Rice. 5. Solar eclipse.

Let's look closely at this general educational picture of the origin of a solar eclipse.

The direction of the Earth's movement is counterclockwise, from west to east red arrow.
If the moon were static, then the shadow of the moon would shift to opposite side, to the west, black shooters.
However, the Moon is moving in the direction of the Earth's rotation ( along the red arrow), its orbital speed is more than twice the speed of its rotation. That is why the movement of the moon's shadow on the earth's surface from west to east is observed. But with what speed should the shadow move away from the observer on the ground to the left, i.e. towards the east (observer facing south) - the question is open? … open for discussion!

So, let's sum up some results in our study of the motion of the Moon.

The Moon is moving to the left of the stationary stellar sphere (for an observer from the earth facing south), from west to east, in the direction of the rotation of the Earth itself, but faster, at a rate of one revolution in 27.3 days, 13.2 ° per day, or 1,023 km/s D lights up the Sun and "runs" on it from the right during a solar eclipse. This happens because the Sun moves along the signs of the zodiac also to the east, making a full circle in 365.24 days, slower than 1 ° per day.

The shadow of the Moon moves to the left, overtakes the rotation of the Earth, passes along the earth's surface from west to east.

For the observer from the Earth (in the northern hemisphere), the picture of the eclipse itself, the displacement of the luminaries of the Sun and the Moon will occur to the right, to the west, i.e. from sunrise to sunset. This movement is connected with the rotation of the Earth around its axis from west to east.

Some questions raised in the topic remain open, I will be glad to hear answers and justifications.

I myself will try in the next part to clarify these issues, based on the actual rotation of the moon.
To be continued…

Earthly life owes its origin to the heavenly body. It warms and illuminates everything on the surface of our planet. No wonder the worship of the Sun and its representation as a great heavenly god was reflected in the cults of the primitive peoples who inhabited the Earth.

Centuries, millennia have passed, but its importance in human life has only increased. We are all children of the Sun.

What is the Sun?

star from the galaxy Milky Way, his geometric shape, representing a huge, hot, gaseous ball, constantly radiating energy flows. The only source of light and heat in our star-planetary system. Now the Sun is in the age of a yellow dwarf, according to the generally accepted classification of the types of stars in the universe.

Characteristics of the Sun

The sun has the following properties:

• Age -4.57 billion years;
• Distance to Earth: 149,600,000 km
• Mass: 332,982 Earth masses (1.9891 10³⁰ kg);
• The average density is 1.41 g / cm³ (it increases 100 times from the periphery to the center);
• The orbital speed of the Sun is 217 km/s;
• Rotation speed: 1.997 km/s
• Radius: 695-696 thousand km;
• Temperature: from 5,778 K on the surface to 15,700,000 K in the core;
• Corona temperature: ~1,500,000 K;
• The sun is stable in its brightness, it is in the 15% of the most bright stars our Galaxy. It emits less ultraviolet rays, but has a greater mass compared to similar stars.

What is the sun made of?

In my own way chemical composition our star is no different from other stars and contains: 74.5% hydrogen (by mass), 24.6% helium, less than 1% other substances (nitrogen, oxygen, carbon, nickel, iron, silicon, chromium, magnesium and others). Inside the nucleus, there are continuous nuclear reactions that turn hydrogen into helium. The absolute majority of the mass solar system- 99.87% belongs to the Sun.

Already this Saturday, August 11, 2018, a new mission to study the Sun - the Parker Solar Probe (or the Parker solar probe) will go into space. In a few years, the device will come closer to the Sun than any man-made object has yet managed to do. Editorial N+1 With the help of Sergei Bogachev, chief researcher at the Laboratory of X-ray Solar Astronomy at the Lebedev Physical Institute, she decided to find out why scientists send the device to such a hot place and what results are expected from it.

When we look at the night sky, we see a huge number of stars - the most numerous category of objects in the universe that can be observed from Earth. It is these huge shining gas balls that are produced in their thermonuclear "furnaces" by many chemical elements heavier than hydrogen and helium, without which our planet, and all life on it, and ourselves would not exist.

The stars are at great distances from the Earth - the distance to the nearest of them, Proxima Centauri, is estimated at several light years. But there is one star whose light takes only eight minutes to reach us - this is our Sun, and observing it helps us learn more about other stars in the Universe.

