The most significant astronomical phenomena that can be seen on planet Earth

Solar eclipse- an astronomical phenomenon, which consists in the fact that the Moon completely or partially covers the Sun from an observer on Earth. In other words, in its movement along with the Earth around the Sun, the Moon often obscures the stars of the constellations along which the lunar path passes. Periodically, the Moon partially or completely obscures the Sun - solar eclipses occur. A total solar eclipse occurs about once every one and a half years. But the area where it can be observed from Earth is very small. At the same point, the moon's shadow can pass only once every 200-300 years, which means that it is unlikely that you will be able to see this breathtaking sight in a lifetime.

Moon eclipse

Moon eclipse- An eclipse that occurs when the Moon enters the cone of shadow cast by the Earth. 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. The frequency of lunar eclipses for any particular place on Earth is higher than the frequency of solar eclipses only because they are visible from the entire night hemisphere of the Earth. In this case, the duration of the total phase of a solar eclipse on the Moon can reach 2.8 hours.

Northern lights

Polar Lights (Northern Lights) - the glow of the upper layers of the atmospheres of planets with a magnetosphere due to their interaction with charged particles of the solar wind. The answer to the question, what is it, was the first to find Mikhail Lomonosov. After conducting countless experiments, he suggested the electrical nature of this phenomenon. Scientists who continued to study this phenomenon, on the basis of experiments, confirmed the correctness of his hypothesis. When viewed from the surface of the Earth, the aurora appears as a general rapidly changing glow of the sky or moving rays, stripes, crowns, "curtains". The duration of auroras ranges from tens of minutes to several days.

Parade of planets

Parade of planets- an astronomical phenomenon in which a certain number of planets solar system turns out to be on one side of the Sun in a small sector. Moreover, they are more or less close to each other on the celestial sphere.

• A small parade is an astronomical phenomenon during which four planets are on the same side of the Sun in a small sector. These planets include: Venus, Mars, Jupiter, Saturn, Mercury.
• The Grand Parade is an astronomical phenomenon during which six planets appear on the same side of the Sun in a small sector. These include: Earth, Venus, Jupiter, Mars, Saturn, Uranus.

A mini parade of planets involving four planets occurs more often, and mini parades of planets involving three planets can be observed annually (or even twice a year), but their visibility conditions are not the same for different latitudes of the Earth.

Meteor Rain

Meteor Rain(iron rain, stone rain, fire rain) - a multiple fall of meteorites due to the destruction of a large meteorite in the process of falling to Earth. When a single meteorite falls, a crater is formed. When a meteor shower falls, a crater field is formed. Concepts should be separated meteor shower and meteor Rain. A meteor shower consists of meteors that burn up in the atmosphere and do not reach the ground, while a meteor shower consists of meteorites that fall to the ground. Previously, they did not distinguish the first from the second, and both of these phenomena were called "rain of fire."

Earth in the Universe

All observation points for water quality of reservoirs and streams are divided into 4 categories, determined by the frequency and detail of observation programs. The purpose and location of control points are determined by the rules for monitoring the quality of water in reservoirs and streams.

· in areas of cities with a population of over 1 million inhabitants;

· in places of spawning and wintering of especially valuable species of commercial fishes;

· in areas of repeated accidental discharges of pollutants;

in areas of organized discharge Wastewater resulting in high water pollution.

· in areas of cities with a population of 0.5 to 1 million inhabitants;

· in places of spawning and wintering of valuable species of commercial fishes (organisms);

· in pre-dam sections of rivers important for fisheries;

· in places of organized discharge of drainage wastewater from irrigated areas and industrial wastewater;

when crossing rivers state border;

in areas with moderate water pollution.

· in areas of cities with a population of less than 0.5 million inhabitants;

on the closing sections of large and medium-sized rivers;

· in the mouths of polluted tributaries of large rivers and reservoirs;

· in areas of organized wastewater discharge, resulting in low water pollution.

in uncontaminated areas of reservoirs and watercourses,

on reservoirs and streams located in the territories state reserves and national parks.

Water quality monitoring is carried out according to certain types of programs, which are selected depending on the category of the control point. The frequency of monitoring by hydrobiological and hydrochemical indicators is set in accordance with the category of the observation point. When choosing a control program, the intended use of a reservoir or watercourse, the composition of wastewater discharged, and the requirements of consumers of information are taken into account.

