Apart from the scattering of stars, the moon is undoubtedly the decoration of the night sky. Due to the combination of its size and distance from Earth, it is the second brightest celestial object and can completely obscure the solar disk during an eclipse. It is not surprising that the night star has been attracting the attention of mankind for more than one millennium.
If the Earth did not have the Moon, many things would have turned out differently:
- the day would be much shorter;
- the change of seasons and the climate would be characterized by instability;
- less pronounced ebb and flow would occur;
- the appearance on the planet of life in its present form would be questionable.
Moon diameter
The average value of the moon's diameter is not too large by cosmic standards, the number is 3474.1 km. This is approximately half the distance from Moscow to Vladivostok.
Nevertheless, the Moon is ranked fifth place in size among the natural satellites of the planets of the solar system:
- Ganymede.
- Titanium.
- Callisto.
- Moon.
But even when comparing the sizes of satellites in relation to their planets, the moon has no equal. With a diameter of a quarter of the earth, it ranks first. Moreover, it is larger than Pluto.
What is the distance from the Earth to the Moon
The quantity is not constant. On average, between the centers of the planet and its natural satellite 384 400 kilometers. In this space, about 30 more Earths would fit, and light needs 1.28 seconds to overcome this distance.
What if the nearest celestial body could be reached by car at a speed of 95 km / h? Considering that the entire distance is about 10 circles of the Earth, the journey would take the same amount of time as 10 detours of the planet along the equator. That is a little less than six months. So far, the fastest way to the Moon was covered by the New Horizons interplanetary station, which on its way to Pluto crossed the satellite's orbit eight and a half hours after launch.
The moon's orbit is not a perfect circle, and an oval (ellipse), inside which the Earth is. At different points, it is located closer to or further from the planet. Because of this, when rotating around a common center of mass with the Earth, the satellite is either approaching or moving away. So, the fewest kilometers are separated by celestial bodies when the night star is in an orbital place called perigee. At the point designated as the apogee, the satellite is farthest from the planet. The minimum distance is 356 400 km, and the maximum is 406 700 km. So the distance fluctuates from 28 to 32 earth diameters.
The first close to correct estimates of the distance to the "neighbor" of the Earth were obtained in the II century. n. e. Ptolemy. In our time, thanks to modern reflective devices installed on the satellite, the distance was measured most accurately (with an error of several cm). To do this, a laser beam is directed at the moon. Then they note during what period it will return to the Earth, reflected. Knowing the speed of light and the time it took it to reach the sensors, it’s easy to calculate the distance.
How to visually estimate the size of the moon and its distance from the earth
Earth's diameter is about 4 times the Lunar diameter, and the volume is 64 times. The distance to the night star is approximately 30 times the planet's diameter. To visually assess the distance from the Earth to its satellite and compare their sizes, you need two balls: a basketball and a tennis one. Diameter ratio:
- Earth (12,742 km) and the Moon (3474.1 km) - 3.7: 1;
- standard basketball (24 cm) and tennis (6.7 cm) - 3.6: 1.
The values \u200b\u200bare pretty close. Thus, if the Earth were the size of a basketball, then its satellite would be a tennis one.
You can ask people to imaginethat the Earth is a basketball, and the Moon is a tennis ball, and to show how far the satellite is from the planet on this scale. Most are likely to assume a distance of 30 cm to a few steps.
In fact, to show the correct distance, you have to move a little more than seven meters. So, between the planet and its satellite, on average, 384 400 km, which is about 30 Earths or, respectively, 30 basketball balls. Multiplying the diameter of the sports equipment by 30 gives the result of 7.2 m. This is approximately 9 male or 11 female steps.
The apparent size of the moon from Earth
360 angular degrees - the entire circumference of the celestial sphere. At the same time, the night star occupies about half of one degree on it (on average 31 minutes) - this is the angular (visible) diameter. For comparison: the width of the index finger nail at arm's length is about one degree, that is, two moons.
