What is a total eclipse of the moon. Eclipse of the sun and moon

It's called a lunar eclipse a natural phenomenon, during which the moon enters the region of the earth's shadow. When the lunar eclipse comes the Moon with the Sun and the Earth should be located on the line at the same time. It turns out that the Moon is blocked from the Sun with the help of the Earth. This means that an eclipse is only possible on a full moon. At this time, you can see the Moon, which is completely or partially shaded from the Earth. It is possible to observe the eclipse from that part of our planet that is located above the horizon.

Partial lunar eclipse

The diameter of the earth's shadow is 2.5 times that of the moon, which is why the earth's shadow covers the entire disk of the moon. In a situation where this happens, the eclipse is total. If there is a partial immersion of the moon in the earth's shadow, then such an eclipse is considered partial.

In those situations where the line of the Moon with the Sun and the Earth is far from ideal, a variant is possible in which the eclipse phase does not occur. It is also possible that the earth's shadow will touch the edge of the lunar disk, it will be covered with penumbra.

The duration of the phases of any eclipse, partial or total, depends directly on the location of all 3 of the above celestial bodies. The longest duration of a lunar eclipse is 108 minutes. The brightness of the lunar disk during a total lunar eclipse also depends on the same reason. There are cases when the Moon is not visible at all, and it also happens that the Moon is so bright that observers do not even believe that a lunar eclipse has occurred.

The penumbra, which is present around the cone of the earth's shadow, can partially obscure the Sun. When the Moon begins to pass through this area, but has not entered the shadow, a penumbral eclipse occurs. The brightness of the moon becomes less, but not much. Such a decrease in brightness cannot be seen with the naked eye, only devices can fix this.

Even when the lunar eclipse is total, the moon does not disappear at all, turning dark red. There is an explanation for this: with the onset of a total eclipse, the rays of the Sun illuminate the Moon further. These rays shine tangentially onto the earth's surface, refract, and then dissipate in the earth's atmosphere.

The atmosphere of the Earth is able to absorb the short-wavelength spectral parts of blue and blue hues, but at the same time pass the reds without any problems. They reach the lunar surface at the onset of an eclipse. This phenomenon has the same nature that is observed in the coloring of the western part of the sky in a pale pink color of the sun's rays.

Instruction

As you know, the moon is the only natural satellite Earth. In the earth's sky, it is the brightest object after the Sun. In its movement in the orbit of the Moon, in different periods time, it turns out to be between our planet and the Sun, then on the other side of the Earth. The Earth is constantly illuminated by the Sun and casts a cone-shaped shadow into outer space, the diameter of which at the minimum distance to the Moon is 2.5 times its diameter.

The plane of the Moon's orbit is at an angle of about 5° to the plane of the ecliptic.
If precession is taken into account earth's axis and plane lunar orbit and take into account the perturbations caused by the Sun and other planets solar system, it becomes clear that the motion of the Moon in its orbit changes periodically.

At some moments in time, the Sun, Earth and Moon may be on the same or almost on the same straight line, and the earth's shadow will partially or completely cover the Moon. Such an astronomical event is called a lunar eclipse. If the lunar disk is completely submerged in the region of the earth's shadow, a total lunar eclipse occurs. With partial immersion, a partial eclipse is observed. The phase of a total eclipse may not occur at all.

Even with a total eclipse, the lunar disk is visible in the sky. The moon is illuminated by the sun's rays passing tangentially to earth's surface. The earth's atmosphere is most permeable to the rays of the red-orange spectrum. Therefore, during an eclipse, the lunar disk becomes dark red and not so bright. In 2014 there will be 2 total lunar eclipses - April 15 and October 8. It is clear that the eclipse can be observed only in that part the globe, where the Moon, at the time of its passage through the region of the shadow, is above the horizon. The maximum duration of a total lunar eclipse is 108 minutes.

During a partial eclipse, the earth's shadow covers only part of the lunar disk. From the Earth, the observer will see a somewhat blurred, due to the scattering of light by the atmosphere, the boundary between the illuminated and shadowed parts of the Moon. Shaded areas take on a reddish tint.

