After the invention of the telescope, astronomers Galileo Galilei, Thomas Herriot, Christoph Scheiner and Jan Fabricius independently discovered that spots appear on the disk of the Sun. However, it took almost 250 years to understand that the behavior of the Sun follows a certain schedule with a period of 11 years. The eleven-year periodicity of solar activity was accidentally discovered in the 19th century by the German pharmacist Heinrich Schwabe. He was interested in astronomy and, using an amateur telescope, sought to discover a hypothetical minor planet within the orbit of Mercury. He never found the planet, but thanks to systematic observations he discovered solar activity cycles. Such sunspot observations are now conducted twice daily throughout the year by observatories around the world, and predicting the 11-year solar cycle is of paramount importance in many areas of human activity in space and on Earth.

Space weather

At the beginning of the 20th century, the outstanding Russian scientist Alexander Chizhevsky proposed the idea of ​​space weather and laid the foundation for the emergence of a new branch of science that studies solar-terrestrial relationships. He said that the Earth is constantly in the arms of the Sun. And the mood of the Sun is transmitted to the Earth through these embraces. From the solar corona, the atmosphere of the Sun, the solar wind constantly flows, a stream of charged particles that blows over the Earth and other planets of the solar system. The solar wind carries the energy of the Sun, stretches and carries with it the solar magnetic field into outer space. As a result, the entire solar system is filled with solar wind and the solar magnetic field. And since the Sun rotates, the magnetic field in interplanetary space takes the form of wavy spiral folds, like a multi-layered ballerina’s skirt. And the Earth and all the planets of the solar system live in these folds.

Solar and Heliospheric Observatory The image illustrates solar activity over 11 years, from a minimum in 1996 to a maximum in 2001 until a return to minimum in 2006

One way or another, people have to take into account forecasts of active events on the Sun in their daily plans. Putting a satellite into safe mode during active solar events can prevent disruption to the satellite's solar arrays and key systems. Space weather is a threat to astronauts in outer space exposed to significant radiation exposure above the threshold for radiation sickness. Active events on the Sun can cause interference in the propagation of radio signals. Space weather affects the radiation doses received by pilots and passengers, especially during transpolar flights. Timely forecasting of space weather is of great importance for aviation and the protection of a number of ground-based technical systems, for human space flight, and launches of scientific and commercial satellites.

The solar cycle begins with the emergence of sunspots at the poles; as the cycle progresses, more and more sunspots appear, which move from the poles to the equator of the Sun. At the minimum of solar activity, when there are practically no spots on the Sun, the Sun's magnetic field looks like an ordinary magnet, with circular magnetic lines and two poles. Since the equator of the Sun rotates faster than the poles, during the rotation of the Sun the magnetic field seems to become entangled, like a ball of thread. As solar activity approaches its maximum, the familiar magnetic field with two poles turns into many local magnetic fields on the surface of the Sun, entangled loops are put forward in the solar atmosphere that contain solar matter, and they can be ejected in the form of flares and coronal mass ejections and reach Earth. Consequently, at the maximum of solar activity, the number of active events on the Sun increases significantly. On the other hand, at its peak, the Sun's magnetic field is so strong that it sweeps galactic cosmic rays out of our solar system, which pose a great danger to technological systems in space. Every 11 years, the poles of the Sun change places, the southern one appears in the place of the northern one, and vice versa. This is a complex process that is not fully understood, and the solar dynamo model is one of the most difficult nonlinear problems in mathematical physics.

Solar cycle forecast

Each solar cycle is assigned a number for convenience, for example, we are now approaching a minimum of 24 cycles of solar activity. The task of scientists is to predict the strength of the next 25 cycle of solar activity as early as possible. Scientists from Skoltech, Karl-Franz-Universität Graz and the Royal Observatory of Belgium have developed a method that makes it possible to predict the strength of the next 11-ribbon cycle very early, namely at the maximum stage of the current solar cycle. This means that the current solar cycle, at its peak, when the solar magnetic field is reversing, already carries knowledge about the strength of the future 11-year cycle. These discoveries may help to study the mechanism of action of the solar dynamo. The analysis showed that short-term variations in solar activity during the falling phase of the cycle are related to the strength of the next cycle. Sudden jumps in activity in the falling phase and a slowdown in the rate of decline in the relative number of sunspots indicate the presence of activity, which manifests itself in a greater amplitude of the next cycle compared to the current cycle. This study proposes a new and robust method to quantify short-term solar activity variations already at the maximum stage of the current solar cycle, at the beginning of the decline phase, and generates a meaningful indicator for predicting the strength of the next cycle.

The forecast predicts that future solar activity will be low and the strength of the next solar cycle 25 will be even less than the strength of the current solar cycle 24. The results of the study were published in The Astrophysical Journal.

“Space weather is the science of the future, something that unites us all, makes our lives better, and allows us to take care of our planet. This is the next step in space exploration. And no matter what storms rage, we wish you good space weather!” — says the first author of the study, Skoltech professor Tatyana Podladchikova.