By a unique coincidence, the apparent sizes of the Sun and the Moon for the inhabitants of the Earth are almost the same. This is possible due to the fact that the diameter of the nearest star 400 times the diameter of the satellite, but the daylight is located the same amount of times further. Due to this coincidence, among all the planets orbiting the Sun, only on Earth can we observe its total eclipse.
Is the size of the moon changing
Of course, the true diameter of the satellite remains the same, but the apparent size may vary. So, The moon appears noticeably larger during sunrise and sunset.... When the night star is low above the horizon, the distance to the observer does not decrease, but, on the contrary, slightly increases (by the radius of the Earth). The visual effect, it would seem, should be the opposite. There is no single answer to explain the reason for the illusion. We can only say with confidence that this beautiful phenomenon owes its existence only to the peculiarities of the work of the human brain, and not, for example, to the influence of the Earth's atmosphere.
The distance between the Moon and the Earth periodically changes from maximum (at apogee) to minimum (at perigee). The apparent diameter of the satellite varies along with the distance: from 29.43 to 33.5 arc minutes. Thanks to this, not only total eclipses are possible, but also annular (when the apparent size of the moon at apogee is less than the solar disk). Approximately once every 414 days, the full moon coincides with the passage of perigee. At this time, the largest night star can be observed. The phenomenon has received a rather loud name supermoon, but the apparent diameter at this moment is only 14% larger than usual. The difference is very small, and a simple observer will not notice the difference.
Thanks to precise measurements distance, scientists were able to detect a relatively slow but constant increase in the distance between the Earth and its satellite. The speed at which the moon is receding - 3.8 cm per year - is too slow to notice a significant decrease in the apparent size of the star. Human nails grow at about the same rate. Nevertheless, after 600 million years the Moon will be so far away and, accordingly, will decrease for terrestrial observers that total solar eclipses will remain in the past.
Its useful to note, what a satellite of the earth, formed according to modern theory from the collision of a planet with a large object 4.5 billion years ago, was originally 10-20 times closer. However, then there was no one to admire the sky, decorated with a luminary 10-20 times larger than it is now.
Video
You can understand how far the Moon is from the Earth by watching this video.
Measurements of the distance from the Earth to the Moon were carried out in ancient times: the Greeks tried to do this repeatedly.
This information was necessary for a person to obtain a complete picture of the concept of the Universe.
In addition to calculating the distance to the Earth's satellite, the ancient Greeks carried out calculations to calculate its radius.
Over time, technological progress has developed and today all measurements are known to man.
For a long time, people were interested in what space and the moon are - since time immemorial it has been a natural satellite of our planet.
People were interested in how far it was and how long to fly to it, using various calculations for this.
Today, it is unrealistic to measure distance by methods used in everyday life.
For this, trigonometric formulas and calculations are used.
Consider how the ancient people defined this indicator, recalling that it is measured from the center of the satellite:
- The first who tried to get through to the truth was Aristarchus of Samos.
On the basis of geometric equations and indicators obtained using goniometric instruments, the scientist conducted a study.
To begin with, he calculated the difference in distance to the satellite and the Sun, and then multiplied this result by the radius of the Earth. His calculations showed that the distance is 509680 in kilometers.
- In the 2nd century BC, the astronomer Hipparchus of Nicea also began calculations.
He carried out observations of the Moon at different phases and came to the conclusion that the distance to the Earth will be equal to 382260 kilometers.
Based on angular measurements, Hipparchus found out that during the eclipse, the Sun and the Moon have the same indicators.
After that, he calculated the difference and derived a formula by which he determined the average distance.
Average distance in kilometers
It is impossible to indicate the exact indicators of the distance in kilometers: this is due to the elliptical shape of the orbit along which the satellite moves.
This suggests that for some time it moves away from the planet, after which it approaches again.
Note! There are several numerical results that describe the mileage of the distance to a celestial satellite.
The actual dimensions can vary within 15%, which is associated with different points of the satellite.
The fullest Moon is much closer to the Earth than when it goes through the growth phase.
