Three articles devoted to our natural satellite were published at once. During its lifetime, the Moon has been bombarded by two different populations of asteroids or comets, and its surface is geologically more complex than previously thought. In addition, after processing data from the Lunar Reconnaissance Orbiter (LRO), scientists compiled a topographic map of our satellite, which marked 5,185 craters with a diameter of more than 20 km.
The first paper describes the results obtained using the LOLA (Lunar Orbiter Laser Altimeter) laser altimeter, designed to compile a high-resolution three-dimensional map of the lunar surface and installed on the Lunar Reconnaissance Orbiter (LRO).
Previous maps of the Moon were not as detailed: viewing angles and lighting conditions created certain difficulties in consistently determining the size and depth of lunar craters. Thanks to the LOLA altimeter, scientists were able to calculate the height of lunar craters with unprecedented accuracy. The instrument sends laser pulses to the lunar surface, measuring the time it takes for the pulse to bounce off and back. The accuracy of the measurement is simply amazing: the device determines the height of the terrain with an accuracy of 10 cm. Thanks to this, scientists have compiled an unprecedentedly detailed topographic map of our satellite.
“By examining the resulting map, it is possible to determine which craters formed earlier, and which later, on the surface of the Moon that had already been changed before. After analyzing the size distribution of craters, we came to the conclusion that all meteorites and comets that collided with the Moon can be conditionally divided into two groups: the first, earlier bombardment of our satellite, significantly exceeded the second in terms of the percentage of large bodies. The moment of transition from one group to another roughly corresponds to the formation of the East Sea (the lunar sea at the western edge of the visible disk of the satellite), which is estimated to be 3.8 billion years old, ”explains study author James Head of Brown University.
Any large meteorite can radically change the history of the planet. Astronomers find on the surfaces of planets such as, for example, Mercury, Mars and even Venus, traces of ancient craters hundreds and thousands of kilometers across. The Moon is the most convenient object of study, as it is close to us and retains evidence of cosmic bombardment, which on Earth has long been erased due to the displacement of tectonic plates, water and wind erosion. “The moon is like the Rosetta stone for understanding the history of the bombardment of the Earth,” says Head. “Having dealt with the surface of the Moon, we can give an explanation for the fuzzy footprints that we found on our planet.”
In two other studies, scientists describe data obtained from the DLRE (The Diviner Lunar Radiometer Experiment) radiometer, which is also installed on the LRO. This device registers the thermal radiation of the lunar surface, which makes it possible to estimate the composition of lunar rocks. According to the authors of the study, the surface of the moon can be represented in the form of anorthositic highlands, which are rich in calcium and aluminum, as well as basalt seas, where the concentration of elements such as iron and magnesium is increased. Both of these crustal rocks are considered primary, that is, they are formed directly as a result of the crystallization of the mantle substance. On the whole, DLRE observations confirm the legitimacy of this division: most regions of the lunar surface can be attributed to one of the indicated types.
However, the data from the probe forced scientists to recognize that some lunar hills are very different from others. For example, the DLRE quite often recorded an elevated sodium content, which is not typical for the "ordinary" anorthositic crust. Of greatest interest was the discovery in several areas of minerals rich in silica, which correspond to evolved rocks other than primitive anorthosite. Here, an increased content of thorium was previously determined, which is another evidence of the “evolution” of rocks.
As the scientists note in their report, DLRE was unable to register traces of “pure” mantle matter, which, as some studies have shown, should come to the surface in some places. Even when studying the Aitken South Pole Basin - the largest, oldest and deepest impact crater - scientists have not found any evidence of the presence of material from the mantle. Perhaps there really are no outcrops of mantle material on the Moon. Or maybe their area is too small for the DLRE to detect them.
> > > Dimensions of the Moon
What is the size of the moon- Earth satellite. Description of mass, density and gravity, real and apparent size, supermoon, illusion of the Moon and comparison with the Earth in the photo.
The Moon is the brightest object in the sky (after the Sun). To a terrestrial observer, it seems gigantic, but this is only because it is located closer than other objects. In size, it occupies 27% of the earth (ratio 1: 4). If compared with other satellites, then ours is in 5th place in terms of size.