Parameters to be defined compulsory program quality observations surface water according to hydrochemical and hydrological indicators are given in Table. Table

Parameters, the determination of which is provided for by the mandatory observation program

Options	Units
Water consumption (on watercourses)
Water flow rate (on watercourses)
Water level (on reservoirs)
visual observations
Temperature
Chroma
Transparency
Oxygen
Carbon dioxide
suspended solids
Hydrogen indicator(pH)
Redox potential (Eh)
chlorides (Cl-)
sulfates (SO42-)
Bicarbonates (HCO3-)
Calcium (Ca2+)
Magnesium (Mg2+)
Sodium (Na+)
Potassium (K+)
Sum of ions (i)
ammonium nitrogen (NH4+)
nitrite nitrogen (NO2-)
Nitrate nitrogen (NO3-)
mineral phosphorus (PO43-)
Iron total
Oil products
Phenols (volatile)
Pesticides
Heavy metals

Observations according to the mandatory program on watercourses are carried out, as a rule, 7 times a year during the main phases of the water regime: during floods - at rise, peak and decline; during the summer low water - at the lowest flow rate and during the passage of a rain flood; in autumn - before freezing; during winter low water.

In reservoirs, water quality is examined in the following hydrological situations: in winter, at the lowest level and the greatest thickness of ice; at the beginning of the spring filling of the reservoir; during the period of maximum filling; during the summer-autumn period at the lowest water level.

abbreviated program observations of the quality of surface waters according to hydrological and hydrochemical indicators are divided into three types:

· First program provides for the determination of water flow (in watercourses), water level (in reservoirs), temperature, concentration of dissolved oxygen, electrical conductivity, visual observations.

· Second program provides for the determination of water flow (on watercourses), water level (on reservoirs), temperature, pH, specific electrical conductivity, concentration of suspended solids, COD, BOD5, concentrations of 2–3 pollutants, the main ones for water at a given control point, visual observations.

· Third program provides for the determination of water flow, flow velocity (on watercourses), water level (on water bodies), temperature, pH, concentrations of suspended solids, concentrations of dissolved oxygen, BOD5, concentrations of all water pollutants in a given control point, visual observations.

Hydrochemical indicators of the quality of natural waters at control points are compared with established water quality standards.

Programs and periodicity of observations on hydrochemical indicators for points of various categories are given in Table.

Programs and frequency of observations for sites of various categories

Frequency of control
Daily	Abbreviated Program 1	visual observations
Every ten days	Abbreviated Program 2	Abbreviated Program 1
Monthly	Abbreviated Program 3
In the main phases of the water regime	Required Program

The introduction of hydrobiological methods into the monitoring system for water quality makes it possible to directly determine the composition and structure of hydrobiont communities.

Full program monitoring the quality of surface waters hydrobiological indicators provides:

· study phytoplankton– total number of cells, number of species, total biomass, number of main groups, biomass of main groups, number of species in a group, mass species

· study zooplankton– total number of organisms, total number of species, total biomass, number of main groups, biomass of main groups, number of species in a group, mass species and species-indicators of saprobity;

· study zoobenthos– total abundance, total biomass, total number of species, number of groups according to standard development, number of species in a group, number of main groups, biomass of main groups, mass species and saprobity indicator species;

· study periphyton - total number of species, mass species, frequency of occurrence, saprobity;

· definition microbiological indicators - the total number of bacteria, the number of saprophytic bacteria, the ratio of the total number of bacteria to the number of saprophytic bacteria;

· the study photosynthesis phytoplankton and destruction organic matter, determination of the ratio of the intensity of photosynthesis to the destruction of organic matter, the content of chlorophyll;

· study macrophytes– projective cover of the experimental site, nature of vegetation distribution, total number of species, prevailing species (name, projective cover, phenophase, anomalous features).

Abbreviated Program observations of the quality of surface waters in terms of hydrobiological indicators provides for the study of:

· phytoplankton- the total number of cells, the total number of species, mass species and species-indicators of saprobity;

· zooplankton– total number of organisms, total number of species, mass species and species-indicators of saprobity;

· zoobenthos- the total number of groups according to the standard development, the number of species in the group, the number of main groups, mass species and species-indicators of saprobity;

· periphyton - total number of species, mass species, saprobity, frequency of occurrence.

Programs and periodicity of observations according to hydrobiological indicators for stations of various categories are given in Table.

Frequency of observations on hydrobiological indicators and types of programs

Periodicity of observations
Monthly	Abbreviated Program	Abbreviated Program	Reduced program (control during the growing season)
Quarterly	Full program

Observations of lunar eclipses

Like solar eclipses, lunar eclipses occur relatively rarely, and at the same time, each eclipse is characterized by its own characteristics. Observations of lunar eclipses make it possible to refine the orbit of the moon and provide information about the upper layers of the earth's atmosphere.

Observation program lunar eclipse may consist of the following elements: determination of the brightness of the shadowed parts of the lunar disk from the visibility of the details of the lunar surface when observed through 6x recognized binoculars or a telescope with low magnification; visual estimates of the brightness of the Moon and its color both with the naked eye and with binoculars (telescope); observations through a telescope with a lens diameter of at least 10 cm at 90x magnification throughout the eclipse of the craters Herodotus, Aristarchus, Grimaldi, Atlas and Riccioli, in the area of ​​which color and light phenomena can occur; registration with a telescope of the moments of covering by the earth's shadow of some formations on the lunar surface (the list of these objects is given in the book "Astronomical calendar. Permanent part"); determination using a photometer of the brightness of the surface of the moon at various phases of the eclipse.

