The sun is the central luminary around which all the planets and small bodies of the solar system revolve. This is not only a center of gravity, but also a source of energy that ensures the heat balance and natural conditions on the planets, including life on Earth. The movement of the Sun relative to the stars (and the horizon) has been studied since ancient times to create calendars that people used primarily for agricultural purposes. The Gregorian calendar, now used almost everywhere in the world, is essentially a solar calendar based on the cyclic revolution of the Earth around the Sun*. The Sun has a visual magnitude of 26.74 and is the brightest object in our sky.
The Sun is an ordinary star located in our galaxy, simply called the Galaxy or the Milky Way, at a distance of ⅔ from its center, which is 26,000 light years, or ≈10 kpc, and at a distance of ≈25 pc from the plane of the Galaxy. It revolves around its center at a speed of ≈220 km/s and a period of 225–250 million years (galactic year) clockwise when viewed from the north galactic pole. The orbit is believed to be approximately elliptical and is perturbed by the galactic spiral arms due to non-uniform stellar mass distributions. In addition, the Sun makes periodic movements up and down relative to the plane of the Galaxy from two to three times per revolution. This leads to a change in gravitational perturbations and, in particular, has a strong influence on the stability of the position of objects at the edge of the solar system. This is the reason for the invasion of comets from the Oort Cloud into the solar system, which leads to an increase in impact events. In general, from the point of view of various kinds of perturbations, we are in a rather favorable zone in one of the spiral arms of our Galaxy at a distance of ≈ ⅔ from its center.
*The Gregorian calendar, as a time system, was introduced in Catholic countries by Pope Gregory XIII on October 4, 1582 to replace the previous Julian calendar, and the day after Thursday October 4 became Friday October 15. According to the Gregorian calendar, the length of the year is 365.2425 days and 97 out of 400 years are leap years.
In the modern era, the Sun is located near the inner side of the Orion Arm, moving inside the Local Interstellar Cloud (LIC) filled with rarefied hot gas, possibly the remnant of a supernova explosion. This region is called the galactic habitable zone. The Sun moves in the Milky Way (relative to other nearby stars) towards the star Vega in the constellation Lyra at an angle of approximately 60 degrees from the direction of the galactic center; it is called movement to the apex.
Interestingly, since our Galaxy is also moving relative to the cosmic microwave background radiation (CMB- Cosmic Microvawe Background) at a speed of 550 km/s in the direction of the constellation Hydra, the resulting (residual) velocity of the Sun relative to the CMB is about 370 km/s and is directed towards constellation Leo. Note that the Sun in its motion experiences small perturbations from the planets, primarily Jupiter, forming with it a common gravitational center of the solar system - the barycenter, located within the radius of the Sun. Every few hundred years, barycentric motion switches from forward (prograde) to reverse (retrograde).
* According to the theory of stellar evolution, less massive stars than T Tauri also move to MS along this track.
The Sun was formed about 4.5 billion years ago when the rapid contraction of a cloud of molecular hydrogen under the influence of gravitational forces led to the formation in our region of the Galaxy of a variable star of the first type of stellar population - a star of the type T Tauri (T Tauri). After the start of thermonuclear fusion reactions in the solar core (the conversion of hydrogen into helium), the Sun switched to the main sequence of the Hertzsprung–Russell (HR) diagram. The Sun is classified as a G2V yellow dwarf star, which appears yellow when viewed from Earth due to a slight excess of yellow light in its spectrum caused by blue light scattering in the atmosphere. The Roman numeral V in G2V means that the Sun belongs to the main sequence of the GR diagram. It is assumed that in the earliest period of evolution, before the transition to the main sequence, it was on the so-called Hayashi track, where it contracted and, accordingly, reduced its luminosity while maintaining approximately the same temperature *. Following an evolutionary scenario typical of low- and medium-mass main-sequence stars, the Sun has gone about halfway through the active phase of its life cycle (hydrogen-to-helium fusion) of a total of about 10 Gyr, and will continue to do so. activity over the next approximately 5 billion years. The Sun annually loses 10 14 of its mass, and the total loss throughout its life will be 0.01%.