Known indicators will help you find out the distance that scientists have measured:
Flight time
To date, a large number of flights have already been completed in order to judge how long it takes to travel to the satellite.
Scientists made calculations based on rocket speed and astronaut observations.
Here are some numbers:
- The slowest flight will take 1 year 1 month and 2 weeks, which has been proven experimentally.
In 2003, a lunar probe was launched on the basis of a revolutionary ion engine station called ESA SMART-1.
- The average flight took 5 days when the Chinese satellite Chang'e-1 was sent into orbit in 2007, using standard rocket engines.
- The manned flight with a man lasted 3 days, 3 hours and 49 minutes, when the Americans first stepped onto the lunar surface in 1969 - the Saturn 5 spacecraft took off from a platform in Florida.
- The shortest route was mastered by the Americans in the New Horizons project: the satellite's speed is 58 thousand kilometers.
To overcome the pull of the sun, Nasa used tremendous acceleration.
Important! The Soviet satellite Luna-1 made its first flight, it passed 500 kilometers from the Moon, reaching the place in 2 days.
Today, space travel companies around the world offer short or long duration trips to the moon.
Any calculations made by a person were surrounded by many interesting facts and stories. Measuring space and distance to the Moon is not without such cases.
Here are some interesting examples related to the history of calculating the flight time, the distance from the Earth to the satellite:
- According to legend, the Moon was formed from the collision of the planet Earth with another planet. Then an orbit was formed, from which a yellow-white satellite was formed.
- The satellite is always facing the planet with one side.
- The largest crater is called Bailey, with a diameter of 295 kilometers.
- During one of the expeditions, the American Apollo 6 brought several hundred kilograms of lunar soil to Earth.
- Being on Earth and looking at the sky, it seems that the Moon and the Sun have the same size.
- There is no atmosphere on the moon, so night falls there immediately, without the gradual extinction of light.
- The force of attraction on a satellite is of the least importance - it is 6 times less than the force of attraction on Earth.
- On the surface of the satellite there is a monument to the fallen cosmonauts - this is a 10 centimeters figure made of aluminum.
- Over the years, the Moon has significantly moved away from the Earth: this happens every year by 4 centimeters.
- The minimum distance at the nearest points from the Moon to Mars is 55 million 399 thousand kilometers.
It is known that regular flights to Mars are planned in the future, but it is much more convenient to carry them out from the surface of the satellite.
Calculating the distance to the moon helps flight planners to reliably calculate the amount of fuel and money spent on the flight.
Useful video
From time immemorial, the moon has been a constant satellite of our planet and the closest celestial body to it. Naturally, a person always wanted to go there. But how far is to fly there and how far is it?
The distance from the Earth to the Moon is theoretically measured from the center of the Moon to the center of the Earth. It is impossible to measure this distance by the usual methods used in everyday life. Therefore, the distance to the earth's satellite was calculated using trigonometric formulas.
Like the Sun, the Moon experiences constant motion in the earth's sky near the ecliptic. However, this movement is significantly different from the movement of the Sun. So the planes of the orbits of the Sun and the Moon differ by 5 degrees. It would seem that as a result of this, the trajectory of the moon in the earth's sky should be similar in general terms to the ecliptic, differing from it only in a shift of 5 degrees:
In this, the movement of the Moon resembles the movement of the Sun - from west to east, in the opposite direction to the daily rotation of the Earth. But in addition, the moon moves across the earth's sky much faster than the sun. This is due to the fact that the Earth revolves around the Sun in about 365 days (Earth year), and the Moon around the Earth in only 29 days (lunar month). This difference became an incentive to break down the ecliptic into 12 zodiacal constellations (in one month the Sun shifts along the ecliptic by 30 degrees). During the lunar month, there is a complete change in the phases of the moon:
In addition to the trajectory of the Moon, the factor of strong elongation of the orbit is also added. The eccentricity of the Moon's orbit is 0.05 (for comparison, for the Earth, this parameter is 0.017). The difference from the circular orbit of the Moon leads to the fact that the apparent diameter of the Moon is constantly changing from 29 to 32 arc minutes.