Observations artificial satellites Earth and the influence of the Sun on life on Earth

When observing artificial satellites of the Earth, the path of the satellite's movement is noted on star map and the time of its passage is about noticeable bright stars. Time must be recorded to the nearest 0.2 s using a stopwatch. Bright satellites can be photographed.

Solar radiation - electromagnetic and corpuscular - is the powerful factor that plays a huge role in the life of the Earth as a planet. Sunlight and solar heat created the conditions for the formation of the biosphere and continue to support its existence. With amazing sensitivity, everything earthly - both living and non-living - reacts to changes in solar radiation, to its unique and complex rhythm. So it was, so it is, and so it will be until a person is able to make his own adjustments to the solar-terrestrial relations.

Let's compare the Sun with... a string. This will make it possible to understand the Physical essence of the rhythm of the Sun and the reflection of this rhythm and the history of the Earth.

You pulled back the middle of the string and released it. The vibrations of the string, amplified by the resonator (the soundboard of the instrument), gave rise to sound. The composition of this sound is complex: after all, as you know, not only the entire string as a whole vibrates, but also its parts at the same time. The string as a whole generates the fundamental tone. The halves of the string, vibrating faster, emit a higher, but less powerful sound - the so-called first overtone. The halves of the halves, that is, the quarters of the string, in turn give rise to an even higher and even weaker sound - the second overtone, and so on. The full sound of a string is made up of the fundamental tone and overtones, which in different musical instruments give the sound a different timbre, shade.

According to the hypothesis of the famous Soviet astrophysicist Professor M.S. Eigenson, once, billions of years ago, in the depths of the Sun, the same proton-proton cycle of nuclear reactions began to operate, which supports the radiation of the Sun in the modern era; the transition to this chicle was probably accompanied by some kind of internal restructuring of the Sun. From the previous state of equilibrium, it abruptly passed to a new one. And with this jump, the Sun sounded like a string. The word "sounded" should be lowered, of course, in the sense that in the Sun, in its gigantic mass, some kind of rhythmic oscillatory processes arose. Cyclic transitions from activity to passivity and back began. Perhaps these fluctuations that have survived to this day are expressed in cycles of solar activity.

Outwardly, at least to the naked eye, the Sun always appears to be the same. However, this external constancy hides relatively slow but significant changes.

First of all, they are expressed in fluctuations in the number of sunspots, these local, darker areas solar surface, where, due to weakened convection, the solar gases are somewhat cooled and therefore appear dark due to the contrast. Usually, astronomers calculate for each moment of observation not the total number of spots visible on the solar disk, but the so-called Wolf number, equal to the number of spots added to ten times the number of their groups. Characterizing the total area of ​​sunspots, the Wolf number changes cyclically, reaching a maximum on average every 11 years. How more number Wolf, the higher the solar activity. During the years of maximum solar activity, the solar disk is abundantly dotted with spots. All processes on the Sun become violent. In the solar atmosphere, prominences are more often formed - fountains of hot hydrogen with a small admixture of other elements. Solar flares appear more often, these most powerful explosions in the surface layers of the Sun, during which dense streams of solar corpuscles - protons and other nuclei of atoms, as well as electrons - are "shot" into space. Corpuscular flows -- solar plasma. They carry with them a weak magnetic field with a strength of 10 -4 oersted "frozen" in them. Reaching the Earth on the second day, or even earlier, they excite the Earth's atmosphere, perturb the Earth's magnetic field. Other types of radiation from the Sun are also intensifying, and the Earth sensitively responds to solar activity.

If the Sun is like a string, then there must certainly be many cycles of solar activity. One of them, the longest and largest in amplitude, sets the "basic tone". Cycles of shorter duration, that is, "overtones", should have less and less amplitude.

Of course, the string analogy is incomplete. All string vibrations have strictly defined periods; in the case of the Sun, we can only talk about some, only on average, certain cycles of solar activity. Nevertheless, different cycles of solar activity should be proportional to each other on average. Surprising as it may seem, the expected similarity between the Sun and the string is confirmed by the facts. Simultaneously with the clearly defined eleven-year cycle, another, doubled, twenty-two-year cycle also operates on the Sun. It manifests itself in a change in the magnetic polarities of sunspots.

Each sunspot is a strong "magnet" with a strength of several thousand oersteds. Spots usually appear in close pairs, with the line connecting the centers of two neighboring spots parallel to the solar equator. Both spots have different magnetic polarities. If the front, head (in the direction of rotation of the Sun) spot has a north magnetic polarity, then the next spot after it has a south polarity.

