to see 59% of its surface. Areas that are completely impossible to see from Earth are photographed using spacecraft.

The oldest complete map of the visible hemisphere of the Moon is given in Selenography, or Description of the Moon(1647) J. Hevelia. In 1651, G. Riccioli proposed that the details of the lunar surface should be given the names of prominent astronomers and philosophers. Modern selenography - the science of the physical characteristics of the Moon - began with a detailed and detailed map of the Moon (1837) by W. Beer and I. Mödler.

Photographing the moon began in 1837 and reached its highest point in Systematic Photographic Atlas of the Moon(J. Kuiper et al., 1960). It shows regions of the Moon illuminated by sunlight from at least four different angles. The best resolution in photographs taken from the Earth's surface is 0.24 km. Five Lunar Orbiters, successfully launched in 1966 and 1967, obtained from lunar orbit an excellent and almost complete photographic map of the Moon. Therefore, even the details of the far side of the Moon are now known with ten times better resolution than the details of its visible side in 1960. Detailed maps of the Moon were produced by NASA and are available from the US Government Records Office.

New details of the lunar surface get their names. For example, the Ranger 7 automatic vehicle fell on an unnamed site in 1964; now this site is called the Known Sea. Large craters photographed on the far side of the Moon by Luna-3 are named after Tsiolkovsky, Lomonosov and Joliot-Curie. Before a new name can be officially assigned, it must be approved by the International Astronomical Union.

Three main types of formations can be distinguished on the Moon: 1) seas - vast, dark and rather flat areas of the surface covered with basalt lava; 2) continents - bright raised areas filled with many large and small round craters, often overlapping; 3) mountain ranges, such as the Apennines, and small mountain systems, such as the one that surrounds the Copernicus crater.

Seas.

The largest of the dozen seas on the visible side of the Moon is the Sea of Rains with a diameter of approx. 1200 km. The ring of individual peaks at its bottom and the surrounding chain of mountains with radial rays indicate that the Sea of Rains arose as a result of a huge meteorite or comet nucleus hitting the Moon. Its bottom is not perfectly flat, but is crossed by undulating ripples, which can be seen at a small angle of incidence of sunlight. These ripples, with their accompanying color difference, indicate that the lava has poured here more than once, but possibly as a result of several successive impacts.

Photographs from lunar orbit have revealed a more impressive basin than the Sea of Rains. This is the Eastern Sea, which is partially visible from the Earth on the left limb of the Moon, but only the Lunar Orbiter showed its true appearance. The central dark plain of this sea is rather small, but it serves as the center of a large number of circular and radial mountain ranges. The central basin is surrounded by two almost perfectly concentric chains of mountains with a diameter of 600 and 1000 km, and rocks in the form of complex radial formations are ejected beyond the outer mountain range for more than 1000 km.

The almost circular contour of the Sea of Clarity also indicates a collision, but on a smaller scale. Other seas also appear to have been filled with lava by one or more collisions, the later of which destroyed the crater created by the first collision.

Other large cratered areas, not destroyed by a powerful collision, could become seas after a powerful outpouring of lava. Examples of this kind are the Ocean of Storms and the Sea of Tranquility, which have irregular contours and contain partially submerged ancient craters. Small but inexplicable differences in colors are characteristic of different seas. For example, the central area of the bottom of the Sea of Clarity has a reddish tint typical of older, deeper layers, while the outer part of this sea and the neighboring Sea of Tranquility have a bluish tint.

The strange absence of dark seas on the far side of the Moon suggests that they do not form all that often. Probably, the entire system of seas was formed as a result of only a few collisions. For example, the filling of the Ocean of Storms and the Sea of Clouds could occur from one blow in the area of the Sea of Rains. Perhaps this side of the Moon was first turned away from the Earth. When the resulting impact craters filled with heavy lava and gave rise to mascons, the resulting asymmetry in the distribution of mass allowed the Earth's gravity to turn the Moon and permanently fix its hemisphere with the seas in the direction of our planet.

The nature of the surface of the moon.

The most important result of the Apollo program was the discovery of a powerful crust near the Moon. At the landing site of Apollo 14 near Fra Mauro crater, the crust is about 65 km thick. The moon is covered with loose clastic material - regolith, the layer of which has a thickness of 3 to 15 m. Therefore, solid rock is almost never exposed, with the exception of a few young large craters. The regolith is mainly composed of small particles of various sizes, usually around 25 µm. It is a mixture of pieces of stone, spherules (microscopic spheres) and fragments of glass. The material is very porous and compressible, but strong enough to support the weight of an astronaut.