The sun is much closer to us than it seems at first glance. In a certain sense, the Earth is inside the Sun - it is constantly washed by the flow of the solar wind coming from the corona - the outer part of the star's atmosphere. It is the streams of particles and radiation from the Sun that control the "space weather" near the planets. The emergence of auroras and disturbances in the magnetospheres of the planets depends on these streams, while solar flares and coronal mass ejections disable satellites, affect the evolution of life forms on Earth, and determine the radiation load on manned space missions. Moreover, similar processes occur not only in the solar system, but also in other planetary systems. Therefore, understanding the processes in the solar corona and the inner heliosphere allows us to better navigate the behavior of the plasma "ocean" surrounding the Earth.

Structure of the Sun

Wikimedia Commons

“Due to the remoteness of the Sun, we receive almost all information about it through the radiation it generates. Even some simple parameters, such as temperature, which can be measured with an ordinary thermometer on Earth, are determined for the Sun and stars in a much more complicated way - by their radiation spectrum. This also applies to more complex characteristics, such as the magnetic field. The magnetic field is able to influence the radiation spectrum, splitting the lines in it - this is the so-called Zeeman effect. And it is precisely due to the fact that the field changes the radiation spectrum of the star that we are able to register it. If such an influence did not exist in nature, then we would not know anything about the magnetic field of stars, since there is no way to directly fly up to a star, ”says Sergey Bogachev.

“But this method also has limitations - take at least the fact that the absence of radiation deprives us of information. If we talk about the Sun, then the solar wind does not emit light, so there is no way to remotely determine its temperature, density and other properties. Does not emit light or magnetic field. Yes, in the lower layers of the solar atmosphere magnetic tubes are filled with luminous plasma and this makes it possible to measure the magnetic field near the surface of the Sun. However, already at a distance of one solar radius from its surface, such measurements are impossible. And there are many such examples. How to be in such a situation? The answer is very simple: you need to launch probes that can fly directly to the Sun, plunge into its atmosphere and into the solar wind, and take measurements directly on the spot. Such projects are widespread, although less known than those of space telescopes, which make remote observations and provide much more spectacular data (such as photographs) than probes that produce boring streams of numbers and graphs. But if we talk about science, then, of course, few remote observations can be compared in strength and persuasiveness with the study of an object that is located nearby, ”continues Bogachev.

Mysteries of the Sun

Observations of the Sun have been made since Ancient Greece and in Ancient Egypt, and over the past 70 years, more than a dozen space satellites, interplanetary stations and telescopes, ranging from Sputnik-2 to space observatories operating today, such as SDO, SOHO or STEREO, have closely monitored (and are monitoring) the behavior of the closest to us the stars and its surroundings. Nevertheless, astronomers still have many questions related to the structure of the Sun and its dynamics.

For example, for more than 30 years, scientists have been facing the problem of solar neutrinos, which consists in the lack of registered electron neutrinos produced in the core of the Sun as a result of nuclear reactions, compared with their theoretically predicted number. Another mystery is related to the anomalous heating of the corona. This outermost layer of the star's atmosphere has a temperature of more than a million degrees Kelvin, while the visible surface of the Sun (the photosphere), above which the chromosphere and corona are located, is heated to only six thousand degrees Kelvin. This seems strange, because logically, the outer layers of the star should be colder. Direct heat transfer between the photosphere and the corona is not enough to provide these temperatures, which means that other coronal heating mechanisms are at work here.

The corona of the Sun during the total solar eclipse in August 2017.

NASA's Goddard Space Flight Center/Gopalswamy

There are two main theories to explain this anomaly. According to the first one, magnetoacoustic waves and Alfven waves are responsible for heat transfer from the convective zone and photosphere of the Sun to the chromosphere and corona, which, being scattered in the corona, increase the plasma temperature. However, this version has a number of disadvantages, for example, magnetoacoustic waves cannot ensure the transfer of a sufficiently large amount of energy to the corona due to scattering and reflection back to the photosphere, and Alfvén waves convert their energy into thermal plasma energy relatively slowly. In addition, for a long time there was simply no direct evidence of wave propagation through the solar corona - it was not until 1997 that the SOHO space observatory first recorded magnetoacoustic solar waves at a frequency of one millihertz, which provide only ten percent of the energy needed to heat the corona to the observed temperatures.

The second theory relates the anomalous heating of the corona to constantly occurring microflares arising from the continuous reconnection of magnetic lines in local regions of the magnetic field in the photosphere. This idea was proposed in the 1980s by the American astronomer Eugene Parker, whose name is the probe and who also predicted the presence of the solar wind, a stream of high-energy charged particles continuously emitted by the Sun. However, the theory of microoutbursts has not yet been confirmed either. It is possible that both mechanisms work on the Sun, but this needs to be proven, and for this it is necessary to fly up to the Sun at a fairly close distance.