It is remarkable that during each eleven-year cycle all head spots of different hemispheres of the Sun have a different polarity. Once every 11 years, as if on command, the polarity of all the spots changes, which means that the initial state is repeated every 22 years. We do not know what the reason for this phenomenon is, but its reality is undeniable.

There is also a triple, thirty-three-year cycle. It is not yet clear in what solar processes it is expressed, but its terrestrial manifestations have long been known. So, for example, especially severe winters are repeated every 33-35 years. The same cycle is noted in the alternation of dry and wet years, fluctuations in the level of lakes, and, finally, in the intensity of auroras - phenomena that are obviously associated with the Sun.

On the cuts of trees, an alternation of thick and thin layers is noticeable - again with an average interval of 33 years. Some researchers (for example, G. Lungershausen) believe that thirty-three-year cycles are also reflected in the layering of sedimentary deposits. In many sedimentary rocks ah, microlayering is observed due to seasonal changes. The winter layers are thinner and lighter due to the depletion of organic material, the spring-summer layers are thicker and darker, since they were deposited during a period of more vigorous manifestation of rock weathering factors and the vital activity of organisms. In marine and oceanic biogenic sediments, such phenomena are also observed, since they accumulate the remains of microorganisms, which are always much larger during the growing season than in the winter period (or during the dry period in the tropics). Thus, in principle, each pair of microlayers corresponds to one year, although it happens that two pairs of layers can correspond to a year. The reflection of seasonal changes in sedimentation can be traced for almost 400 million years - from the Upper Devonian to the present day, however, with rather long breaks, sometimes taking tens of millions of years (for example, in the Jurassic period, which ended about 140 million years ago).

Seasonal stratification is associated with the movement of the Earth around the Sun, the inclination of the Earth's axis of rotation relative to the plane of its orbit (or the solar equator, which is practically the same), the nature of the circulation of the atmosphere, and many others. But as we have already mentioned, some researchers see seasonal layering as a reflection of thirty-three-year cycles of solar activity, although if we can talk about this, then only for the so-called ribbon deposits (in clays and sands) of the last glaciation. But if this is so, then it turns out that for at least millions of years, an amazing and so far poorly studied mechanism of solar activity has been operating. Nevertheless, it should be noted once again that it is difficult to clearly distinguish any definite cycles associated with solar activity in geological deposits. Climate fluctuations in ancient times are primarily associated with changes on the surface of the Earth, with an increase or, conversely, a decrease in the total area of ​​the seas and oceans - these main accumulators of solar heat. Indeed, glacial epochs were always preceded by high tectonic activity of the earth's crust. But this activity, in turn (which will be discussed later), can be stimulated by an increase in solar activity. The data seems to be talking about it. recent years. In any case, there is still much unclear in these questions, and therefore the further discussion in this chapter should be considered only as one of the possible hypotheses.

Even in the last century, it was noticed that the maxima of solar activity are not always the same. In the changes in the values ​​of these maxima, a “secular” or, more precisely, an 80-year cycle is outlined, approximately seven times longer than an eleven-year one. If "secular" fluctuations in solar activity are compared with waves, cycles of shorter duration will look like "ripples" on the waves.

The "secular" cycle is quite clearly expressed in the frequency of solar prominences, fluctuations in their average heights, and other phenomena on the Sun. But its earthly manifestations are especially noteworthy.

The "secular" cycle is now expressed in the next warming of the Arctic and Antarctic. After some time, warming will be replaced by cooling, and these cyclic fluctuations will continue indefinitely. "Secular" climate fluctuations are also noted in the history of mankind, in chronicles and other historical chronicles. Sometimes the climate became unusually harsh, sometimes unusually mild. So, for example, in 829 even the Nile was covered with ice, and from the 12th to the 14th centuries the Baltic Sea froze several times. On the contrary, in 1552 an unusually warm winter complicated Ivan the Terrible's campaign against Kazan. However, not only the “secular” cycle is involved in climate fluctuations.

If on the graph of changes in solar activity we connect the points of maxima and points of minima of two adjacent "secular" cycles with straight lines, then it turns out that both straight lines are almost parallel, but inclined to the horizontal axis of the graph. In other words, some kind of long, centuries-old cycle is outlined, the duration of which can only be established by means of geology.

On the shores of Lake Zurich there are ancient terraces - high cliffs, in the thickness of the rocks of which layers of different eras are clearly distinguishable. And in this layering of sedimentary rocks, apparently, an 1800-year rhythm has been recorded. The same rhythm is noticeable in the alternation of silty deposits, the movement of glaciers, fluctuations in moisture and, finally, in cyclic climate changes.

