When there is an eclipse. Why do solar and lunar eclipses occur?

An eclipse is an astronomical situation in which one celestial body completely blocks the light of another celestial body. The most famous are the eclipses of the Moon and the Sun. Eclipses are considered interesting natural phenomena, familiar to humanity since ancient times. They occur relatively often, but are not visible from every point on the earth. For this reason, eclipses seem to be a rare event to many. As everyone knows, planets and their satellites do not stand in one place. The Earth revolves around the Sun, and the Moon moves around the Earth. Periodically, moments arise when the Moon completely or partially covers the Sun. So why do solar and lunar eclipses occur?

Moon eclipse

During its full phase, the moon appears coppery red, especially as it approaches the center of the shadow region. This shade is due to the fact that the rays of the sun, tangent to the surface of the earth, passing through the atmosphere, are scattered and fall into the shadow of the Earth through a thick layer of air. This works best with rays of red and orange shades. Therefore, only they paint the lunar disk this color, based on the state of the earth’s atmosphere.

Eclipse of the sun

A solar eclipse is the lunar shadow on the surface of the Earth. The diameter of the shadow spot is about two hundred kilometers, which is several times smaller than the earth. For this reason, an eclipse of the sun can only be seen in a narrow strip along the path of the moon's shadow. An eclipse of the Sun occurs when the Moon comes between the observer and the Sun, blocking it.

Since the Moon on the eve of an eclipse is turned towards us with the side that does not receive light, a new moon always occurs on the eve of an eclipse of the Sun. Simply put, the Moon becomes invisible. It seems that the Sun is covered by a black disk.

Why do solar and lunar eclipses occur?

The phenomena of solar and lunar eclipses are clearly observed through. Observers were able to achieve great achievements by confirming the effect of gravity of large space objects on light rays.

Astronomical knowledge is an interesting part of the general knowledge required for a person to understand what is happening in the environment. We direct our gaze to the sky whenever dreams take over our minds. Sometimes certain phenomena strike a person to the core. We will talk about these in our article, namely what a lunar and solar eclipse is.

Although today the disappearance or partial concealment of luminaries from our eyes does not cause such superstitious fear as it did among our ancestors, a special aura of mystery of these processes remains. Nowadays, science has facts that can be used to explain this or that phenomenon in a simple and accessible way. We will try to do this in today’s article.

and how does it happen?

A solar eclipse is one that occurs as a result of the Earth's satellite eclipsing the entire solar surface or part of it facing observers located on the ground. However, it is possible to see it only during the new moon, when the part of the Moon facing the planet is not completely illuminated, that is, it becomes invisible to the naked eye. We understand what an eclipse is, and now we will find out how it happens.

An eclipse occurs when the Moon is not illuminated by the Sun from the side visible on Earth. This is possible only in the growing phase, when it is near one of the two lunar nodes (by the way, the lunar node is the point of intersecting lines of two orbits, solar and lunar). Moreover, the lunar shadow on the planet has a diameter of no more than 270 kilometers. Therefore, it is possible to observe an eclipse only at the location of the passing shadow strip. In turn, the Moon, rotating in orbit, maintains a certain distance between it and the Earth, which at the moment of an eclipse can be completely different.

When do we observe a total solar eclipse?

You've probably heard about the concept of a total eclipse. Here we will once again clearly outline what a total solar eclipse is and what conditions are needed for it.

The shadow of the Moon falling on the Earth is a certain spot of a certain diameter with a possible change in size. As we have already said, the diameter of the shadow does not exceed 270 kilometers, while the minimum figure is approaching zero. If at this moment the observer of the eclipse finds himself in a dark stripe, he has a unique opportunity to witness the complete disappearance of the Sun. At the same time, the sky becomes dark, with the outlines of stars and even planets. And around the previously hidden solar disk, the outline of a corona appears, which is impossible to see in normal times. A total eclipse lasts no more than a few minutes.

The photographs of this unique phenomenon presented in the article will help you see and understand what a solar eclipse is. If you decide to observe this phenomenon live, you must follow safety precautions regarding vision.

With this, we finished the information block in which we learned what a solar eclipse is and what conditions are necessary to see it. Next we have to get acquainted with the lunar eclipse, or, as it sounds in English, lunar eclipse.