The average lunar radius is 1737.5 km. The value doubled will be the diameter (3475 km). The equatorial circle is 10917 km.
The area of the Moon is 38 million km 2 (this is less than any total area of the continent).
Mass, density and gravity
- Mass - 7.35 x 10 22 kg (1.2% of the earth). That is, the Earth exceeds the lunar mass by 81 times.
- Density - 3.34 g / cm 3 (60% of the earth). According to this criterion, our satellite ranks second, losing to Saturn's moon Io (3.53 g/cm3).
- The force of attraction grows only up to 17% of the earth, so 100 kg there will turn into 7.6 kg. That is why astronauts can jump so high on the lunar surface.
Supermoon
The moon wraps around the Earth not in a circle, but in an ellipse, so sometimes it is much closer. The closest distance is called perigee. When this moment coincides with the full moon, we get a super moon (14% larger and 30% brighter than usual). It repeats every 414 days.
horizon illusion
There is an optical effect that makes the apparent size of the moon appear even larger. This happens when it rises behind distant objects on the horizon. This trick is called the moon illusion or the Ponzo illusion. And although it has been observed for many centuries, there is no exact explanation yet. In the photo you can compare the size of the Moon and the Earth, as well as the Sun with Jupiter.
One of the theories suggests that we are accustomed to watching the clouds at a height and understand that on the horizon they are miles away from us. If the clouds on the horizon reach the same size as those overhead, then, despite the distance, we remember that they must be huge. But since the satellite appears at the same size as overhead, the brain automatically aims to zoom in.
Not everyone agrees with this formulation, so there is another hypothesis. The moon appears close to the horizon because we can't compare its size to trees and other terrestrial objects. Without comparison, it seems larger.
To check for an illusion of the moon, you need to put your thumb on the satellite and compare the size. When she returns to height again, then repeat this method again. It will be the same size as before. Now you know how big the moon is.
Brief information
The Moon is the Earth's natural satellite and the brightest object in the night sky. The force of gravity on the Moon is 6 times less than on Earth. The difference between day and night temperatures is 300°C. The rotation of the Moon around its axis occurs at a constant angular velocity in the same direction in which it revolves around the Earth, and with the same period of 27.3 days. That is why we see only one hemisphere of the Moon, and the other, called the far side of the Moon, is always hidden from our eyes.Moon phases. The numbers are the age of the moon in days. Details on the moon depending on the equipment Due to its proximity, the Moon is a favorite object for astronomy lovers, and deservedly so. Even the naked eye is enough to get a lot of pleasant impressions from contemplating our natural satellite. For example, the so-called "ash light" that you see when observing the thin crescent of the Moon is best seen in the early evening (at dusk) on a waxing or early morning on a waning Moon. Also, without an optical device, interesting observations can be made of the general outlines of the Moon - the seas and land, the ray system surrounding the Copernicus crater, etc. By pointing binoculars or a small low-power telescope at the Moon, you can study the lunar seas, the largest craters and mountain ranges in more detail. Such an optical device, not too powerful at first glance, will allow you to get acquainted with all the most interesting sights of our neighbor. As the aperture grows, the number of visible details also increases, which means that there is an additional interest in studying the Moon. Telescopes with a lens diameter of 200 - 300 mm make it possible to examine fine details in the structure of large craters, to see the structure of mountain ranges, to examine many furrows and folds, and to see unique chains of small lunar craters. Table 1. Capabilities of various telescopes
|
Lens diameter (mm) |
Magnification (x) |
permissive |
The diameter of the smallest formations, |
| 50 | 30 - 100 | 2,4 | 4,8 |
| 60 | 40 - 120 | 2 | 4 |
| 70 | 50 - 140 | 1,7 | 3,4 |
| 80 | 60 - 160 | 1,5 | 3 |
| 90 | 70 - 180 | 1,3 | 2,6 |
| 100 | 80 - 200 | 1,2 | 2,4 |
| 120 | 80 - 240 | 1 | 2 |
| 150 | 80 - 300 | 0,8 | 1,6 |
| 180 | 80 - 300 | 0,7 | 1,4 |
| 200 | 80 - 400 | 0,6 | 1,2 |
| 250 | 80 - 400 | 0,5 | 1 |
| 300 | 80 - 400 | 0,4 | 0,8 |