By its nature, the Sun is a plasma ball with a diameter of approximately 1.5 million km. The exact values of its equatorial radius and mean diameter are 695,500 km and 1,392,000 km, respectively. This is two orders of magnitude larger than the Earth and an order of magnitude larger than Jupiter. […] The sun rotates counterclockwise around its axis (when viewed from the North Pole of the world), the speed of rotation of the outer visible layers is 7,284 km/h. The sidereal period of rotation at the equator is 25.38 days, while the period at the poles is much longer - 33.5 days, i.e. the atmosphere at the poles rotates more slowly than at the equator. This difference arises from differential rotation caused by convection and non-uniform mass transfer from the core to the outside, and is associated with the redistribution of angular momentum. As seen from Earth, the apparent rotation period is approximately 28 days. […]
The figure of the Sun is almost spherical, its oblateness is insignificant, only 9 millionths. This means that its polar radius is less than the equatorial one only by ≈10 km. The mass of the Sun is equal to ≈330,000 masses of the Earth […]. The sun contains 99.86% of the mass of the entire solar system. […]
About 1 billion years after entering the Main Sequence (estimated between 3.8 and 2.5 billion years ago), the brightness of the Sun increased by about 30%. It is quite obvious that the problems of the climatic evolution of the planets are directly related to the change in the luminosity of the Sun. This is especially true of the Earth, whose surface temperature, necessary for the preservation of liquid water (and, probably, the origin of life), could only be achieved by higher levels of greenhouse gases in the atmosphere to compensate for low insolation. This problem is called the "young sun paradox". In the subsequent period, the brightness of the Sun (as well as its radius) continued to slowly increase. According to existing estimates, the Sun becomes approximately 10% brighter every one billion years. Accordingly, the surface temperatures of the planets (including the temperature on Earth) are slowly rising. In about 3.5 billion years from now, the Sun's brightness will increase by 40%, by which time conditions on Earth will be similar to those on Venus today. […]
By the end of its life, the Sun will become a red giant. The hydrogen fuel in the core will be exhausted, its outer layers will greatly expand, and the core will shrink and heat up. Hydrogen fusion will continue along the shell surrounding the helium core, and the shell itself will constantly expand. More and more helium will be produced, and the temperature of the core will rise. When the temperature reaches ≈100 million degrees in the core, helium combustion will begin with the formation of carbon. This is probably the final phase of the Sun's activity, since its mass is insufficient to start the later stages of nuclear fusion involving heavier elements - nitrogen and oxygen. Due to the relatively small mass of the Sun, the life of the Sun will not end in a supernova explosion. Instead, intense thermal pulsations will occur, which will cause the Sun to shed its outer shells, and from them a planetary nebula will form. In the course of further evolution, a very hot degenerate core is formed - a white dwarf, devoid of its own sources of thermonuclear energy, with a very high density of matter, which will slowly cool and, as the theory predicts, will turn into an invisible black dwarf in tens of billions of years. […]
Solar Activity
The sun exhibits various types of activity, its appearance is constantly changing, as evidenced by numerous observations from Earth and from space. The most famous and most pronounced is the 11-year cycle of solar activity, which roughly corresponds to the number of sunspots on the surface of the Sun. Sunspots can be tens of thousands of kilometers across. They usually exist in pairs of opposite magnetic polarity that alternate each solar cycle and peak at maximum activity near the solar equator. As already mentioned, sunspots are darker and colder than the surrounding surface of the photosphere because they are regions of reduced energy of convective transport from hot interiors, suppressed by strong magnetic fields. The polarity of the Sun's magnetic dipole changes every 11 years in such a way that the north magnetic pole becomes south, and vice versa. In addition to changes in solar activity within an 11-year cycle, certain changes are observed from cycle to cycle, so 22-year and longer cycles are also distinguished. The irregularity of cyclicity manifests itself in the form of extended periods of minimum solar activity with a minimum number of sunspots over several cycles, similar to that observed in the seventeenth century. This period is known as the Maunder Minimum, which had a profound effect on the Earth's climate. Some scientists believe that, during this period, the Sun went through a 70-year period of activity with an almost complete absence of sunspots. Recall that an unusual solar minimum was observed in 2008. It lasted much longer and with a lower number of sunspots than usual. This means that the recurrence of solar activity over tens and hundreds of years is, generally speaking, unstable. In addition, the theory predicts the possibility of the existence of a magnetic instability in the core of the Sun, which can cause fluctuations in activity with a period of tens of thousands of years. […]
The most characteristic and spectacular manifestations of solar activity are solar flares, coronal mass ejections (CMEs) and solar proton events (SPEs). The degree of their activity is closely related to the 11-year solar cycle. These phenomena are accompanied by the ejection of a huge number of high-energy protons and electrons, significantly increasing the energy of the "quieter" particles of the solar wind. They have an enormous influence on the processes of interaction of solar plasma with the Earth and other bodies of the Solar System, including variations in the geomagnetic field, the upper and middle atmosphere, and phenomena on the earth's surface. The state of solar activity determines the space weather that affects our natural environment and life on Earth. […]
Essentially, a flare is an explosion, and this grandiose phenomenon manifests itself as an instantaneous and intense change in brightness in an active region on the surface of the Sun. […] the release of energy from a powerful solar flare can reach […] ⅙ of the energy released by the Sun per second, or 160 billion megatons of TNT. Approximately half of this energy is the kinetic energy of the coronal plasma, and the other half is hard electromagnetic radiation and flows of high-energy charged particles.