As you know, light rays are able to bend around obstacles. This phenomenon is called diffraction. Thus, around the cone of full shadow in space there is a partially illuminated area - penumbra. Direct sunlight does not penetrate there. If the Moon passes through this area, a penumbral eclipse is observed. The brightness of its glow decreases slightly. As a rule, the eclipse is even impossible to notice without special instruments. For astronomers penumbral eclipses are of no interest.

Moon eclipse- a phenomenon not as rare as the solar one, perhaps that is why it was not so feared, but no less interesting. The causes of solar and lunar eclipses are similar: both are explained by the ratio of the diameters of the Sun and the Moon to their distance from the Earth. The difference between a solar and a lunar eclipse is that in the first case, the Moon obscures the Earth, and in the second, the Earth obscures the Moon (so that during a lunar eclipse on Earth, you can observe the sun on our only satellite).

In order for a lunar eclipse to take place, first of all, the moon must be visible - i.e. it cannot happen on a new moon, but the ideal case is, of course, a full moon. The full moon, as you know, happens every month. In addition, it is necessary that during the full moon the Earth be close to the lunar node - the point at which the lunar orbit intersects with the ecliptic (the circle of the sky along which the Sun moves during the year for an observer located on Earth). If the planes of the orbits of the Earth and the Moon coincided completely, each full moon would be accompanied by an eclipse (in other words, we would never really see the full moon), but the plane of the lunar orbit is tilted with respect to the earth by 5 degrees - a little, but enough to make the shadow from In most cases, the earth did not hit the “point”. This happens about twice a year, maximum - three, it also happens that this will not happen even once in a year, solar eclipses happen from two to five a year. It turns out that lunar eclipses occur even less often than solar ones - but they can be observed much more often ... why is this happening?

The fact is that the Earth is larger than the Moon, and the cone of its shadow is much wider than the cone of the Moon, so if a lunar eclipse has already occurred, then it can be seen on the entire half of the planet, where the Moon is visible at that time. During a solar eclipse, the shadow of our satellite “passes” far from the entire surface of our planet, it will touch the area where you live, or it won’t touch it - that’s how lucky. That is why you can live your life and never see a solar eclipse, and everyone has seen a lunar eclipse at least once. By the way, the ancient Greek astronomers calculated the ratio of the sizes of the Moon and the Earth relatively accurately for their era based on the ratio of the frequency of lunar and solar eclipses!

It is noteworthy that during the eclipse the moon does not disappear from the sky, it is still visible - but it looks unusual: it becomes blurry and dark red. The ancient inhabitants of Mesopotamia came up with a very original explanation for this phenomenon: the Moon turns red with blood when the goddess Ishtar begins menstruation (theoretically, this should suggest that her female cycle is very, very long ... but the goddess must be somewhat different from ordinary Earthly women !). Today we know the true reason for this phenomenon. The fact is that the earth's shadow does not completely cover the moon - part sunlight still reaches it, making it possible to shine with reflected light, but the rays of the Sun go tangentially to our planet, passing through its atmosphere. Our atmosphere scatters the blue and green parts of the spectrum, but it passes the red and orange well - this is the part of the spectrum that the Moon “gets” during an eclipse.

But even when you know it blood red moon makes an eerie impression - so lunar eclipses also scared people. So, once the Athenian army was so frightened by the lunar eclipse that the soldiers threw down their weapons and fled, so that Syracuse won without a fight (why the Syracusan soldiers were not afraid of the eclipse - history is silent). Associated with a lunar eclipse and a sad fate Kyiv prince Izyaslav, who died in battle a year after accession to the throne, which took place on February 12, 1161 - just on the day of the lunar eclipse ... however, at that time, alas, there was nothing unusual in such a fate for the prince - so Izyaslav's fate is different from the fate of many other Russian princes, perhaps by this very astronomical phenomenon. However, the eclipses of the Moon were still not feared in the same way as the solar ones (perhaps because we see the "concealment" of the Moon every month - although it looks different) - let's say, the priests of Babylon had a whole system: in what cases does a lunar eclipse portend something bad, and when - “the favor of the gods”).