Another secret of the Sun is connected with the corona - the mechanism of the formation of the solar wind that fills the entire solar system. It is on him that such phenomena depend. space weather like northern lights or magnetic storms. Astronomers are interested in the mechanisms of origin and acceleration of the slow solar wind, born in the corona, as well as the role of magnetic fields in these processes. Here too, there are several theories with both evidence and flaws, and it is expected that the Parker probe will help to dot the i's.

“In general, at present, there are sufficiently developed models of the solar wind that predict how its characteristics should change as it moves away from the Sun. The accuracy of these models is quite high at distances of the order of the Earth's orbit, but it is not clear how accurately they describe the solar wind at close distances from the Sun. Perhaps Parker can help with that. Still pretty interest Ask- acceleration of particles on the Sun. After flares, streams of a large number of accelerated electrons and protons come to the Earth. It is not completely clear, however, whether their acceleration occurs directly on the Sun, and then they simply move towards the Earth by inertia, or whether these particles are additionally (and maybe completely) accelerated on their way to the Earth by interplanetary magnetic field. Perhaps, when data collected by a probe near the Sun arrives on Earth, this issue can also be dealt with. There are several other similar problems that can be solved in the same way - by comparing similar measurements near the Sun and at the level of the Earth's orbit. In general, the mission is aimed at solving such issues. We can only hope that the device will be successful,” says Sergey Bogachev.

Straight into hell

The Parker probe will be launched on August 11, 2018 from the launch complex SLC-37 at Cape Canaveral Air Force Base, it will be launched into space by a heavy launch vehicle Delta IV Heavy - this is the most powerful rocket in operation, it can launch into low orbit almost 29 tons of cargo. In terms of carrying capacity, it is surpassed only by, but this carrier is still in the testing stage. To get to the center of the solar system, it is necessary to extinguish the very high speed that the Earth (and all objects on it) has relative to the Sun - about 30 kilometers per second. In addition to a powerful rocket, this will require a series of gravitational maneuvers near Venus.

According to the plan, the process of approaching the Sun will last seven years - with each new orbit (there are 24 in total), the device will come closer to the star. The first perihelion will be passed on November 1, at a distance of 35 solar radii (about 24 million kilometers) from the star. Then, after a series of seven gravitational maneuvers near Venus, the device will approach the Sun to a distance of about 9-10 solar radii (about six million kilometers) - this will happen in mid-December 2024. That's seven times closer than the perihelion of Mercury's orbit, no man-made yet. spacecraft did not get so close to the Sun (the current record belongs to the Helios-B apparatus, which approached the star at 43.5 million kilometers).

Scheme of the flight to the Sun and the main working orbits of the probe.

The main stages of work on each of the orbits.

The choice of such a position for observations is not accidental. According to the calculations of scientists, at a distance of ten radii from the Sun is the Alfven point - the region where the solar wind accelerates so much that it leaves the Sun, and the waves propagating in the plasma no longer affect it. If the probe can be near the Alfven point, then we can assume that it entered the solar atmosphere and touched the Sun.

Probe "Parker" in the assembled state, during installation on the third stage of the launch vehicle.

"The task of the probe is to measure the main characteristics of the solar wind and the solar atmosphere along its trajectory. The scientific instruments on board are not unique, they do not have record characteristics (except for the ability to withstand solar radiation fluxes at the perihelion of the orbit). The Parker Solar Probe is a spacecraft with conventional instruments but in a unique orbit Most (perhaps even all scientific instruments) are planned to be kept off at all parts of the orbit except perihelion, where the spacecraft is closest to the Sun. scientific program additionally emphasizes that the main task of the mission is to study the solar wind and solar atmosphere. When the device moves away from perihelion, the data from the same instruments will turn into ordinary ones, and in order to save the resource of scientific instruments, they will simply be switched to the background until the next approach. In this sense, the ability to reach a given trajectory and the ability to live on it for a given time are the factors on which the success of the mission will primarily depend,” says Sergey Bogachev.

The device of the heat shield "Parker".

Greg Stanley/Johns Hopkins University

View of the heat shield at the stage of installation on the probe.

NASA/Johns Hopkins APL/Ed Whitman

Probe "Parker" with installed heat shield.