In the book of the Soviet geographer Professor G.K. Tushinsky summarized everything known about the 1800-year cycle, and most importantly, traced its manifestations in the history of the Earth. Here we mention only briefly that the periodic drying and moistening of the Sahara, a strong and prolonged warming of the Arctic, during which the Normans settled Greenland (Green Land) and discovered America, are probably associated with the 1800-year cycle. On the waves of the 1800-year cycle, even the "secular" cycle looks like a "ripple".

If the average temperature of the Earth drops by only four to five degrees, a new ice age will come. Ice shells will cover almost all North America, Europe and much of Asia. On the contrary, an increase in the average annual temperature of the Earth by only two or three degrees will make the ice cover of Antarctica melt, which will raise the level of the World Ocean by 70 m with all the ensuing catastrophic consequences (flooding of a significant part of the continents). Thus, small fluctuations in the average temperature of the Earth (just a few degrees) can throw the Earth into the arms of glaciers or, conversely, cover most of the land with an ocean.

It is well known that glacial epochs and periods have been repeated many times in the history of the Earth, and warming epochs have come between them. They were very slow, but grandiose climate change, which were superimposed by smaller amplitude, but more frequent and rapid climate fluctuations, when ice ages were replaced by periods of warm and humid.

The intervals between glacial epochs or periods can only be characterized as an average: after all, cycles operate here, and not exact periods. According to the research of the Soviet geologist G.F. Lungershausen, glacial epochs were repeated in the history of the Earth approximately every 180–200 million years (according to other estimates, 300 million years). Ice ages within glacial epochs alternate more often, on average, after several tens of thousands of years. And all this is recorded in the thickness of the earth's crust, in the deposits of rocks of various ages.

The reasons for the change of ice ages and periods are not known for certain. Many hypotheses have been proposed to explain glacial cycles by cosmic causes. In particular, some scientists believe that, revolving around the center of the Galaxy with a period of 180-200 million years, the Sun, together with the planets, regularly passes through the thickness of the plane of the arms of the Galaxy, enriched with dusty matter, which weakens solar radiation. However, no nebulae are visible in the Sun's galactic path that could play the role of a dark filter. And most importantly, the cosmic dusty nebulae are so rarefied that, having plunged into them, the Sun for an earthly observer would still remain dazzlingly bright.

According to the hypothesis of M.S. Eigenson, all cyclical climate fluctuations, ranging from the most insignificant to alternating ice ages, are explained by one reason - rhythmic fluctuations in solar activity. And since the Sun is like a string in this process, then all cycles of solar activity should manifest themselves in the fluctuations of the earth's climate - from the "main" cycle of 200 or 300 million years to the shortest, eleven years. The very "mechanism" of the impact of the Sun on the Earth in this case boils down to the fact that fluctuations in solar activity immediately cause changes in the geomagnetosphere and circulation of the Earth's atmosphere.

If the Earth did not rotate, the circulation of air masses would be extremely simple. In the warm tropical zone of the Earth, heated and therefore less dense air rises. The pressure difference between the pole and the equator causes these air masses to rush towards the pole. Here, having cooled down, they fall down, in order to then again move to the equator. So in the case of the immobility of the Earth, the "heat engine" of the planet would work.

The axial rotation of the Earth and its revolution around the Sun complicate this idealized picture. Under the influence of the so-called Coriolis forces (forcing rivers flowing in the meridional direction to wash away the right bank in the northern hemisphere, and the left bank in the southern hemisphere), air masses circulate from the equator to the pole and back in spirals. In the same periods when the air near the equator is heated especially strongly, there is a wave circulation of air masses. Spiral movement is combined with wave movement, and therefore the direction of the winds is constantly changing. In addition, uneven heating of various parts of the earth's surface and relief complicate this difficult picture. If air masses move parallel to the earth's equator, the air circulation is called zonal, if along the meridian - meridional.

For an eleven-year solar cycle, it has been proven that with an increase in solar activity, zonal circulation weakens and meridional circulation intensifies. The earth's "heat engine" works more energetically, enhancing heat exchange between the polar and equatorial zones. If in a glass of cold water pour a little boiling water, then the water will heat up more quickly if you stir it with a spoon. For the same reason, during periods of increased solar activity, the atmosphere “excited” by solar radiation provides, on average, a warmer climate than during the years of the “passive” Sun.

This is true for any solar cycles. But the longer the cycle, the more it reacts to it. earth atmosphere the more the Earth's climate changes.

“The cosmic cause of glacial or, better, cold epochs,” writes M.S. Eigenson, - cannot in any way consist in lowering the temperature. The situation is "only" in the fall in the intensity of the meridional air exchange and in the growth of the meridional thermal gradient due to this fall ... "

Therefore, the physical fundamental basis of climatic differences is the general circulation of the atmosphere.