What is a lunar eclipse and how does it happen?

A lunar eclipse is a cosmic phenomenon that occurs when the Moon falls into the shadow of the Earth. At the same time, as with the Sun, events can have several development options.

Depending on certain factors, a lunar eclipse can be total or partial. Logically, we can well assume what this or that term that characterizes a particular eclipse means. Let's find out what a total lunar eclipse is.

How and when does a planet's satellite become invisible?

Such an eclipse of the Moon is usually visible where it is located above the horizon at the appropriate moment. The satellite appears in the shadow of the Earth, but at the same time a total eclipse is not able to hide the Moon completely. In this case, it is only slightly shaded, acquiring a dark, reddish tint. This happens because, even being completely in the shadow, the lunar disk does not cease to be illuminated by the sun's rays passing through the earth's atmosphere.

Our knowledge has expanded with facts about the lunar eclipse. However, these are not all the possible options for the eclipse of a satellite by the earth's shadow. We'll talk about the rest further.

Partial lunar eclipse

As in the case of the Sun, the darkening of the visible surface of the Moon is often incomplete. We can observe a partial eclipse when only a certain part of the Moon is in the shadow of the Earth. This means that when part of the satellite is eclipsed, that is, obscured by our planet, then its second part continues to be illuminated by the Sun and remains clearly visible to us.

A penumbral eclipse will seem much more interesting and unusual, differing from others in astronomical processes. We will talk further about what a penumbral lunar eclipse is.

Unique penumbral lunar eclipse

This type of eclipse of the Earth's satellite occurs a little differently than a partial eclipse. It is easy to find out from open sources or from your own experience that there are areas on the surface of the Earth where the sun's rays are not completely obscured, and therefore cannot be a shadow. But there is no direct sunlight either. This is the penumbra region. And when the Moon, which finds itself in this very place, finds itself in the penumbra of the Earth, we can observe a penumbral eclipse.

When entering the penumbral region, the lunar disk changes its brightness, becoming slightly darker. True, such a phenomenon is almost impossible to notice and recognize with the naked eye. For this you will need special devices. It is also interesting that at one edge of the Moon's disk the darkening may be more noticeable.

So we have finished the second main block of our article. Now we can easily explain ourselves what a lunar eclipse is and how it happens. But the interesting facts about solar and lunar eclipses don't end there. Let's continue the topic by answering some questions related to these amazing phenomena.

Which eclipses occur more often?

After everything that we have learned from the previous parts of the article, the question naturally arises: which of the eclipses do we have a better chance of seeing in our lives? Let's also say a few words about this.

It’s incredible, but true: the number of eclipses of the Sun is greater, even though the Moon is smaller in size than. After all, knowing what an eclipse is and why it occurs, one might think that the shadow of a larger object is more likely to block a smaller one than vice versa. Based on this logic, the size of the Earth allows us to hide the lunar disk in no time.
Nevertheless, it is precisely solar eclipses that happen more often on the planet. According to statistics from astronomers and observers, for every seven eclipses there are only three lunar and solar eclipses, respectively, four.

The reason for the amazing statistics

The disks of the celestial bodies closest to us, the Sun and the Moon, are almost identical in diameter in the sky. It is for this reason that solar eclipses can occur.

Typically, solar eclipses occur during the new moon period, that is, when the Moon approaches its orbital nodes. And since it is not perfectly round, and the nodes of the orbit move along the ecliptic, during favorable periods the disk of the Moon on the celestial sphere can be either larger, smaller, or even equal to the solar disk.

In this case, the first case contributes to a total eclipse. The decisive factor is the angularity. At its maximum size, the eclipse can last up to seven and a half minutes. The second case involves complete shading for just seconds. In the third case, when the moon's disk is smaller than the sun's, a very beautiful eclipse occurs - an annular one. Around the dark disk of the Moon we see a shining ring - the edges of the solar disk. This eclipse lasts 12 minutes.

Thus, we have supplemented our knowledge of what a solar eclipse is and how it occurs with new details worthy of amateur researchers.

Eclipse factor: location of luminaries

An equally important reason for an eclipse is the uniform distribution of heavenly bodies. The Moon's shadow may or may not fall on the Earth. And sometimes it happens that only the penumbra of an eclipse falls on the Earth. In this case, you can observe a partial, that is, incomplete eclipse of the Sun, which we already talked about when we talked about what a solar eclipse is.