Of course, the above data is primarily the theoretical limit of the capabilities of various telescopes. In practice, it is often somewhat lower. The culprit for this is mainly the restless atmosphere. As a rule, on the vast majority of nights, the maximum resolution of even a large telescope does not exceed 1"". Be that as it may, sometimes the atmosphere "settles down" for a second or two and allows observers to squeeze the maximum possible out of their telescope. For example, on the most transparent and calm nights, a telescope with a lens diameter of 200 mm is able to show craters with a diameter of 1.8 km, and a 300 mm lens - 1.2 km. Necessary equipment The Moon is a very bright object that, when viewed through a telescope, often simply dazzles the observer. To reduce brightness and make observations more comfortable, many amateur astronomers use an ND filter or a variable density polarizing filter. The latter is more preferable, as it allows you to change the level of light transmission from 1 to 40% (Orion filter). Why is it convenient? The fact is that the amount of light coming from the moon depends on its phase and the magnification applied. Therefore, when using a conventional ND filter, you will occasionally encounter a situation where the image of the moon is either too bright or too dark. The variable density filter is free from these disadvantages and allows you to set a comfortable brightness level if necessary.
Orion Variable Density Filter. Demonstration of the possibility of selecting the filter density depending on the phase of the moon
Unlike the planets, observations of the Moon usually do not use color filters. However, the use of a red filter often helps to highlight areas of the surface with a lot of basalt, making them darker. The red filter also helps to improve the image in unstable atmospheres and attenuate moonlight. If you are serious about exploring the moon, you need to get a lunar map or atlas. On sale you can find the following cards of the moon: "", as well as a very good "". There are also free editions, however, in English - "" and "". And of course, be sure to download and install "Virtual Atlas of the Moon" - a powerful and functional program that allows you to get all the necessary information to prepare for lunar observations.What and how to observe on the moon
When is the best time to see the moon?
At first glance it seems absurd, but the full moon is not the best time to observe the moon. The contrast of lunar features is minimal, making it almost impossible to observe them. During the "lunar month" (the period from new moon to new moon), there are two most favorable periods for observing the moon. The first begins shortly after the new moon and ends two days after the first quarter. This period is preferred by many observers, since the visibility of the Moon falls on the evening hours.
The second favorable period begins two days before the last quarter and lasts almost until the new moon. These days, the shadows on the surface of our neighbor are especially long, which is clearly visible on the mountainous terrain. Another plus of observing the Moon in the phase of the last quarter is that in the morning the atmosphere is calmer and cleaner. Due to this, the image is more stable and clear, which makes it possible to observe finer details on its surface.
Another important point is the height of the moon above the horizon. The higher the Moon, the less dense layer of air overcomes the light coming from it. Therefore, there is less distortion and better image quality. However, the height of the moon above the horizon varies from season to season.
table 2. The most and least favorable seasons for observing the moon in various phases
When planning your observations, be sure to open your favorite planetarium program and determine the hours of the best visibility.
The moon moves around the earth in an elliptical orbit. The average distance between the centers of the Earth and the Moon is 384,402 km, but the actual distance varies from 356,410 to 406,720 km, due to which the apparent size of the Moon varies from 33" 30"" (at perigee) to 29" 22"" (apogee). ).
Of course, you should not wait until the distance between the Moon and the Earth is minimal, just note that at perigee one can attempt to consider those details of the lunar surface that are at the limit of visibility.
Starting observations, point your telescope to any point near the line that divides the moon into two parts - light and dark. This line is called the terminator, being the boundary of day and night. During the growing moon, the terminator indicates the place of sunrise, and during the waning - sunset.