The role of solar rhythms in the history of the Earth is very noticeable. The general circulation of the atmosphere predetermines the speed of winds, the intensity of water exchange between the geospheres, and hence the nature of weathering processes. The sun apparently also influences the rate of formation of sedimentary rocks. But then, according to M.S. Eigenson, geological epochs with increased general circulation of the atmosphere and hydrosphere should correspond to soft, poorly expressed landforms. On the contrary, during long epochs of reduced solar activity, the earth's relief should acquire contrast.

On the other hand, during cold epochs, significant ice loads apparently stimulate vertical movements in earth's crust, that is, they activate tectonic activity. Finally, it has long been known that volcanism intensifies during periods of solar activity.

Even in the oscillations of the earth's axis (in the body of the planet), as I.V. Maksimov, the eleven-year solar cycle has an effect. This, apparently, is explained by the fact that the active Sun redistributes the air masses of the earth's atmosphere. Consequently, the position of these masses relative to the axis of rotation of the Earth also changes, which causes its insignificant, but still quite real displacements and changes the speed of rotation of the Earth. But if changes in solar activity affect the entire Earth as a whole, then the more noticeable should be the impact of solar rhythms on the surface shell of the Earth.

Any, especially sharp, fluctuations in the speed of the Earth's rotation should cause tension in the earth's crust, the movement of its parts, and this, in turn, can lead to cracks, which stimulates volcanic activity. This is how it is possible (of course, in the most general terms) to explain the connection of the Sun with volcanism and earthquakes.

The conclusion is clear: it is hardly possible to understand the history of the Earth without taking into account the influence of the Sun. At the same time, however, one must always keep in mind that the influence of the Sun only regulates or perturbs the processes of the Earth's own development, which is subject to its own geological internal laws. The sun makes only some "corrections" in the evolution of the Earth, without being at all, of course, driving force this evolution.

Imagine a clear sunny day, a brightly shining solar disk in the sky, Nature lives its ordinary life. But here, on the right edge of the Sun, a small damage first gradually appears, then it slowly increases, and as a result, until recently, the former round disk takes the form of a sickle. Sunlight gradually weakens, it becomes cooler. The resulting crescent becomes very small, and eventually the last flashes of light disappear behind the black disk. A clear day instantly turns into night, stars appear in the darkened sky, a lemon-orange dawn flashes from all sides, and a black circle gapes in place of the Sun, surrounded by an indistinct silvery glow. Frightened by the onset of darkness, animals and birds abruptly fall silent, and almost all plants roll up their leaves. But a few minutes will pass, and the Sun will again reveal its triumphant face to the world and Nature will come to life. For thousands of years, the phenomenon of a solar eclipse inspired people with both fear and awe.

If total solar eclipses were visible in every locality often enough, one would get used to them as quickly as one would get used to changes in the phases of the moon. But they happen so rarely that not every generation of local residents manages to see them at least once - at one point on the earth's surface, total solar eclipses can be observed only once every 300-400 years. Lunar eclipses, especially total ones, were no less feared than solar ones. After all, this night star sometimes completely disappeared from the vault of heaven, and the darkened part of the moon soon took on a gray color with a reddish sheen, becoming more and more blood-dark. In ancient times, lunar eclipses were attributed a special sinister influence on earthly events. The ancients believed that the moon at this moment is shedding blood, which promises great disasters for mankind. The first lunar eclipse recorded in ancient Chinese chronicles dates back to 1136 BC.

To understand the cause of solar and lunar eclipses, priests for centuries kept count of total and partial eclipses. First, it was noticed that the lunar ones occur only on the full moon, and the solar ones only on the new moon, then that solar eclipses do not occur at every new moon and lunar eclipses do not occur at every full moon, and also that solar eclipses did not happen when the moon was visible. Even during a solar eclipse, when the light was completely dimmed, and the stars and planets began to peep through the unnaturally dark twilight, the moon was nowhere to be seen. This aroused curiosity and gave rise to a careful study of the place where the Moon should have been immediately after the end of the solar eclipse. It was soon discovered that on the night following the day of a solar eclipse, the Moon was always in its nascent form very close to the Sun. Noticing the location of the Moon before the solar eclipse and immediately after it, they determined that during the eclipse itself, the Moon really passed from the western to the eastern side of the place occupied by the Sun, and complex calculations showed that the coincidence of the Moon and the Sun in the sky took place exactly at the time when The sun was darkening. The conclusion became obvious: the Sun is obscured from the Earth by the dark body of the Moon.

After finding out the causes of the solar eclipse, we moved on to unraveling the mystery of the lunar one. Although in this case it was much more difficult to find a satisfactory explanation, since the light of the moon was not obscured by any opaque body that stood between the night luminary and the observer. Finally, it has been observed that all opaque bodies cast a shadow in the direction opposite to the light source. It has been suggested that, perhaps, the Earth, illuminated by the Sun, gives that shadow, reaching even to the Moon. It was necessary to either confirm or disprove this theory. And it was soon proved that lunar eclipses occur only during the full moon. This confirmed the assumption that the cause of the eclipse is the shadow from the Earth falling on the Moon - as soon as the Earth became between the Moon and the light source - the Sun, the light of the Moon, in turn, became invisible and an eclipse occurred.