If a lunar eclipse can be observed from the entire night surface of the planet, from which the circumference of the lunar disk is visible, then a solar eclipse can only be observed when you are in a narrow strip with an average width of 40-100 kilometers.

How often can you see eclipses?

Now that we know what an eclipse is and why some happen more than others, one more exciting question remains: how often can these amazing phenomena be observed? After all, in our lives, each of us has heard only one piece of news about an eclipse, a maximum of two, some - not a single one...

Despite the fact that a solar eclipse occurs more often than a lunar eclipse, it can still be seen in the same area (remember the strip with an average width of 40-100 kilometers) only once every 300 years. But a person can observe a total lunar eclipse several times in his life, but only if the observer has not changed his place of residence throughout his life. Although today, knowing about the blackout, you can get anywhere and by any means of transport. Those who know what a lunar eclipse is will probably not stop walking a hundred or two kilometers for the incredible spectacle. Today there are no problems with this. And if you suddenly receive information about the next eclipse in some place, do not be lazy and spare no expense in order to get to the place of maximum visibility at the moment when you can observe the eclipse taking place. Believe me, no distance can compare with the impressions received.

Nearest visible eclipses

You can learn about the frequency and schedule of eclipses from the astronomical calendar. In addition, significant events such as a total eclipse will definitely be discussed in the media. The calendar says that the next solar eclipse visible in the Russian capital will take place on October 16, 2126. Let us also recall that the last eclipse in this territory could be observed more than a hundred years ago - in 1887. So Moscow residents won’t have to watch a solar eclipse for many years. The only opportunity to see this amazing phenomenon is to go to Siberia, the Far East. There you can observe a change in the brightness of the Sun: it will only darken a little.

Conclusion

With our astronomical article, we tried to explain clearly and briefly what an eclipse of the Sun and Moon is, how these phenomena occur, and how often they can be seen. The conclusion of our research in this area: eclipses of different celestial bodies occur according to different principles and have their own characteristics. But understanding some of the details necessary for the average person to fully understand the environment is very important.

Nowadays, thanks to developed science and technology, the temporarily extinguished star is no longer frightening, but remains just as alluringly mysterious. Today we know what a lunar and solar eclipse are and what they bring to us. Let the interest in them now be purely cognitive as a rare outlandish phenomenon. Finally, we wish you to see at least one eclipse with your own eyes!

Every person has observed a solar eclipse at least once in their life or at least heard about it. This phenomenon has long attracted attention - at all times it was considered a harbinger of misfortune, some peoples perceived it as God's wrath. It really looks a little creepy - the solar disk is completely or partially covered by a black spot, the sky darkens, and sometimes you can even make out stars on it. This phenomenon causes fear in animals and birds - they gather in flocks and seek shelter. Why does a solar eclipse occur?

The essence of this phenomenon is quite simple - the Moon and the Sun line up in one line, and thus our earthly satellite blocks the star. The Moon is much smaller than the Sun, but because it is much closer to the Earth, a person observing a solar eclipse will see it covering the entire solar disk.

A solar eclipse can be total or partial, depending on how much the Moon covers our star.

On average, 2 to 5 eclipses occur on Earth annually.

Sometimes you can observe a rare astronomical phenomenon - the so-called circular eclipse. At the same time, the Moon appears smaller than the Sun, and covers only its middle part, exposing the solar atmosphere. This type of eclipse is extremely valuable for researchers of the processes occurring on our star. It makes it possible to better view the upper layers of the Sun. In particular, such eclipses have greatly helped in the study of the solar corona. It happens that the Moon appears larger than the Sun, then the disk is so blocked that even the rays emanating from it are not visible from the Earth. This variety of eclipses is explained by the fact that the lunar orbit has an elongated ellipsoidal shape, so at different times of the year it is further or closer from the Earth.

Scientists have long found the answer to the question of how and why a solar eclipse occurs., saving humanity from prejudices towards this phenomenon. Moreover, it can now be predicted. This made it possible to take a fresh look at many historical events. Thus, chroniclers, describing battles and other important events, often mentioned that a solar eclipse occurred on that day, without giving the exact date. Now, thanks to the calculations of modern scientists, these dates have been restored.