Alas, practice shows that some of our contemporaries are not far from their distant ancestors: The internet is full of all sorts of "wise" advice about lunar eclipses: "don't look at the eclipse", "don't eat for three hours before it starts" and even "try to get rid of unwanted people in your life" (which is better to apply - poison, dagger or firearms - for some reason the astrologer does not specify). I don't know about the last recommendation - and the first one the scientists definitely disagree with! After all, lunar eclipses helped to learn something about our satellite - in particular, it was found that lunar soil does not conduct heat well (during eclipses, its temperature drops rapidly).

This year we have three lunar eclipses - though none of them will be total and only two of them will be visible in Europe. The first eclipse will occur on April 25, it will be private (the disk of the Moon will not be completely closed), the second - on October 18, penumbral (the Moon will not hide, but will only become less bright - see this naked eye almost impossible, it is fixed with devices). Another penumbral eclipse - May 25 - will be observed in Africa and America.

Solar eclipse- an astronomical phenomenon, which consists in the fact that the Moon closes (eclipses) the Sun in whole or in part from an observer on Earth. A solar eclipse is possible only on new moons, when the side of the Moon facing the Earth is not illuminated, and the Moon itself is not visible. Eclipses are possible only if the new moon occurs near one of the two lunar nodes(points of intersection visible orbits Moon and Sun), no more than about 12 degrees from one of them. The shadow of the moon on the earth's surface does not exceed 270 km in diameter, therefore solar eclipse observed only in a narrow band in the path of the shadow. Since the Moon revolves in an elliptical orbit, the distance between the Earth and the Moon at the time of an eclipse can be different, respectively, the diameter of the lunar shadow spot on the Earth's surface can vary widely from maximum to zero (when the top of the cone of the lunar shadow does not reach the Earth's surface). If the observer is in the shadow band, he sees a total solar eclipse in which the Moon completely hides the Sun, the sky darkens, and planets and bright stars can appear on it.

Around hidden by the moon the solar disk can be observed solar corona, which is not visible under the normal bright light of the Sun. When the eclipse is observed by a stationary ground observer, the total phase lasts no more than a few minutes. The minimum speed of the lunar shadow on the earth's surface is just over 1 km/s. During a total solar eclipse, astronauts in orbit can observe the moving shadow of the Moon on the Earth's surface.

Observers close to the total eclipse may see it as a partial solar eclipse. During a partial eclipse, the Moon passes across the disk of the Sun not exactly in the center, hiding only part of it. In this case, the sky darkens much weaker than during a total eclipse, the stars do not appear. A partial eclipse can be observed at a distance of about two thousand kilometers from the zone of total eclipse.

The totality of a solar eclipse is also expressed by the phase Ф. The maximum phase of a partial eclipse is usually expressed in hundredths of unity, where 1 is the total phase of the eclipse. The total phase can be greater than unity, for example 1.01, if the diameter of the visible lunar disk is greater than the diameter of the visible solar disk. Partial phases have a value less than 1. At the edge lunar penumbra phase is 0.

The moment when the leading / trailing edge of the Moon's disk touches the edge of the Sun is called touchdown. The first contact is the moment when the Moon enters the disk of the Sun (the beginning of the eclipse, its partial phase). The last touch (the fourth in the case of a total eclipse) is the last moment of the eclipse, when the moon leaves the disk of the Sun. In the event of a total eclipse, the second touch is the moment when the front of the Moon, having passed all over the Sun, begins to exit the disk. A total solar eclipse occurs between the second and third touches.