As a result of long-term observations, it turned out that both lunar and solar eclipses inevitably repeat in the same order after the expiration of the time interval through which the mutual position of the Sun, Moon and nodes of the lunar orbit is repeated. The ancient Greeks called this gap the saros. It is 223 revolutions of the moon, that is, 18 years, 11 days and 8 hours. After the expiration of the saros, all eclipses are repeated, but under somewhat different conditions, since in 8 hours the Earth rotates by 120 °, and therefore moon Shadow will move 120° west across the Earth than it was 18 years ago. The ancient Egyptians, Babylonians, Chaldeans and other "cultural" peoples as early as 2500 BC, not knowing the reasons for the eclipse, were able to predict their onset with an accuracy of 1-2 days within their limited territory. But since they could not have the results of observations on everything the globe, they used for calculations a triple, or large, saros containing an integer number of days. The sequence of solar and lunar eclipses after the triple Saros is repeated at the same geographic longitude. It is believed that a large saros - namely 19,756 days - was first calculated by the ancient Babylonian astronomers-priests. The establishment of the saros was one of the greatest discoveries of antiquity, as it led to the discovery of the true cause of eclipses as early as the 6th century BC.

The earliest written evidence of a solar eclipse dates back to October 22, 2137 BC. Moreover, this eclipse was not predicted by court astronomers, and therefore the horror of the unexpectedly coming night was extremely great. However, those ancient astronomers could hardly be accused of negligence, since in those days the prediction of such phenomena in any particular place was not an easy task at all. It is impossible to make an accurate forecast of the eclipse from the saros, it was possible to indicate only the approximate date and area of ​​​​its visibility. It was a difficult task to accurately calculate the time of the eclipse, as well as the conditions for its visibility. And to solve it, astronomers have been studying the motion of the Earth and the Moon for several centuries. Eclipses are currently a high degree accuracies are calculated both for thousands of years ago and for hundreds of years ahead.

The study of ancient solar eclipses helps modern scientists correct the dates of many historical events and even change their sequence. After all, each total solar eclipse occurs in a certain and rather narrow strip of the earth's surface, the position of which changes from year to year. And therefore, according to the area where it took place, it is possible, with the help of calculations, to absolutely accurately determine their date. In addition, by comparing the movements of the moon's shadow over the earth's surface, one can establish the natural evolution of the motion of the moon. It was this comparison that first led scientists to the idea of ​​a secular deceleration of the Earth's rotation, which is 0.0014 seconds per century.

A total solar eclipse is a unique opportunity to study the outer layers of the Sun's atmosphere - the chromosphere and corona. And although their observations are carried out daily, this is not enough. The corona is only visible during a total solar eclipse, as the brightness of the corona's light is a million times less than that of the disk's light. In addition, light from the Sun's disk is scattered by the Earth's atmosphere and the brightness of this scattered light is close to that of the corona. The brightest part of the Sun, the one that appears yellow to us, is called the photosphere. During a total eclipse, the lunar disk completely covers the photosphere. Only after the photosphere hides behind the Moon can the chromosphere be seen for a short time in the form of a ragged red ring surrounding a black disk.

The solar corona extends far from the Sun - to the orbits of Jupiter and Saturn. During the 11-year cycle of solar activity, both the shape of the corona and its overall brightness change. Extremely interesting were the spectra of the corona taken near the solar disk. Against the background of the continuous spectrum, bright emission lines were visible, which for many years were one of the most important for science. the greatest mysteries. It was allowed only in the 40s of the XX century. It turned out that these lines emit strongly ionized iron and calcium atoms, the existence of which requires temperatures reaching a million degrees.

important role in clarifying the physical conditions existing in solar corona, played the so-called eclipsing observations, in particular radio astronomy. To date, one of the main tasks is to study the infrared radiation of interplanetary dust. During eclipses, photometric, colorimetric, spectrophotometric and polarimetric observations are also performed. There is also no doubt that eclipsing observations of the Sun have made an invaluable contribution to scientists' understanding of the Sun and the interstellar medium.

In order to fruitfully use the few minutes during which an eclipse occurs, astronomers prepare for it for many months, making accurate calculations of the eclipse band, studying weather reports in the eclipse band, and looking for the best place to observe. At the same time, the issues of transportation and provision of the necessary facilities, such as electricity and water, are being resolved; in parallel, observation programs are being drawn up and appropriate instruments are being designed. The more inaccessible the place of observation, the more necessary to insure yourself against various accidents.