The rock samples delivered by Apollo 11, -12 and -15 turned out to be mostly basaltic lava. This marine basalt is rich in iron and, less commonly, titanium. Although oxygen is undoubtedly one of the main elements of the rocks of the lunar seas, lunar rocks are significantly poorer in oxygen than their terrestrial counterparts. Of particular note is the complete absence of water, even in the crystal lattice of minerals. The basalts delivered by Apollo 11 have the following composition:

The samples delivered by Apollo 14 represent a different type of crust, a breccia rich in radioactive elements. Breccia is an agglomerate of stone fragments cemented by small particles of regolith. The third type of lunar crust samples is aluminum-rich anorthosites. This rock is lighter than dark basalts. In terms of chemical composition, it is close to the rocks studied by Surveyor-7 in the mountainous area near the Tycho crater. This rock is less dense than basalt, so that the mountains formed by it seem to float on the surface of denser lava.

All three rock types are represented in large samples collected by the Apollo astronauts; but the certainty that they are the main types of rock that make up the crust is based on the analysis and classification of thousands of small fragments in soil samples collected from various places on the lunar surface.

craters

- one of the characteristic features of the moon. Tens of thousands of craters can be seen with a medium sized telescope. The largest of them look like flat areas surrounded by a wall. Craters such as Grimaldi, Shikkard and Tsiolkovsky (on the far side of the Moon) have a diameter of about 250 km and a smooth lava bottom. Rangers, Surveyors, and Apollo observations uncovered many small craters, down to the size of tiny potholes. While most of the craters are rounded, some of the largest are polygonal in shape. To a terrestrial observer, the strong contrast of light and shadow gives the impression of a very uneven surface of the Moon; in fact, the walls of the craters are very gentle.

Most of the craters were formed as a result of impacts on the surface of the Moon by meteorites and cometary nuclei at an early stage in its history. Larger primary craters arose from a direct hit of cosmic bodies, and many secondary craters were formed after the fall of debris thrown out by the first explosions. The secondary craters are concentrated around the primary ones and are often arranged in pairs or have an elongated shape. Impact craters on Earth are very similar to those on the moon. But erosion destroys terrestrial craters, and on the Moon, in the absence of air, wind and rain - the main causes of erosion - very old formations remain.

Some craters may be the result of volcanic activity. These are surprisingly regular funnel-shaped pits with dazzling white walls under the full moon. The fact that they are sometimes located in rows, probably above seismic fissures or on mountain tops, only strengthens the volcanic hypothesis proposed by the American astronomer of Dutch origin J. Kuiper. Infrared observations made during total lunar eclipses have revealed hundreds of unusually warm spots; as a rule, they coincide with bright young craters.

Since most of the craters are located in bright continental areas, they must be older than the seas. According to Kuiper, the first craters formed after the seas acquired a smooth lava bottom. The surface later melted, but not enough to fill the craters with lava, although volcanic eruptions are visible. Near a full moon, Tycho and a few solitary craters such as Copernicus and Kepler become dazzling white, and long white bands called "rays" radiate from them. These craters have irregular central slides and a lot of small debris inside the shaft. Since their rays lie on top of other lunar formations, radiant craters must be the youngest on the Moon. Ranger 7 showed that the rays are rows of numerous white secondary craters.

Observations of changes in the lunar surface are highly debatable. Usually these are apparent changes due to differences in the angle of incidence of the sun's rays. Astronomers have long argued whether Linnaeus - a bright spot in the Sea of Clarity - was once a crater, as indicated on the old lunar map in the work of Riccioli. In 1958, the Soviet astronomer N.A. Kozyrev observed something that probably represented an outburst of gas in the Alfons crater. After some period of distrust, astronomers became interested in the possibility of active volcanic activity on the Moon. An analysis of disparate observations shows that the areas of expected activity are concentrated along the edges of the seas.

Other features.

The mountain ranges so familiar to us on Earth are quite rare on the Moon. The main mountain chains on the visible side of the Moon (the Apennines, the Alps and the Caucasus) were, of course, shaped by the collision that created the Sea of Rains. Concentric chains of mountains surround some other seas. Some mountains along the southern edge of the Moon are comparable in height to Everest. Wrinkles formed by compression are visible in the interior of most seas. Often they have a stepped structure with parallel but slightly offset segments. Sometimes they look like a rather complex braid.

Fissures and steep canyons 1–2 km wide often stretch for hundreds of kilometers almost in a straight line. Their depth ranges from one to several hundred meters; more than a thousand of them are catalogued. These rupture cracks in the lava crust are often parallel to the edges of the seas. Some of them resemble the meanders of earthly rivers.

Wrinkles and cracks, as well as wide and narrow valleys form a giant network. The radial features of the relief associated with the Sea of Rains form the largest grid system on the Moon. Some researchers believe that the grid system reflects intralunar stress and contraction processes, but others think that this is the result of external influences associated with collisions that created the seas.

Found on the moon and many other features. The most grandiose fault is the Straight Wall, which extends into the Sea of Clouds for about 170 km; it is a steep escarpment about 300 m high. rupture zones, where a significant portion of the surface began to sink. Several small extinct volcanoes have been discovered at the bottom of the seas. Another curious feature of the lunar surface is small lava domes. Cm. also