According to astronomical classification, if an eclipse at least somewhere on the surface of the Earth can be observed as total, it is called total. If the eclipse can only be observed as a partial eclipse (this happens when the cone of the moon's shadow passes near the earth's surface, but does not touch it), the eclipse is classified as partial. When an observer is in the shadow of the moon, he observes a total solar eclipse. When he is in the penumbra, he can observe a partial solar eclipse. In addition to total and partial solar eclipses, there are annular eclipses. An annular eclipse occurs when, at the time of the eclipse, the Moon is at a greater distance from the Earth than during a total eclipse, and the shadow cone passes over the earth's surface without reaching it. Visually, during an annular eclipse, the Moon passes over the disk of the Sun, but it turns out to be smaller than the Sun in diameter, and cannot completely hide it. In the maximum phase of the eclipse, the Sun is covered by the Moon, but a bright ring of the uncovered part of the solar disk is visible around the Moon. The sky during an annular eclipse remains bright, stars do not appear, it is impossible to observe the corona of the Sun. The same eclipse can be seen in different parts eclipse bands as total or annular. Such an eclipse is sometimes called a total annular (or hybrid) eclipse.

From 2 to 5 solar eclipses can occur on Earth per year, of which no more than two are total or annular. On average, 237 solar eclipses occur in a hundred years, of which 160 are partial, 63 are total, and 14 are annular. AT certain point Earth's surface eclipses in the major phase occur quite rarely, even more rarely observed total solar eclipses.

Moon eclipse

Moon eclipse An eclipse occurs when the Moon enters the cone of shadow cast by the Earth. The diameter of the spot of the Earth's shadow at a distance of 363,000 km (the minimum distance of the Moon from the Earth) is about 2.5 times the diameter of the Moon, so the entire Moon can be obscured. At each moment of the eclipse, the degree of coverage of the Moon's disk by the Earth's shadow is expressed by the phase of the eclipse F. The magnitude of the phase is determined by the distance 0 from the center of the Moon to the center of the shadow. AT astronomical calendars the values ​​Ф and 0 are given for different moments of the eclipse.

When the Moon during an eclipse completely enters the shadow of the Earth, they speak of a total lunar eclipse, when partially - a partial eclipse. A lunar eclipse can be observed on half of the Earth's territory (where the Moon is above the horizon at the time of the eclipse). The view of the shadowed Moon from any point of observation is negligibly little different from another point, and is the same. Maximum theoretically possible duration full phase lunar eclipse is 108 minutes; such were, for example, the lunar eclipses of August 13, 1859, July 16, 2000.

During an eclipse (even a total one), the Moon does not disappear completely, but becomes dark red. This fact is explained by the fact that the Moon, even in the phase of a total eclipse, continues to be illuminated. Sun rays, passing tangentially to the earth's surface, are scattered in the earth's atmosphere and, due to this scattering, partially reach the moon. Insofar as earth atmosphere it is most transparent for the rays of the red-orange part of the spectrum, it is these rays that reach the surface of the moon during an eclipse to a greater extent, which explains the color of the lunar disk. In fact, this is the same effect as the orange-red glow of the sky near the horizon (dawn) before sunrise or just after sunset. The Danjon scale is used to estimate the brightness of an eclipse.

Phases of a lunar eclipse

An observer on the Moon, at the time of a total (or partial, if he is on the shaded part of the Moon) lunar eclipse, sees a total solar eclipse (an eclipse of the Sun by the Earth).

If the Moon only partially falls into the total shadow of the Earth, a partial eclipse is observed. With it, part of the Moon is dark, and part, even in the maximum phase, remains in partial shade and is illuminated by the sun's rays.

Views of the Moon during a lunar eclipse

Around the cone of the Earth's shadow there is a penumbra - a region of space in which the Earth obscures the Sun only partially. If the Moon passes through the penumbra but does not enter the shadow, a penumbral eclipse occurs. With it, the brightness of the Moon decreases, but only slightly: such a decrease is almost imperceptible to the naked eye and is recorded only by instruments. Only when the Moon in a penumbral eclipse passes near the cone of total shadow, in a clear sky, one can notice a slight darkening from one edge of the lunar disk.