In a day, the Moon is shifted relative to the stars by 13 degrees, in an hour by about 0.5 degrees. Modern astronomers often use the lunar coverings to estimate the angular diameters of stars near the ecliptic.
What determines the movement of the moon
An important point in the theory of the motion of the moon is the fact that the orbit of the moon in outer space is not unchanging and stable. Due to the relatively small mass of the Moon, it is subject to constant disturbances from more massive objects of the Solar System (primarily the Sun and the Moon). In addition, the Moon's orbit is influenced by the flattening of the Sun and the gravitational fields of other planets in the Solar System. As a result, the magnitude of the eccentricity of the Moon's orbit fluctuates between 0.04 and 0.07 with a period of 9 years. The result of these changes was such a phenomenon as a supermoon. Supermoon is an astronomical phenomenon during which the full moon is several times larger in angular size than usual. So during the full moon on November 14, 2016, the moon was at a record close distance since 1948. In 1948, the Moon was 50 km closer than in 2016.
In addition, fluctuations in the inclination of the lunar orbit to the ecliptic are observed: by about 18 arc minutes every 19 years.
What is equal
Spacecraft will have to spend a lot of time on the flight to the earth's satellite. You cannot fly to the moon in a straight line - the planet will orbit away from the destination point, and the path will have to be corrected. At a second cosmic speed of 11 km / s (40,000 km / h), the flight will theoretically take about 10 hours, but in reality it will take longer. This is because the ship at the start gradually increases its speed in the atmosphere, bringing it to a value of 11 km / s in order to escape from the Earth's gravitational field. Then the ship will have to slow down when approaching the moon. By the way, this speed is the maximum that modern spacecraft have managed to achieve.
America's notorious 1969 flight to the moon took 76 hours, according to official figures. NASA's New Horizons spacecraft managed to reach the Moon the fastest - in 8 hours 35 minutes. True, he did not land on the planetoid, but flew past - he had another mission.
Light from the Earth to our satellite will reach very quickly - in 1.255 seconds. But flying at light speeds is still out of the realm of fantasy.
You can try to imagine the path to the moon in the usual values. On foot at a speed of 5 km / h, the road to the moon will take about nine years. If you go by car at a speed of 100 km / h, then it will take 160 days to get to the earth's satellite. If planes flew to the moon, the flight to it would last about 20 days.
How astronomers in ancient Greece calculated the distance to the moon
The moon became the first celestial body to which it was possible to calculate the distance from the Earth. It is believed that astronomers were the first to do this in ancient Greece.
They have tried to measure the distance to the Moon since time immemorial - the first to try to do this was Aristarchus of Samos. He estimated the angle between the Moon and the Sun at 87 degrees, so it turned out that the Moon is 20 times closer to the Sun (the cosine of an angle equal to 87 degrees is 1/20). The angle measurement error resulted in a 20-fold error, today it is known that this ratio is actually 1 in 400 (the angle is approximately 89.8 degrees). The large error was caused by the difficulty of estimating the exact angular distance between the Sun and the Moon using primitive astronomical instruments of the ancient world. Regular solar eclipses by this time have already allowed the ancient Greek astronomers to conclude that the angular diameters of the Moon and the Sun are approximately the same. In this regard, Aristarchus concluded that the Moon is 20 times smaller than the Sun (in fact, about 400 times).
Aristarchus used a different method to calculate the size of the Sun and Moon relative to the Earth. We are talking about observing lunar eclipses. By this time, ancient astronomers had already guessed the reasons for these phenomena: the Moon is eclipsed by the shadow of the Earth.