When observing the Moon in the terminator region, you can see the tops of the mountains, which are already illuminated by the sun's rays, while the lower part of the surface surrounding them is still in shadow. The scenery along the terminator line changes in real time, so if you spend a few hours at the telescope observing this or that lunar landmark, your patience will be rewarded with an absolutely stunning sight.
What to see on the moon
craters- the most common formations on the lunar surface. They got their name from the Greek word for bowl. Most of the lunar craters are of impact origin, i.e. formed as a result of the impact of a cosmic body on the surface of our satellite.
Moon Seas- dark areas that stand out clearly on the lunar surface. At its core, the seas are lowlands that occupy 40% of the entire surface area visible from the Earth.
Look at the moon on a full moon. The dark spots that form the so-called "face on the moon" are nothing more than lunar seas.
Furrows- lunar valleys, reaching a length of hundreds of kilometers. Quite often, the width of the furrows reaches 3.5 km, and the depth is 0.5–1 km.
Folded veins- in appearance they resemble ropes and, apparently, are the result of deformation and compression caused by the sinking of the seas.
mountain ranges- lunar mountains, the height of which ranges from several hundred to several thousand meters.
Domes- one of the most mysterious formations, since their true nature is still unknown. At the moment, only a few dozen domes are known, which are small (usually 15 km in diameter) and low (several hundred meters), round and smooth elevations.
How to observe the moon
As mentioned above, observations of the Moon should be carried out along the terminator line. It is here that the contrast of lunar details is maximum, and thanks to the play of shadows, unique landscapes of the lunar surface open up.
When looking at the Moon, experiment with magnification and find the most appropriate for the given conditions and for this object.
In most cases, three eyepieces will suffice for you:
1) An eyepiece that gives a small increase, or the so-called search one, which allows you to comfortably view the full disk of the moon. This eyepiece can be used for general sightseeing, lunar eclipse viewing, and lunar excursions for family and friends.
2) An eyepiece of medium power (about 80-150x, depending on the telescope) is used for most observations. It will also be useful in unstable atmospheres where high magnification is not possible.
3) A powerful eyepiece (2D-3D, where D is the diameter of the lens in mm) is used to study the lunar surface in detail at the limit of the telescope's capabilities. Requires good atmospheric conditions and complete thermal stabilization of the telescope.
Your observations will become more productive if they are focused. For example, you can start your study with the list " ", compiled by Charles Wood. Also pay attention to the series of articles "" that talk about lunar sights.
Another fun activity can be looking for tiny craters visible at the limit of your equipment.
Make it a habit to keep an observation diary in which you regularly record the conditions of observation, the time, the phase of the moon, the state of the atmosphere, the magnification used, and a description of the objects you see. Such records can be accompanied by sketches.
10 most interesting lunar objects
(Sinus Iridum) T (moon age in days) - 9, 23, 24, 25 
It is located in the northwestern part of the moon. Viewable with 10x binoculars. In a telescope at medium magnification is an unforgettable sight. This ancient 260 km diameter crater has no rim. Numerous small craters dot the remarkably flat bottom of Rainbow Bay.
(Copernicus) T - 9, 21, 22 
One of the most famous lunar formations is visible with a small telescope. The complex includes the so-called system of rays, extending for 800 km from the crater. The crater is 93 km in diameter and 3.75 km deep, making sunrises and sunsets over the crater a breathtaking sight.
(Rupes Recta) T - 8, 21, 22 
A tectonic fault 120 km long, easily visible in a 60 mm telescope. A straight wall runs along the bottom of a ruined ancient crater, traces of which can be found on the east side of the fault.
(Rümker Hills) T - 12, 26, 27, 28 
A large volcanic dome visible with a 60mm telescope or large astronomical binoculars. The hill has a diameter of 70 km and a maximum height of 1.1 km.
(Apennines) T - 7, 21, 22 
The mountain range is 604 km long. Easily visible with binoculars, but its detailed study requires a telescope. Some peaks of the ridge rise above the surrounding surface for 5 or more kilometers. In some places, the mountain range is crossed by furrows.