What is a Solar Eclipse?

A solar eclipse is a natural phenomenon that occurs on Earth when the Moon moves in its orbit between the Earth and the Sun. This occurs on a new moon when the sun and moon are in conjunction with each other. If the Moon were just a little closer to the earth, and its orbit was in the same plane and circular, then we would see eclipses every month. The Moon's orbit is elliptical and tilted relative to the Earth's orbit, so we can only see up to 5 eclipses per year. Depending on the geometry of the Sun, Moon and Earth, the Sun may be completely blocked (obscured), or it may be partially blocked.

During an eclipse, the Moon's shadow (which is divided into two parts: dark umber and light penumbra) moves across the earth's surface. Safety note: Never look directly at the sun during a total solar eclipse. The bright light of the sun can damage your eyes very quickly.

Types of Solar Eclipse

TOTAL SOLAR ECLIPSE

A total solar eclipse occurs when the Moon completely covers the solar disk. During a total solar eclipse, the narrowest part of the path where the sun is completely blocked and the moon casts its dark shadow (called the total umbra) is called the “zone of totality.”

Observers see this path as a darkened sun (often described as a “hole in the sky”) with the ghostly glow of the solar corona traveling into space. The phenomenon is called “Bailey's rosary” and often appears when sunlight filters through valleys on the surface of the Moon. If the sun is active, observers may also see solar prominences, loops, and flares during the eclipse. A total solar eclipse is the only time when it is safe to look directly at the sun. All other solar observations (even partial phases) require special solar filters to avoid damaging your eyes.

A total solar eclipse is not always visible from Earth. In the past, the Moon was too close to the earth and during an eclipse it completely obscured the disk of the Sun. Over time, the lunar orbit has changed by a little more than 2 cm per year and in the current era, the situation is almost ideal. However, the Moon's orbit will continue to expand, and perhaps in 600 million years, total solar eclipses will no longer occur. Instead, future observers will only see partial and annular eclipses.

RING-SHAPED SOLAR ECLIPSE

When the Moon is further in its orbit than usual, it cannot completely cover the disk of the Sun. During such an event, a bright ring of sunlight shines around the moon. This type of eclipse is called an annular eclipse." It comes from the Latin word “annulus”, which means “ring”.

The "ring" period during such an eclipse can last from 5 or 6 minutes to 12 minutes. However, although the Sun is mostly covered by the Moon, when sunlight is bright enough, a ring-shaped glow occurs during which observers will never be able to look at the Sun directly. This event requires eye protection throughout the eclipse.

PARTIAL SOLAR ECLIPSE

A partial solar eclipse occurs when the Earth moves across the lunar penumbra as the moon moves between the Earth and the sun. The Moon does not block the entire solar disk, as seen from Earth. Depending on your location during a partial eclipse, you may see anything from a small piece of the Sun to almost a total eclipse.

To view any eclipse, it is safe to use a filter, or use an indirect viewing method, such as projecting the rays through a telescope onto a white sheet of paper or cardboard. Never look at the sun through a telescope unless it has an appropriate filter. Blindness and severe eye damage can be caused by improper observation techniques.

Facts About Solar EclipsesDepending on the geometry of the Sun, Moon and Earth, there can be from 2 to 5 solar eclipses per year. The totality occurs when the Moon completely covers the sun, so that only the solar corona is visible. A total solar eclipse can occur once every 1- 2 years. This makes them very rare events. If you lived at the North or South Pole, you would only see a partial solar eclipse. People in other parts of the world may experience partial, total, annular and hybrid eclipses. The longest total solar eclipse can last 7.5 minutes. The eclipse path is typically about 100 miles in diameter and can cast a shadow over an area of ​​Earth's surface of about 10,000 miles in length. Almost identical eclipses occur every 18 years and 11 days. This period of 223 synodic months is called saros. During a total solar eclipse, the air temperature can quickly change, immediately becoming colder and the immediate surroundings becoming dark. At the moment of a total solar eclipse, the planets in the sky can be seen as points of light.