The diagram above clearly shows that the difference in the distances from the Earth to the Sun and to the Moon is proportional to the difference between the radii of the Earth and the Sun and the radii of the Earth and its shadow at the distance of the Moon. At the time of Aristarchus, it was already possible to estimate that the radius of the moon is approximately 15 arc minutes, and the radius of the earth's shadow is 40 arc minutes. That is, the size of the moon turned out to be about 3 times smaller than the size of the earth. From here, knowing the angular radius of the Moon, it was easy to estimate that the Moon is located about 40 Earth diameters from the Earth. The ancient Greeks could only roughly estimate the size of the Earth. So Eratosthenes of Cyrene (276 - 195 BC), based on the differences in the maximum height of the Sun above the horizon in Aswan and Alexandria during the summer solstice, determined that the radius of the Earth is close to 6287 km (modern value 6371 km). If we substitute this value into Aristarchus's estimate of the distance to the Moon, then it will correspond to approximately 502 thousand km (the current value of the average distance from the Earth to the Moon is 384 thousand km).
A little later, a mathematician and astronomer of the 2nd century BC. e. Hipparchus of Nicaea calculated that the distance to the earthly satellite is 60 times greater than the radius of our planet. His calculations were based on observations of the movement of the moon and its periodic eclipses.
Since at the moment of the eclipse the Sun and the Moon will have the same angular dimensions, then according to the rules of similarity of triangles, the ratio of the distances to the Sun and the Moon can be found. This difference is 400 times. Applying these rules again, only in relation to the diameters of the Moon and the Earth, Hipparchus calculated that the diameter of the Earth is 2.5 times greater than the diameter of the Moon. That is, R l \u003d R s / 2.5.
At an angle of 1 ', one can observe an object whose dimensions are 3483 times smaller than the distance to it - this information was known to everyone in the time of Hipparchus. That is, with an observed radius of the moon of 15 ′, it will be 15 times closer to the observer. Those. the ratio of the distance to the moon to its radius will be 3483/15 \u003d 232 or S l \u003d 232R l.
Accordingly, the distance to the Moon is 232 * R s / 2.5 \u003d 60 Earth radii. This turns out to be 6 371 * 60 \u003d 382 260 km. The most interesting thing is that measurements made with modern instruments confirmed the correctness of the ancient scientist.
Now the measurement of the distance to the moon is carried out using laser devices, which can be measured with an accuracy of several centimeters. In this case, measurements take place in a very short time - no more than 2 seconds, during which the Moon moves away in orbit about 50 meters from the point of sending the laser pulse.
The evolution of methods for measuring the distance to the moon
Only with the invention of the telescope, astronomers were able to obtain more or less accurate values \u200b\u200bof the parameters of the Moon's orbit and the correspondence between its size and the size of the Earth.
A more accurate method for measuring the distance to the moon appeared in connection with the development of radar. The first radar of the Moon was carried out in 1946 in the USA and Great Britain. Radar made it possible to measure the distance to the moon with an accuracy of several kilometers.
An even more accurate method of measuring the distance to the moon has become laser ranging. For its implementation in the 1960s, several corner reflectors were installed on the Moon. It is interesting to note that the first laser ranging experiments were carried out even before the installation of corner reflectors on the lunar surface. In 1962-1963, several experiments were carried out at the Crimean Observatory of the USSR on laser ranging of individual lunar craters using telescopes with a diameter of 0.3 to 2.6 meters. These experiments were able to determine the distance to the lunar surface with an accuracy of several hundred meters. In 1969-1972, the Apollo astronauts delivered three corner reflectors to the surface of our satellite. Among them, the most perfect was the reflector of the Apollo 15 mission, since it consisted of 300 prisms, while the other two (the Apollo 11 and Apollo 14 missions) of only one hundred prisms each.
In addition, in 1970 and 1973, the USSR delivered to the lunar surface two more French corner reflectors on board the self-propelled vehicles Lunokhod-1 and Lunokhod-2, each of which consisted of 14 prisms. The first of these reflectors has an extraordinary history. During the first 6 months of operation of the Lunokhod with a reflector, it was possible to carry out about 20 sessions of laser ranging. However, then, due to the unfortunate position of the lunar rover, it was not possible to use the reflector until 2010. Only the images of the new LRO spacecraft helped to clarify the position of the lunar rover with the reflector, and thus resume the sessions with it.
