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Distance between Earth and Moon: the closest and farthest distances between cosmic bodies. Find out how many planets can fit between the Earth and the Moon in the photo.
In short, then distance from Earth to Moon the average is 384403 km. But it is important to know a few nuances. It is not for nothing that we used the word “average”, because the Moon passes along an elliptical path and changes its distance.
The closest and farthest distance from the Earth to the Moon
At the closest point, the distance from the Earth to the Moon is 363,104 km, and at maximum distance – 406,696 km. You see a difference of 43592 km, which is quite a lot. This changes its apparent size by 15%. It also affects luminosity, because it will appear 30% brighter in full phase and at closest approach. This moment is called a supermoon.
This video was released in 2011 to display the geocentric phase, axial position angle, libration, and apparent lunar diameter over a year.
But how did we even manage to determine the distance between the Moon and Earth? Well, it all depends on the computation time. The ancient Greeks relied on simple geometric formulas. They for a long time tracked the change in shadows and guessed that it should be 108 times the diameter of the body. This is where the ideas about lunar and solar eclipses arose.
Scientists have found that the shadow is about 2.5 times the width of the moon. The object itself has sufficient parameters to periodically block the Sun from us. Knowing the earth's diameter and the triangle formula, they calculated the distance to be 397,500 km. Not entirely accurate, but these are amazing indicators for that time.
Now we use millimeter measurement - calculating the time it takes for a signal to travel from the Earth to an object. Thanks to the Apollo mission, we were able to do this with a satellite. More than 40 years ago, astronauts installed special reflecting mirrors on its surface, into which laser beams were sent from our planet. We get a weak return, but it’s enough to get the most accurate number possible.
The speed of light is 300,000 km/s, so it takes just over a second to cover the distance. Then the same amount is spent on returns. This technique also helped to understand that every year the satellite moves away by 3.8 cm, and after billions of years it will visually appear smaller than the star. Yes, you will have to say goodbye to your favorite eclipses.
If we remember the scale of our planets (especially gas giants), then you are surprised that this could be real. To understand, let's take a look at the planetary diameters:
- Mercury – 4879 km
- Venus – 12104 km
- Mars – 6771 km
- Jupiter – 139822 km
- Saturn – 116464 km
- Uranium – 50724 km
- Neptune – 49244 km
- Total: 380008 km
The distance between us and the satellite is 384,400 km. It turns out that we also save 4392 km. What to do with the remainder? Well, you can add Pluto, which extends over 2092 km, as well as some other dwarf planet. Of course, physically they would not be able to rotate side by side, but the possibility itself is surprising.
384,467 kilometers - this is the distance that separates us from the nearest major cosmic body, from our only natural satellite- Moons. This begs the question: how did scientists know about this? After all, you really can’t walk from the Earth to the Moon with a meter in your hands!
However, attempts to measure the distance to the Moon have been made since ancient times. The ancient Greek scientist Aristarchus of Samos tried to do this, the same one who first expressed the idea of heliocentric system! He also knew that the Moon, like the Earth, has the shape of a ball and does not emit its own light, but shines from the reflected light of the sun. He suggested that at a time when the Moon for an observer from Earth looks like a half-disk. Between it, the Earth and the Sun, a right triangle is formed, in which the distance between the Moon and the Sun and between the Moon and the Earth are the legs, and the distance between the Sun and the Earth is the hypotenuse.
Therefore, you need to find the angle between the directions to the Moon and the Sun, and then using the appropriate geometric calculations you can calculate how many times the Earth-Moon leg is shorter than the Earth-Sun hypotenuse. Alas, the technology of that time did not make it possible to accurately determine the time when the Moon occupies a position at the top of the mentioned right triangle, and in such calculations a small error in measurements leads to large errors in the calculations. Aristarchus was mistaken almost 20 times: it turned out that the distance to the Moon was 18 times less than the distance to the Sun, but in reality it was 394 times less.
Another ancient Greek scientist, Hipparchus, obtained a more accurate result. He, however, adhered to geocentric system but the reason lunar eclipses understood correctly: the Moon falls into the shadow of the Earth, and this shadow has the shape of a cone, the top of which is located away from the Moon. The outline of this shadow can be observed during an eclipse on the disk of the Moon, and by the curve of the edge one can determine in what ratio it is located cross section and the size of the Moon itself. Given that the Sun is much further away than the Moon, it was possible to calculate how far away the Moon would have to be for the shadow to shrink to that size. Such calculations led Hipparchus to the conclusion that the distance from the Earth to the Moon is 60 Earth radii, or 30 diameters. The diameter of the Earth was calculated by Eratosthenes - translated into modern measures length 12,800 kilometers - thus, according to Hipparchus, the distance from the Earth to the Moon is 384,000 kilometers. As we can see, this is very close to the truth, especially considering that he had nothing but simple goniometer instruments!