It is unlikely that any eyewitness will remain indifferent to such a remarkable phenomenon associated with the Moon as a total solar eclipse. For thousands of years, the black circle engulfing the Sun in broad daylight has inspired people with superstitious fear and awe. To understand the cause of solar eclipses, ancient sky watchers spent centuries painstakingly counting all eclipses, trying to find a pattern and determine the sequence of eclipses. In the end, it turned out that solar eclipses are possible only at the time of new moon, when the Moon passes between the Earth and the Sun.

The Moon, illuminated by the Sun, blocks the path of the sun's rays and casts into space a converging cone of shadow and a diverging cone of penumbra surrounding it, which, under certain circumstances, fall on small areas of the Earth's surface, where observers at that moment see the Sun being covered by a black disk.

Geometry of the onset of a solar eclipse

In the earth's sky, the diameters of the Moon and the Sun almost coincide, which allows the Moon to completely eclipse our daylight star in the sky. This is despite the fact that the diameter of the Sun is almost 400 times the diameter of the Moon. And all because the Sun is about 400 times farther from the Earth than the Moon. This exceptional coincidence, not repeated on any other planet, allows us to observe solar eclipses.

Solar eclipses do not occur at all new moons. The reason for this is that the Moon's path in the sky is tilted about 5° to the Sun's path, the ecliptic. Therefore, eclipses occur only near the intersection points (“nodes”) of their trajectories, where the luminaries are sufficiently close. Depending on the distance to the Moon and the Sun, the size of this zone changes. For solar eclipses, its boundaries are 16°-18° away from the node in each direction. The closer to the node the eclipse occurs, the longer it will last. The longest central eclipses occur at the nodes themselves; in this case, the strip of the main phase passes through the tropical latitudes of the Earth.

Nodes of the lunar orbit and eclipse zones

During new moons that occur far from the lunar nodes, solar eclipses are impossible - the Moon passes above or below the Sun in the sky. Only during new moons near the lunar nodes are eclipses possible.

Sliding along the earth's surface, the end of the moon's shadow draws on it " solar eclipse visibility band". The diameter of the lunar shadow on the earth's surface during a total solar eclipse does not exceed 270 km (most often from 40 to 100 km), and the diameter of the lunar penumbra is close to 6750 km (with an annular eclipse, the width of the central stripe can reach 380 km, and the diameter lunar penumbra - 7340 km). At the same time, the lunar shadow and penumbra on the earth's surface have the form of oval spots, the shape of which depends on the position of the Sun and Moon above the horizon. The lower their height, the more gently the axis of both cones is directed towards the earth's surface, and the more spots of shadow and penumbra are elongated.

The path of the moon's shadow across the earth's surface in 2017

The lunar shadow runs along the Earth from 6,000 to 12,000 km. A solar eclipse begins in the western regions at sunrise and ends in the east at sunset. The total duration of all phases of a solar eclipse on Earth can reach six hours.

TYPES OF SOLAR ECLIPSE

There may be an eclipse complete, ring-shaped And private. The degree to which the Sun is covered by the Moon is called the eclipse phase. It is defined as the ratio of the closed part of the diameter of the solar disk to its entire diameter.

Phase (magnitude) of solar eclipses

Since the Moon’s orbit is not circular, but elliptical, at moments favorable for the onset of eclipses, the lunar disk may appear slightly larger or smaller than the solar one. In the first case, a total eclipse occurs. In the second case, an annular eclipse occurs: a shining ring of the Sun's surface is visible around the dark disk of the Moon.

Total solar eclipse - a phenomenon when the Moon completely covers the Sun in the Earth's sky. If the observer is in the central band of the shadow, he sees a total solar eclipse, in which the Moon completely hides the Sun, the solar corona (the outer layers of the Sun's atmosphere that are not visible in normal light of the Sun) is revealed, the sky darkens, and planets and planets may appear on it. bright stars. For example, Venus and Jupiter will be the easiest to spot due to their brightness.

Diagram of a total solar eclipse

Changes in the appearance of the sky during a total solar eclipse

Observers on either side of the central band of totality can only see a partial solar eclipse. The Moon passes across the disk of the Sun not exactly in the center, hiding only part of it. At the same time, the sky does not darken, the stars do not appear.