In the USSR, the largest number of laser ranging sessions was carried out with the 2.6-meter telescope of the Crimean Observatory. Between 1976 and 1983, 1400 measurements were made with this telescope with an error of 25 centimeters, then observations were stopped due to the curtailment of the Soviet lunar program.
In total, from 1970 to 2010, approximately 17 thousand high-precision laser ranging sessions were conducted in the world. Most of them were associated with the Apolonna 15 corner reflector (as mentioned above, it is the most perfect - with a record number of prisms):
Of the 40 observatories that are capable of laser ranging of the Moon, only a few can perform high-precision measurements:
Most of the ultra-precise measurements were made with a 2-meter telescope at the McDonald Observatory in Texas:
At the same time, the most accurate measurements are performed by the APOLLO instrument, which was installed on the 3.5-meter telescope of the Apache Point Observatory in 2006. The accuracy of its measurements reaches one millimeter:
Evolution of the Moon and Earth system
The main goal of increasingly accurate measurements of the distance to the Moon is to try to better understand the evolution of the Moon's orbit in the distant past and in the distant future. To date, astronomers have come to the conclusion that in the past the Moon was several times closer to the Earth, and also had a much shorter rotation period (that is, it was not tidal captured). This fact confirms the impact version of the formation of the Moon from the ejected matter of the Earth, which prevails in our time. In addition, the tidal effect of the moon leads to the fact that the speed of rotation of the earth around its axis gradually slows down. The rate of this process is an increase in the Earth's day every year by 23 microseconds. In one year, the Moon moves away from the Earth by an average of 38 millimeters. It is estimated that if the Earth-Moon system survives the transformation of the Sun into a red giant, then in 50 billion years the Earth's day will be equal to the lunar month. As a result, the Moon and Earth will always be turned to each other by only one side, as is now observed in the Pluto-Charon system. By this time, the Moon will move away to about 600 thousand kilometers, and the lunar month will increase to 47 days. In addition, it is assumed that the evaporation of the Earth's oceans in 2.3 billion years will lead to an acceleration of the Moon's removal process (Earth's tides significantly slow down the process).
In addition, calculations show that in the future the Moon will again begin to approach the Earth due to the tidal interaction with each other. When approaching the Earth by 12 thousand km, the Moon will be torn apart by tidal forces, the fragments of the Moon form a ring like the well-known rings around the giant planets of the Solar System. Other well-known satellites of the Solar System will repeat this fate much earlier. So Phobos is assigned 20-40 million years, and Triton is about 2 billion years old.
Every year the distance to the earth's satellite increases by an average of 4 cm. The reasons are the movement of the planetoid in a spiral orbit and the gradually decreasing power of the gravitational interaction of the Earth and the Moon.
Theoretically, all the planets of the solar system can be placed between the Earth and the Moon. If you add up the diameters of all the planets, including Pluto, you get a magnitude of 382,100 km.
The moon is a spherical rocky space body. It lacks the atmosphere and any signs of life. Compared to our planet, of which it is the only satellite. The satellite's diameter is about a quarter of the Earth's diameter. Long before the beginning of all kinds of research, people realized that the moon is full of mysteries and secrets.
In contact with
It is on a par with the largest natural satellites of the planets in the solar system. The density of the soil is relatively low, and samples taken from the surface for detailed analysis, confuse scientists to this day. According to the theory of origin, it was "born" about 4.1 billion years ago.
Traffic
The average distance from the moon to the Earth is 384,400 km, this figure roughly includes 60 radii of our planet. Depending on the moment of movement of the only satellite of the Earth in an elliptical orbit, the degree of its proximity to the planet and the dimensions visible to the observer change. When at perigee, the satellite is separated from the Earth by 363104 kilometers. When a heavenly body reaches its climax, the shortest distance between the centers of the Earth and the Moon is equal to 406,696 kilometers. The range of the distance difference reaches 43592 km.