Every year there are at least two lunar eclipses, however, due to the mismatch of the lunar and earth orbit, their phases are different. Eclipses are repeated in the same order every 6585 days (or 18 years 11 days and 8 hours - a period called saros); knowing where and when a total lunar eclipse was observed, one can accurately determine the time of subsequent and previous eclipses that are clearly visible in this area. This cyclicity often helps to accurately date the events described in the historical annals.

A lunar eclipse occurs when the Moon (in the full moon phase) enters the cone of the shadow cast by the Earth. The diameter of the spot of the Earth's shadow at a distance of 363,000 km (the minimum distance of the Moon from the Earth) is about 2.5 times the diameter of the Moon, so the entire Moon can be obscured. A lunar eclipse can be observed on half of the Earth's territory (where the Moon is above the horizon at the time of the eclipse). The view of the shadowed Moon from any vantage point is the same. The maximum theoretically possible duration of the total phase of a lunar eclipse is 108 minutes; such were, for example, the lunar eclipses of August 13, 1859, July 16, 2000.

At each moment of the eclipse, the degree of coverage of the Moon's disk by the Earth's shadow is expressed by the phase of the eclipse F. The magnitude of the phase is determined by the distance 0 from the center of the Moon to the center of the shadow. In astronomical calendars, the values ​​\u200b\u200bof and 0 are given for different moments of the eclipse.

If the Moon falls into the total shadow of the Earth only partially, there is partial eclipse. With it, part of the Moon is dark, and part, even in the maximum phase, remains in partial shade and is illuminated by the sun's rays.

Around the cone of the Earth's shadow there is a penumbra - a region of space in which the Earth obscures the Sun only partially. If the Moon passes through the penumbra, but does not enter the shadow, penumbral eclipse. With it, the brightness of the Moon decreases, but only slightly: such a decrease is almost imperceptible to the naked eye and is recorded only by instruments. Only when the Moon in a penumbral eclipse passes near the cone of total shadow, in a clear sky, one can notice a slight darkening from one edge of the lunar disk.

An eclipsed moon flickers in the sky above the Monument to the Savior of the World in San Salvador, El Salvador, December 21, 2010.

(Jose CABEZAS/AFP/Getty Images)

During a total eclipse, the Moon takes on a reddish or brownish hue. The color of the eclipse depends on the condition of the upper layers of the earth's atmosphere, since only the light that has passed through it illuminates the moon during a total eclipse. Comparing pictures of total lunar eclipses different years, it is easy to see the difference in color. For example, the eclipse of July 6, 1982 was reddish, while the eclipse of January 20, 2000 was brown. The Moon acquires such colors during eclipses due to the fact that the earth's atmosphere scatters more red rays, so you can never observe, say, a blue or green lunar eclipse. But total eclipses differ not only in color, but also in brightness. Yes, exactly, brightness, and there is a special scale for determining the brightness of a total eclipse, called the Danjon scale (in honor of the French astronomer André Danjon, 1890-1967).

The gradation of the Danjon scale has 5 points. 0 - the eclipse is very dark (the Moon is barely visible in the sky), 1 - the eclipse is dark gray (details are noticeable on the Moon), 2 - the eclipse is gray with a brown tint, 3 - the light red-brown eclipse, 4 - the very light copper-red eclipse (The moon is clearly visible, and all the main details of the surface are distinguishable).

If the plane of the lunar orbit lay in the plane of the ecliptic, then lunar (as well as solar) eclipses would occur monthly. But most The moon spends time either above or below the plane of the earth's orbit due to the fact that the plane of the lunar orbit has a five-degree inclination to the plane of the earth's orbit. As a result, the natural satellite of the Earth falls into its shadow only twice a year, that is, at the time when the nodes of the lunar orbit (the points of its intersection with the ecliptic plane) are on the Sun-Earth line. Then a solar eclipse occurs on a new moon, and a lunar eclipse on a full moon.