NASA/Johns Hopkins APL/Ed Whitman

To survive near the star, the probe is equipped with a heat shield that acts as an "umbrella" under which all scientific instruments will hide. The front of the shield will withstand temperatures in excess of 1,400 degrees Celsius, while the back of the shield, where the scientific instruments are located, must not exceed thirty degrees Celsius. Such a temperature difference is provided by the special design of this "solar umbrella". With a total thickness of just 11.5 centimeters, it consists of two panels made of carbon-graphite composite, between which there is a layer of carbon foam. The front of the shield has a protective coating and a white ceramic layer that increases its reflective properties.

In addition to the shield, the cooling system is designed to solve the problem of overheating, using 3.7 liters of pressurized deionized water as a coolant. The electrical wiring of the apparatus is made using high-temperature materials such as sapphire tubes and niobium, and during approaches to the Sun, the solar panels will be removed under the heat shield. In addition to strong heating, mission engineers will have to take into account strong light pressure from the Sun, which will interfere with the correct orientation of the probe. To facilitate this work, solar sensors are installed on the probe in different places, helping to control the protection of scientific equipment from the influence of the Sun.

Tools

Almost all scientific instruments of the probe are "sharpened" for the study of electromagnetic fields and the properties of the solar plasma surrounding it. The only exception is the optical telescope WISPR (Wide-field Imager for Solar PRobe), whose task will be to obtain images of the solar corona and solar wind, the inner heliosphere, shock waves and any other structures observed by the device.

The corona makes up the outer atmosphere of the Sun, passing in its outermost parts into the interplanetary medium. Outwardly, it looks like a silver and pearl radiance around the Sun. There are many details in it - rays, feathers, fans, arches, etc. During the years of maximum sunspots, the corona surrounds the entire Sun in a rather symmetrical manner and has a generally "disheveled" appearance (Fig. 27). During sunspot minimum years, it is compressed at the poles and extended along the equator (Fig. 28). Thus, to a certain extent, the corona is a product of solar activity.

The solar corona where it touches the chromosphere is incomparably brighter than, say, at a distance of 10-12 from the solar edge, and further on its brightness continues to decrease with height, but very slowly, so that it can be traced in good photographs up to distances from the edge Suns reaching several solar radii.

(click to view scan)

The limit here puts the brightness of the sky background, reaching high level even during very long eclipses. Photos taken during eclipses from high mountains and high-altitude aircraft, show the extension of the corona to a dozen or more degrees from the Sun, where the corona imperceptibly merges with the phenomenon of zodiacal light (see Chapter IX, § 39). The integral brightness of the corona is only one millionth of the brightness of the Sun (from to). Even its brightest parts were previously inaccessible to observations outside of eclipses.

Rice. 29. Fine structure of the inner crown. The photograph was taken outside the eclipse with a Lyot coronagraph in the light of the green coronal line

In spectral terms, the solar corona contains three components: L, K and F, L is an emission component consisting of two to three dozen bright lines extending to a height of about 9. These lines are visible against the background of the K-component - a continuous spectrum. At a height of about 3 from the edge of the Sun, a small amount of the F component, i.e., the Fraunhofer spectrum, qualitatively no different from the spectrum of the solar photosphere, begins to be mixed into the K spectrum. The F-spectrum is very clearly visible already at height 10, where the L-spectrum ends, and this height is considered the boundary of the inner corona (Fig. 29). Above lies the outer corona, whose spectrum at a height of 20 and more consists mainly of the F component. The integrated brightness of the F component is about the brightness of the Sun.

The light from the inner corona is markedly polarized. After a height of 10 above the edge, the polarization, reaching a value of about 45%, rapidly decreases.

We can assume that the K-component is polarized, while the F-component is not. The polarization is such that electric vector polarized component of light is perpendicular to the radius vector (in the picture plane) emanating from the center of the Sun.

The duration of observations of the solar corona during an eclipse along the entire band of the total phase is usually 2-3 hours. During this time, only the most insignificant movements are detected in the corona. But if the corona is systematically observed outside of eclipses on a Lyo coronograph, it is not difficult to notice changes in the corona from one day to the next. The repetition of the shape of the isophotes of the L-corona in the light of one or another line, as well as a steadily repeating increase in its radiation after about two weeks (the isophotes that were on one edge are transferred to the other edge of the Sun) and after four weeks (the isophotes are repeated on this edge) made it possible establish with full confidence the fact of the rotation of the corona and find the period of its rotation - it coincided with the period of rotation of the Sun, derived from sunspots and torches. Coronal formations, spots and plumes are inextricably linked.