“In about 3.5 billion years, the brightness of the Sun will increase by 40%, by which time conditions on Earth will be similar to those on today’s Venus.”
The flash can last about 200 minutes, accompanied by strong changes in the intensity of X-rays and powerful acceleration of electrons and protons, the speed of which approaches the speed of light. Unlike the solar wind, whose particles propagate to the Earth for more than a day, the particles generated during flares reach the Earth in tens of minutes, greatly disturbing space weather. This radiation is extremely dangerous for astronauts, even in near-earth orbits, not to mention interplanetary flights.
Even more grandiose are coronal mass ejections, which are the most powerful phenomenon in the solar system. They arise in the corona in the form of explosions of huge volumes of solar plasma caused by the reconnection of magnetic field lines, resulting in the release of huge energy. Some of them are associated with solar flares or are related to solar prominences erupting from the solar surface and held by magnetic fields. Coronal mass ejections occur periodically and consist of very energetic particles. Plasma clots that form giant plasma bubbles that expand outward are ejected into outer space. They contain billions of tons of matter propagating in the interplanetary medium at a speed of ≈1000 km/s and forming a detached shock wave at the front. Coronal mass ejections are responsible for powerful magnetic storms on Earth. […] Even more than solar flares, CMEs are associated with an influx of high-energy penetrating radiation. […]
The interaction of solar plasma with planets and small bodies has a strong influence on them, primarily on the upper atmosphere and the magnetosphere, intrinsic or induced, depending on whether the planet has a magnetic field. Such an interaction is called solar-planetary (for the Earth-solar-terrestrial) connections, which essentially depend on the phase of the 11-year cycle and other manifestations of solar activity. They lead to changes in the shape and dimensions of the magnetosphere, the occurrence of magnetic storms, variations in the parameters of the upper atmosphere, and an increase in the level of radiation hazard. Thus, the temperature of the Earth's upper atmosphere in the altitude range of 200–1000 km will increase by several times, from ≈400 to ≈1500 K, while the density changes by one or two orders of magnitude. This greatly affects the lifetime of artificial satellites and orbital stations. […]
The most spectacular manifestation of the impact of solar activity on the Earth and other planets with a magnetic field are the auroras observed at high latitudes. On Earth, disturbances on the Sun also lead to disruption of radio communications, impact on high-voltage power lines (blackouts), underground cables and pipelines, the operation of radar stations, and also damage spacecraft electronics.
Signs indicate that unusual phenomena are occurring on the Sun.
Something is happening to the sun, says Michael Snader in investmentwatchblog.com. It began to behave very erratically, and scientists do not know at all how to explain this.
Solar activity seems to be slowing down with each new cycle, and giant "holes" have begun to appear in the sun. At this point, the Sun is approaching the peak of its 11-year cycle, and a growing number of scientists are worried about what the next cycle might bring. If solar activity continues to decline, maybe the solar cycle will eventually disappear once and for all? Is it possible that we are approaching a new ice age? Even worse, could the Sun's strange behavior be a sign that our star is dying? Traditionally, scientists have taught that the sun will never die, but will exist for billions of years. But in recent years, astronomers have observed stars like our Sun that suddenly become very unstable and then die quickly. Is it possible that a similar thing will happen to our Sun?