Observation of a solar eclipse can also be successfully used to study the earth's atmosphere. For this purpose, observations are made of changes in temperature, pressure, humidity, wind, cloud formation, photometric observations of the brightness and color of the sky, and so on. During eclipses it also becomes possible to recognize deviations in the motion of the Moon and the rotation of the Earth. The study of the ionosphere carried out during eclipses with the help of radio waves makes it possible to study the influence of the sun on the upper layers of the earth's atmosphere.

A significant achievement of eclipse observers can rightfully be considered the verification of the effect of the gravitational influence of massive space objects(in particular, the Sun) to light rays, predicted in the framework of Einstein's theory of relativity. To do this, it was necessary to use the same telescope to take pictures of the stars that are as close as possible to the edge of the Sun during the eclipse, and after a few months to take these same stars already in the night sky. After measuring the relative positions of the images of these stars in two photographs, it was possible to judge whether they had shifted. For the first time this experiment was carried out in 1919, confirming the validity of the conclusions of Einstein's theory.

It remains to add that the next total solar eclipse will occur on December 4, 2002. It will start at South Africa and will end in Australia, and its maximum duration will be 2 minutes 4 seconds. All professional astronomers, as well as amateur astronomers, are already preparing for this event.

Solar eclipses are by no means visible from all areas of the Earth's daytime hemisphere, since, due to its small size, the Moon cannot hide the Sun from the entire Earth's hemisphere. Its diameter is less than the diameter of the Sun by about 400 times, but at the same time, the Moon is almost 400 times closer to the Earth compared to the Sun, so the apparent sizes of the Moon and the Sun are almost the same, so the Moon, albeit in a very limited area, can cover us from Sun.
The nature of the eclipse depends on the distance of the Moon from the Earth, and, since the orbit of the Moon is not circular, but elliptical, this distance changes, and depending on this, the apparent size of the Moon also changes slightly. If at the time of a solar eclipse the Moon is closer to the Earth, then the lunar disk, being slightly larger than the sun, will completely cover the Sun, which means that the eclipse will be total. If - further, then its visible disk will be smaller than the solar one and the Moon will not be able to close the entire Sun - a bright rim will remain around it. Such an eclipse is called an annular eclipse.

Illuminated by the Sun, the Moon casts into space a converging cone of shadow and penumbra surrounding it. When these cones intersect with the Earth, the lunar shadow and penumbra fall on it. A spot of the lunar shadow with a diameter of about 300 km runs along the earth's surface, leaving a trail 10-12 thousand km long, and where it passes, a total solar eclipse occurs, while in the area captured by penumbra, a partial eclipse occurs, when only part of the solar disk. It often happens that the lunar shadow passes the Earth, and the penumbra partially captures it, then only partial eclipses occur.

Since the speed of movement of the shadow on the surface of the Earth, depending on geographical latitude ranges from 2000 km/h (near the equator) to 8000 km/h (near the poles), a total solar eclipse observed at one point lasts no more than 7.5 minutes, and the maximum value is reached in very rare cases (the nearest eclipse lasting 7 min 29 seconds will only occur in 2186).

A solar eclipse begins in the western regions of the earth's surface at sunrise and ends in the eastern regions at sunset. Total duration of all phases of a solar eclipse on Earth can reach 6 hours. The degree of coverage of the Sun by the Moon is called the phase of the eclipse. It is defined as the ratio of the closed part of the diameter of the solar disk to its entire diameter. With partial eclipses of weakening sunlight is not noticeable (with the exception of eclipses with a very large phase), and therefore the phases of the eclipse can only be observed through a dark filter.

Lunar eclipses occur when the full moon passes near the nodes of its orbit. Depending on whether it is partially or completely immersed in the earth's shadow, both partial and total shadow lunar eclipses occur. Near the lunar nodes, within 17° on either side of them, there are zones of lunar eclipses. The closer to the lunar node an eclipse occurs, the greater its phase, determined by the proportion of the lunar diameter covered by the earth's shadow. The entry of the Moon into the shadow or penumbra of the Earth usually goes unnoticed. A total eclipse is preceded by partial phases, and at the moment of the final immersion of the Moon into the earth's shadow, it occurs, lasting about two hours. The frequency of lunar eclipses for any particular place on Earth is higher than the frequency of solar eclipses only because they are visible from the entire night hemisphere of the Earth. In this case, the duration of the total phase of a solar eclipse on the Moon can reach 2.8 hours.

Observations of total lunar eclipses make it possible to study the structure and optical properties of the earth's atmosphere, as well as the thermal properties of various parts of the lunar surface, including the change in their temperature during different phases of the eclipse.

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 phase value 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. If you compare pictures of total lunar eclipses from different years, it's 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 of the time the Moon spends 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 of this or that 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 ended up in plight, 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 should 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 registration 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 it can be used to 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, there is usually no need for additional magnifying tools, because. the dimensions of the moon at the maximum magnification of such a camera are sufficient for filming.

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