Every year there are at least two lunar eclipses, however, due to the mismatch of the planes of the lunar and earth orbits, their phases differ. Eclipses repeat in the same order every 6585⅓ days (or 18 years 11 days and ~8 hours - a period called saros); knowing where and when a total lunar eclipse was observed, one can accurately determine the time of subsequent and previous eclipses that are clearly visible in this area. This cyclicity often helps to accurately date the events described in the historical annals. The history of lunar eclipses goes far into the past. The first total lunar eclipse is recorded in ancient Chinese chronicles. With the help of calculations, it was possible to calculate that it happened on January 29, 1136 BC. e. Three more total lunar eclipses are recorded in the Almagest by Claudius Ptolemy (March 19, 721 BC, March 8 and September 1, 720 BC). History often describes lunar eclipses, which helps a lot to establish the exact date one or another historical event. For example, the commander of the Athenian army Nikias was frightened by the beginning of a total lunar eclipse, a panic began in the army, which led to the death of the Athenians. Thanks to astronomical calculations, it was possible to establish that this happened on August 27, 413 BC. e.

In the Middle Ages, a total lunar eclipse did Christopher Columbus a great favor. His next expedition to the island of Jamaica was in a difficult situation, food and drinking water were running out, and people were threatened with starvation. Columbus's attempts to get food from the local Indians ended in vain. But Columbus knew that on March 1, 1504, a total lunar eclipse would occur, and in the evening he warned the leaders of the tribes living on the island that he would steal the Moon from them if they did not deliver food and water to the ship. The Indians just laughed and left. But, as soon as the eclipse began, the Indians were seized with indescribable horror. Food and water were immediately delivered, and the leaders on their knees begged Columbus to return the Moon to them. Columbus, of course, could not "refuse" this request, and soon the moon, to the delight of the Indians, shone again in the sky. As you can see, an ordinary astronomical phenomenon can be very useful, and knowledge of astronomy is simply necessary for travelers.

Observations of lunar eclipses can bring some scientific benefit, as they provide material for studying the structure of the earth's shadow and the state of the upper layers of the earth's atmosphere. Amateur observations of partial lunar eclipses come down to accurate recording of the moments of contact, photographing, sketching and describing changes in the brightness of the Moon and lunar objects in the eclipsed part of the Moon. The moments of contact of the lunar disk with the Earth's shadow and the descent from it are fixed (with the greatest possible accuracy) by the clock, adjusted according to the exact time signals. It is also necessary to note the contacts of the earth's shadow with large objects on the moon. Observations can be made with the naked eye, binoculars or a telescope. The accuracy of observations naturally increases when observing through a telescope. To register eclipse contacts, it is necessary to set the telescope to the maximum magnification for it and direct it to the corresponding points of contact of the Moon's disk with the Earth's shadow several minutes before the predicted moment. All entries are recorded in a notebook (an eclipse observation journal).

If an amateur astronomer has at his disposal a photoexposure meter (a device that measures the brightness of an object), then with its help you can plot the change in the brightness of the lunar disk during an eclipse. To do this, you need to set the exposure meter so that its sensitive element is directed exactly at the disk of the moon. The readings of the device are taken every 2-5 minutes, and are recorded in the table in three columns: the brightness measurement number, the time and the brightness of the moon. At the end of the eclipse, using the data in the table, it will be possible to display a graph of the change in the brightness of the Moon during this astronomical phenomenon. As a light meter, you can use any camera that has an automatic exposure system with an exposure scale.

Photographing the phenomenon can be done with any camera that has a removable lens. When shooting an eclipse, the lens is removed from the camera, and the body of the apparatus is attached to the eyepiece part of the telescope using an adapter. It will be shooting with ocular magnification. If the lens of your camera is non-removable, then you can simply attach the device to the eyepiece of the telescope, but the quality of such an image will be worse. If your camera or camcorder has the Zoom function, the need for additional magnifying tools, as a rule, disappears, because. the dimensions of the moon at the maximum magnification of such a camera are sufficient for filming.

However, the best quality images are obtained by photographing the Moon in the direct focus of the telescope. In such optical system a telescope lens automatically becomes a camera lens, only with a longer focal length.