It is a fact that the current solar cycle has been the weakest in the last 100 years. And many scientists are looking for answers...
Of course, most scientists say that everything will be all right and that there is no cause for concern, but others are not so sure.
For example, Matthew Penn of the National Solar Observatory believes that a new ice age is approaching...
Penn suggested another, more catastrophic option: they could disappear entirely. His team uses the spectra of sunspots to measure their magnetic fields, and his data show a clear trend: magnetic field strengths in sunspots are on the wane.
“If this trend continues, there will be almost no flares in Cycle 25 and we could be in another Maunder low,” Penn says. The first Maunder minimum occurred in the second half of the 17th century. Spots were almost not observed then on the Sun, and this time coincided with the Little Ice Age in Europe.
Another strange phenomenon that astronomers are watching closely is the appearance of giant "holes" in the Sun. More recently, a massive hole that has covered nearly a quarter of the Sun's entire surface has made headlines in the global media...
A space telescope pointed at the sun has seen a giant hole in the sun's atmosphere - a dark spot that covers almost a quarter of our nearest star, spewing solar matter and gas into space.
So-called coronal holes above the Sun's north pole came into view between July 13 and 18 and were observed at the Solar Heliospheric Observatory, or SOHO. NASA has released a video of a "hole" in the sun seen by SOHO satellites.
This event came after another giant "hole" in the Sun was observed, which was seen between May 28 and 31.
Is this what should alarm us?
Some scientists say yes and others say no.
Until the end of the 1930s, astronomers adhered to the version that the history of the solar system would end in complete darkness and cold, and a very unenviable future awaits the Earth. It was believed that The sun just starts to fade away giving off less and less energy.
Because of this, the Earth will turn into an icy world, devoid of light and heat, and the situation on our planet in the future will be even worse than it is now on Pluto. The same opinion about the fate of the Sun and the Earth is shared by the majority of ordinary people, although science has long "written" the scenario for the further development of the solar system.
How could astronomers know what will happen to the Sun and planets in millions and billions of years? This became possible thanks to numerous observations and the creation of several theories based on them, which are confirmed in practice. In particular, there is now a working theory of stellar evolution, thanks to which one can say with confidence what happened to this or that star in the distant past and what awaits it in the future.
Without going into details, the general meaning of this theory boils down to the following: the development, life and death of a star depends on its initial mass and chemical composition. At the same time, stars of the same class (similar in mass, size, chemical composition, luminosity, color, etc.) "live" the same life - they develop and die in the same type.
All this fully applies to our Sun - its future is easily predicted on the basis of observations of millions of stars and according to the developed theory of stellar evolution. According to this theory, our luminary is located approximately halfway through its life cycle, but his "death" will be completely different from what was described at the beginning.
The sun relates to medium sized stars, which are the most in the universe. Such stars are quite stable, and their total lifespan is more than 20 billion years. It is not in vain that it is said about the total duration of the existence of a star - at different stages of its development, the same star is completely different objects with dissimilar characteristics and qualities.
At present, the Sun is at the most stable and longest stage of its life - it began about 4.59 billion years ago, and will end no earlier than in 4 or even 5 billion years. Therefore, they say that the lifetime of our luminary is approximately 10 billion years - after all, then The sun won't be the same anymore, like now.
So, in about 4.5 billion years, the Sun will begin to change. These changes will be caused by a decrease in the amount of hydrogen and an increase in the amount of helium (after all, as is known, thermonuclear reactions of helium synthesis from hydrogen are now observed on the Sun, during which huge energy is released). Our light will gradually increase in size and literally blush. In this case, the core of the star, invisible to the eye, in which the bulk of hydrogen and helium is collected, will shrink and heat up strongly.
But at the stage of the red giant, the Sun will not stop - further its development will continue much faster. So, after 7.8 billion years, conditions will develop in the core of the star under which thermonuclear "burning" of helium will begin, during which oxygen and carbon will be released. This stage is very unstable, the outer shell of the future Sun will expand even more and may even reach the current orbit of the Earth. But what's interesting is that our planet will not burn up in the atmosphere of a star.