At annular eclipse The Moon passes across the disk of the Sun, but turns out to be smaller in diameter than the Sun, and cannot hide it completely. This happens because the distance of the Moon from the Earth varies from 405 thousand km (apogee) to 363 thousand km (perigee), and the length of the full shadow cone from the Moon is 374 thousand km, so the top of the lunar shadow cone sometimes does not reach the earth’s surface . In this case, for an observer below the apex of the axis of the lunar shadow cone, the solar eclipse will be annular.

Diagram of an annular solar eclipse

Partial solar eclipse is an eclipse in which only the lunar penumbra crosses the earth's surface. This occurs when the Moon's shadow passes above or below the Earth's polar regions, leaving only the lunar penumbra on our planet.

Diagram of a partial solar eclipse (without the central eclipse band)

During partial eclipses, the weakening of sunlight is not noticeable (with the exception of eclipses with a large phase), and therefore the phases of the eclipse can only be observed through a dark filter.

On the use of protective filters when observing solar eclipses in the material:

DURATION AND FREQUENCY OF SOLAR ECLIPSE ON EARTH

The maximum duration of a total solar eclipse is 7.5 minutes. This is possible from the end of June to mid-July, when the diameter of the solar disk in the sky is minimal (the Sun passes the aphelion of its orbit), and the Moon is at its smallest distance from the Earth (perihelion). The previous long solar eclipse lasted 7 minutes and 7 seconds (Southeast Asia, June 20, 1955). And the shortest solar eclipse (1 second) occurred on October 3, 1986 (North Atlantic Ocean). The nearest eclipse, lasting 7 minutes 29 seconds, will occur on July 16, 2186.

The longest duration of the annular phase cannot exceed 12.3 minutes, and the duration of a partial eclipse can reach approximately 3.5 hours. The vast majority of eclipses last up to 2.5 hours (partial phases), and their total or annular phase usually does not exceed 2-3 minutes.

Every year there are two eras of eclipses, the interval between which is 177 - 178 days. One eclipse zone occupies about 34°; the Sun spends about 34 days in each zone. And the period between new moons is 29.5 days (synodic month), which means the Moon must necessarily pass through the eclipse zone while the Sun is there, and can visit it twice during this period. Therefore, with each passage of the Sun through the eclipse zone (once every six months), one eclipse should occur, but two can occur. Thus, from 2 to 5 solar eclipses can occur on Earth per year. Over the course of six months (about 183 days), eclipse epochs shift five days ahead, to earlier calendar dates, and gradually move to different seasons of the year - from summer and winter to spring and autumn, again to winter and summer, etc.

Five solar eclipses per year are possible, if the first pair of partial solar eclipses in one zone occurs in early January and February, then the next pair of partial eclipses in another zone may occur at the very beginning of July and August, and from the next probable pair of partial eclipses only one is possible at the very end of December, and the second will occur in January of the next calendar year. Thus, the largest number of solar eclipses in one calendar year does not exceed five, and all of them are necessarily partial with small phases.

Central visibility bands of total and annular eclipses from 1981 to 2100

Most often, there are 2-3 solar eclipses annually, and one of them is often total or annular. Four partial eclipses last occurred in 2000 and 2011. The next years when four partial eclipses are expected are 2029 and 2047. The last time there were five partial solar eclipses (all of which are necessarily partial with small phases) in one calendar year was in 1935. The next time such a phenomenon is expected is in 2206.

The pattern of recurrence of solar eclipses is very complex. Each solar eclipse repeats itself over a period of time of 6585.3 days or 18 years 11.3 days (or 10.3 days if the period contains five leap years), called a saros. During Saros, on average, 42-43 solar eclipses occur, of which 14 are total, 13-14 annular and 15 partial. However, after the end of Saros, each eclipse is repeated under different conditions, since Saros does not contain a whole number of days, and for an excess of about 0.3 days (over 6585 days), the Earth will rotate around its axis by approximately 120° and therefore the lunar shadow will run across the Earth’s surface the same 120° to the west than 18 years ago, and the Sun and Moon will be at slightly different distances from the lunar node. On average, every hundred years there are 237 solar eclipses on Earth, of which 160 are partial, 63 are total, 14 are annular.

In one locality, total solar eclipses occur on average once every 360 years, with rare exceptions. Partial solar eclipses occur in each area much more often - on average every 2-3 years, but since during solar eclipses with a small phase the sunlight almost does not weaken, they are not of great interest and usually go unnoticed.

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