In the 20th century, the distance from the Earth to the Moon was measured with an accuracy of three meters. To do this, several reflectors were delivered to the surface of our cosmic “neighbor” about 30 years ago. A focused laser beam is sent to these reflectors from the Earth, the speed of light is known, and the distance to the Moon is calculated from the time it takes the laser beam to travel “there and back.” This method is called laser ranging.
When talking about the distance from the Earth to the Moon, it should be remembered that we are talking about an average distance, because the Moon’s orbit is not circular, but elliptical. At the point farthest from the Earth (apogee), the distance between the Earth and the Moon is 406,670 km, and at the closest point (perigee) – 356,400 km.
Agree, Space, alien planets, star clusters- this is a very, very exciting topic. For example, what is the distance to the Moon? Surely many of you have asked this question at some point! Or what is its origin? And what does it consist of? Or maybe someone even lives there? Well, at least microorganisms? The distance to the Moon has always interested humanity.
Development of ideas about the Moon
This celestial object has attracted the attention of people since ancient times. And at the dawn of the development of astronomy, the Moon became one of the first objects for observation and study. Information about attempts to trace the pattern of its movement across the firmament and explain them goes back to the Sumerian, Babylonian cultures, ancient Chinese and Egyptian civilizations. And, of course, to ancient Greece. The first known attempt to calculate the distance to the Moon (and also to the Sun) was made by Aristarchus of Samos.
on our satellite of the first people, did it in a little more than three days. However, the problem here is not only the speed of the device itself, but the need to calculate the movement of the Moon, fly along a certain arc and land in the required place. Thus, the path follows an arc rather than a straight line. The record time for a man-made spacecraft to reach the satellite is currently 8 hours and 35 minutes. It was the New Horizons spacecraft launched by NASA.
Is the distance from the Earth to the Moon increasing?
Yes! This is true. Our satellite moves as if in a spiral orbit. And every year the distance to it increases by about 4 centimeters. This is quite a bit for the individual observer. However, our distant ancestors will see the Moon much less. Moreover, weakening gravitational interaction with it will entail a decrease in the activity of ebbs and flows on Earth and will significantly transform climatic conditions on our planet.
In ancient times, after a collision, fragments of Theia were thrown into Earth's orbit. Then, under the influence of gravity, they formed a celestial body - the Moon. The orbit of the Moon at that time was much closer than it is today and was at a distance of 15-20 thousand km. In the sky, its apparent size was then 20 times larger. Since the collision, the distance of the Moon from the Earth has increased and today it averages 380 thousand kilometers
Even in antiquity, people tried to calculate the distance to visible celestial bodies. So the ancient Greek scientist and philosopher Aristarchus of Samos determined the distance to the Moon to be 18 times closer to the sun. In reality, this distance is 400 times less.
More accurate were the results of calculations by Hipparchus, according to which the distance to the moon was equal to 30 Earth diameters. His calculations were based on Eratosthenes' calculations of the circumference of the Earth. By today's standards, this was 40,000 km, which is the diameter of the Earth at 12,800 km. This corresponds to the actual modern parameters.
Modern data on the orbit of the Moon
Today science has fairly accurate methods for determining distances to space objects. During the astronauts' stay on the Moon, they installed a laser reflector on its surface, according to which scientists high accuracy The size of the orbit and the distance to the Earth are now being determined.The shape of the Moon's orbit is slightly elongated into an oval. The closest point to the Earth (perigee) is at a distance of 363 thousand km, the farthest (apogee) is 405 thousand km. The orbit also has a significant eccentricity of 0.055. Because of this, its apparent size in the sky is quite different. Also, the plane of the Moon’s orbit is inclined by 5° to the plane of the Earth’s orbit.
In orbit, the Moon moves at a speed of 1 km/s and circles the Earth in 29 days. Its location in the sky shifts to the right every night, looking from the side northern hemisphere, and for observers southern hemisphere- to the left. For them, the visible disk of the Moon appears upside down.
The Moon is 400 times closer than the Sun and just as much smaller in diameter, so on Earth there are observed solar eclipses exactly matching the dimensions of the disks of the luminary and the satellite. And because of the elliptical orbit, the Moon at the farthest point is smaller in diameter and thanks to this it is visible annular eclipses. The Moon gradually continues to move away from the Earth by 4 cm per century, so in the distant future, people will no longer have to observe such eclipses as now.