When observing the movement of this celestial body across the firmament, one can fall under the influence of optical illusion. When it is high and surrounded by infinite space, its dimensions are perceived to be much smaller than it really is. In close proximity to the Earth's horizon, the Moon may appear to have a large diameter.
Due to the fact that the satellite is now approaching the planet, then moving away from it, the brightness of the moon's surface also varies. Research proves that the satellite does not create a glow, but reflects about seven percent of the scattered sunlight. This feature is characterized by a regolith layer arising from collisions with meteorites. Debris particles range in size from the smallest to the largest and can cover a surface from a few microns to tens of meters.
What does the movement depend on
The movement of the Moon in its orbit is due to the influence on it by the attraction of the Earth and the Sun. Moreover, the Sun attracts it to itself to a much greater extent than our planet. In addition to the brightest star in the solar system, the motion of the moon is a combination of many parameters:
The movement of the Moon in its orbit can be compared to a spiral that gradually unwinds.
Distance between Earth and Moon
Distance between Earth and Moon the value is not constant. The ancient scientist Hipparchus of Nicea in the second century BC was able to calculate this distance. He got a figure equal to thirty earthly diameters, that is, 384,000 kilometers.
The size of the diameter was able to measure another ancient Greek mathematician and astronomer Eratosthenes of Cyrene. He set the pole upright near the library building and measured the length of the shadow cast from it. Then he determined the smallest angle that a sunbeam forms when falling on a pole. The result is a degree equal to seven. With the knowledge that on the day of the summer solstice in the city of Siena, the Sun is at its zenith, and the distance from Siena to Alexandria is 5000 stades, Eratosthenes concluded: 5000 stades is 7 degrees of the Earth's meridian. The full meridian is 360 degrees, or roughly 250,000 stades.
How to find out the distance to the satellite
There are several measurement methods distance from Earth to Moon:
- The easiest one is based on their angular dimensions.
These dimensions are the same, since during a total solar eclipse, the solar disk is completely obscured by the lunar disk. An ordinary splinter is suitable for measurement. If you place a splinter in an outstretched hand, then the ratio of its width to length to the eye is the angular size of the Moon in radians. This value is 0.0087. Converting radians to degrees gives approximately 0.5. Knowing the radius of the Earth and the angular size of our satellite, it is easy to find out distance to a celestial body... By geometric calculations, there is a distance equal to 30 diameters of our planet.
- Using the laser ranging method.
A laser beam is directed from the Earth's surface to the reflective reflectors installed on the Moon by astronauts more than forty years ago. It moves at a known speed of light and, having reached the reflector, comes back. The beam path is approximately one second. Scientists record a specific time and calculate the exact distance to our satellite. This method of measurement helped to establish what changes the trajectory of movement away from the planet by several centimeters per year.
- Triangulation method (from two points equidistant on the Earth's surface).
Average distance to the moon: wikipedia
The closest point of the Moon's orbit is located on average at a distance of 362,000 kilometers. The most distant point of the lunar orbit is at a distance of 405,000 kilometers.
At least twice a year on a new moon, when the satellite approaches the node as much as possible (the point of intersection with the ecliptic), a solar eclipse takes place. The rest of the time, its movement is carried out under the Sun or above it. On full moons, lunar eclipses occur, and Earth's natural satellite must also be near the node.
A straight line connecting the nodes wraps around our planet every 18 years and 224 days. The direction of rotation in this case is opposite to the course of the moon.
Afterword
Over a century, the duration of the earth's day increases by one thousandth of a second. This phenomenon causes celestial body closest to Earth as a result of the action of the forces of gravity. In the world's oceans, ebbs and flows occur due to the gravitational attraction of the moon, and these processes slow down the earth's rotation.
The gravitational field influenced the shape of the celestial body. On the side facing the Earth, deformation is present, although it is possible that the latter arose due to the structure of the inner layers of the satellite.
The impact on the Moon, produced by the Earth and the Sun, modifications in the trajectory of its movement in an elliptical orbit, millions of years later, will move the mysterious celestial body away and optically reduce it. Total solar eclipses will also become a legend.