(Plato) T - 8, 21, 22 
Visible even with binoculars, the Plato crater is a favorite among astronomers. Its diameter is 104 km. The Polish astronomer Jan Hevelius (1611-1687) named this crater "Great Black Lake". Indeed, through binoculars or a small telescope, Plato looks like a large dark spot on the bright surface of the moon.
Messier and Messier A
(Messier and Messier A) T - 4, 15, 16, 17 
Two small craters that require a telescope with a 100 mm objective lens to observe. Messier has an oblong shape measuring 9 by 11 km. Messier A is slightly larger - 11 by 13 km. To the west of the craters Messier and Messier A, two bright beams 60 km long stretch.
(Petavius) T - 2, 15, 16, 17 
Despite the fact that the crater is visible in small binoculars, a truly breathtaking picture opens up in a telescope with a high magnification. The domed bottom of the crater is dotted with furrows and cracks.
(Tycho) T - 9, 21, 22 
One of the most famous lunar formations, famous mainly due to the giant system of rays surrounding the crater and extending for 1450 km. The rays are perfectly visible through small binoculars.
(Gassendi) T - 10, 23, 24, 25 
The oval crater, elongated for 110 km, is accessible for observation with 10x binoculars. The telescope clearly shows that the bottom of the crater is dotted with numerous crevices, hills, and there are also several central hills. A careful observer will notice that the walls near the crater have been destroyed in some places. At the northern end is the small crater Gassendi A, which, together with its older brother, resembles a diamond ring.
Apennines
Sea Plato Cope Sea riais
clarity Kepler iho. e "n s ..-
The relief of the lunar hemisphere "facing the Earth" is clearly visible even with a small telescope. Vast dark rounded and relatively even lowlands were obtained as early as the 11th century. the name of the seas: the Sea of Tranquility, the Sea of Clarity, etc. (Fig. 200). Their sizes are from 200 to 1200 km across. The largest lowland, over 2000 km long, is called the Ocean of Storms. The smooth surface of the seas is covered with dark matter, including hardened lava, once erupted from the lunar interior. The Ocean of Storms and the largest seas are visible to the naked eye in the form of dark spots.
Light areas - continents occupy over 60% of the visible surface of the Moon. The continents are covered with both individual mountains and mountain ranges. So, the Sea of Rains is limited from the northeast by the Alps, from the east - by the Caucasus. The height of the mountains is different, some mountain peaks reach 8 km.
The mountainous regions are covered with many ring structures - craters, in a smaller number they are also found in the seas. The sizes of craters are from 1 m to 250 km. Many craters are named after scientists: Archimedes, Hipparchus, etc. Such large craters as Tycho, Copernicus, Kepler have divergent light ray structures.
According to modern concepts, most of the craters were formed when large meteorites, asteroids and comets collided with the lunar surface.
Questions for self-examination
1. “It determines the change of seasons and the presence of thermal zones
on the ground?
2. What is the phenomenon of precession?
3. What is the physical nature of the greenhouse effect?
4. What is the nature of lunar craters?
Task 50
Using the law of universal gravitation, calculate the mass of the Earth, knowing that O \u003d 6.67 10 c N ° mz, "kgz, i \u003d 9 8 mTsz.
Laboratory work M 9
Determining the size of lunar craters
The purpose of the work is to learn how to measure the sizes of various formations on the surface. sty of the moon.
Instruments and materials: photograph of the visible surface of the Moon (see Fig. 200), millimeter ruler.
Order of performance of work 1. Remember or write out from the reference book angular and linear diameters of the Moon. 2. Find some formations in the photograph of the Moon: the Sea of Rains, the Sea of \u200b\u200bClarity, the Apennine mountains, Tycho crater, Plato crater. 3. Estimate the measurement error of the millimeter ruler. 4. Determine the linear scale of the photograph of the lunar surface. Mas "ptab is equal to the ratio of the diameter of the moon in km and the diameter of the moon in mm. b. Measure the maximum and minimum sizes of lunar formations. Record the measurement results in table 28. 6. Calculate the linear dimensions of these formations and write down the results in table 28.