The fact is that the Sun, being a red giant, will rapidly “lose weight”, that is, lose your weight This is due to the increased solar wind. And by the time the star reaches the orbit of the Earth, it will become much less massive, which will affect the rotation of all the planets. According to the laws of celestial mechanics, when the mass of the central object decreases, all bodies rotating around it move away, expanding their orbits, that is, the Earth will simply move to a more distant orbit and will not be burned by the Sun. But even this will not save everything that will be on our planet by that time - the temperature increase will be such that even the atmosphere will evaporate into space, and there is no need to even talk about the existence of life.
As it was said, this period of solar life is extremely unstable, but it will not end with an explosion - the mass of the Sun is insufficient for this. Instead of exploding, the core's internal pressure would relatively "quietly" tear off the star's outer shell. This shell, gradually expanding, forms the so-called planetary nebula, which in a few tens of thousands of years will completely dissipate in outer space.
In place of the Sun there will be a small star, comparable in size to the Earth, is a white dwarf (it is not known whether our planet will exist at that time, how lucky it is here). This star shines due to the accumulated heat, and there is enough of it in a white dwarf - according to modern theory, the temperature inside the star reaches several million degrees. The time of existence of such a star, even by astronomical standards, is huge - it can reach hundreds of billions and even trillions of years! Gradually, the white dwarf will cool down, dim, and, finally, must completely cool down and become the "corpse" of the star - dark, cold and motionless.
So an unenviable fate awaits the Earth. First, our planet will become a red-hot desert ball, devoid of water, air and life. And then, if she manages to survive when the shell of the red giant is dropped, she will become a cold satellite of a barely warming and eventually fading white dwarf.
Many people cannot even imagine what will happen if the Sun suddenly takes and disappears. However, this question is not as stupid as it seems. At least, Albert Einstein himself was puzzled by this thought experiment. Based on his calculations, we will try to tell you what will actually happen to the Earth if the Sun goes out.
gravity
Before Einstein asked the question, scientists believed that gravity changed instantly. The disappearance of the Sun would instantly scatter all eight planets into the dark depths of the galaxy. But Einstein proved that the speed of light and the speed of gravity propagate at the same time - which means we will enjoy ordinary life for another eight minutes before we realize the disappearance of the Sun. Our planet will de-orbit and, most likely, will begin to be attracted to some other planet of greater mass, such as Jupiter.
Eternal night
The sun may simply go out. In this case, humanity will not be left in complete darkness. The stars will still shine, the factories will work in the conditions of the polar night - in constant darkness. There will also be no moonlight, because the Moon only reflects the light of the Sun. Most plants will die within a few days - but that's not what should worry us the most. The average temperature of the Earth will fall to -17 degrees Celsius in a week. By the end of the first year, a new ice age will begin. Gradually, the air will turn into a liquid nitrogen ocean, all the water will freeze, the land will freeze over.
remnants of life
Of course, most of the life on Earth will cease to exist. In less than a month, almost all plants will die. Large trees will be able to hold out for several more years, as they have large reserves of nutritious sucrose. However, it will be difficult for them to do this in the face of a global drop in temperature. Perhaps, some deep-sea plants and animals, as well as microorganisms, will be able to live for quite a long time - so, formally, life on Earth will continue.
human survival
What will happen to the person? We may be able to use volcanic heat to heat homes and for industrial purposes, as, for example, the inhabitants of Iceland. They already heat their houses with geothermal energy. However, it is very difficult to imagine life without oxygen produced during plant photosynthesis. Life will also be difficult without plant food, and soon without animal food. Without sunlight, the psyche of people will also be seriously affected, and without ultraviolet radiation, the human body.
Endless journey
If the Sun not only goes out, but also disappears, then the Earth will leave its orbit. Unfortunately, this will not end well for us: the slightest collision with another object will cause huge destruction. At best, if we miraculously manage to avoid collisions, the Earth may well find a new star and enter a new orbit. However, this will happen after a huge amount of time and humanity is unlikely to witness this unlikely event.
This is only a small part of the possible development of events in the event of the disappearance of the Sun, but even this is enough to start truly appreciate our star and be grateful to her for everything she gives us!