Material provided by the press service of the Skolkovo Institute of Science and Technology (

For eleven whole days on the Sun, contrary to the well-known saying, there is not a single spot. This means that our star is entering a period of minimal activity and magnetic storms and X-ray flares will become rare over the next year. We asked Sergei Bogachev, an employee of the Laboratory of X-ray Solar Astronomy of the Lebedev Physical Institute, Doctor of Physical and Mathematical Sciences, to talk about what happens to the Sun when its activity increases again and what explains these declines and rises.

There are no sunspots on the sun today

The average monthly Wolf number on the Sun - an index used by scientists to measure the number of sunspots - dropped below 10 in the first three months of 2018. Before that, in 2017 it remained at the level of 10–40, and a year earlier in some months it reached 60. At the same time Solar flares have almost ceased to occur on the Sun, and along with them the number of magnetic storms on Earth tends to zero. All this indicates that our star is confidently moving towards the next minimum of solar activity - a state in which it finds itself approximately every 11 years.

The very concept of the solar cycle (and by it is meant the periodic change of maxima and minima of solar activity) is fundamental for the physics of the Sun. For more than 260 years, since 1749, scientists have been monitoring the Sun on a daily basis and carefully recording the position of sunspots and, of course, their number. And, accordingly, for more than 260 years, periodic changes have been observed on these curves, somewhat similar to the beating of a pulse.

Each such “beat of the solar heart” is assigned a number, and a total of 24 such beats have been observed since the beginning of observations. Accordingly, this is exactly how many solar cycles are still familiar to humanity. How many of them were there in total, whether they exist all the time as long as the Sun exists, or appear sporadically, whether their amplitude and duration change and what duration, for example, the solar cycle had during the time of the dinosaurs - there is no answer to all these questions, as well as to the question , whether the activity cycle is characteristic of all solar-type stars or exists only on some of them, and if it does, then whether two stars with the same radius and mass will have the same cycle period. We don't know that either.

Thus, the solar cycle is one of the most interesting solar mysteries, and although we know quite a lot about its nature, many of its fundamental principles are still a mystery to us.

Graph of solar activity, measured by the number of sunspots, over the entire history of observations

The solar cycle is closely related to the presence of a so-called toroidal magnetic field in the Sun. Unlike the earth's magnetic field, which has the form of a magnet with two poles - north and south, the lines of which are directed from top to bottom, the Sun has a special type of field that is absent (or indistinguishable) on Earth - these are two magnetic rings with horizontal lines that encircle Sun. One is located in the northern hemisphere of the Sun, and the second in the southern, approximately symmetrically, that is, at the same distance from the equator.

The main lines of the toroidal field lie under the surface of the Sun, but some lines can float to the surface. It is in these places, where the magnetic tubes of the toroidal field pierce the solar surface, that sunspots appear. Thus, the number of sunspots in a sense reflects the power (or more precisely, the flux) of the toroidal magnetic field on the Sun. The stronger this field, the larger the spots, the greater their number.

Accordingly, from the fact that once every 11 years spots on the Sun disappear, we can make the assumption that once every 11 years the toroidal field disappears on the Sun. That is how it is. And actually this - the periodic appearance and disappearance of the solar toroidal field with a period of 11 years - is the cause of the solar cycle. The spots and their number are only indirect signs of this process.

Why is the solar cycle measured by the number of sunspots, and not by the strength of the magnetic field? Well, at least because in 1749, of course, they could not observe the magnetic field on the Sun. The magnetic field of the Sun was discovered only at the beginning of the 20th century by the American astronomer George Hale, the inventor of the spectroheliograph - an instrument capable of measuring with high accuracy the profiles of lines in the solar spectrum, including observing their splitting under the influence of the Zeeman effect. Actually, this was not only the first measurement of the Sun’s field, but in general the first detection of a magnetic field in an extraterrestrial object. So all that remained for astronomers of the 18th-19th centuries was to observe sunspots, and they had no way to even guess about their connection with the magnetic field.

But why then do spots continue to be counted in our days, when multi-wave astronomy has been developed, including observations from space, which, of course, provide much more accurate information about the solar cycle than simply counting the Wolf number? The reason is very simple. Whatever modern cycle parameter you measure and no matter how accurate it is, this figure cannot be compared with data from the 18th, 19th, and most of the 20th centuries. You simply won't realize how strong or weak your cycle is.

Last cycle of solar activity

SILSO data/image, Royal Observatory of Belgium, Brussels

The only way to make such a comparison is to count the number of spots, using exactly the same method and exactly the same formula as 200 years ago. Although it is possible that in 500 years, when significant series of new data on the number of flares and radio emission fluxes have been accumulated, the series of sunspot numbers will finally lose relevance and will remain only as part of the history of astronomy. So far this is not the case.

Knowledge of the nature of the solar cycle allows us to make some predictions about the number and location of sunspots and even accurately determine the moment when a new solar cycle begins. The last statement may seem dubious, since in a situation where the number of spots has decreased to almost zero, it seems impossible to confidently assert that the spot that was there yesterday belonged to the previous cycle, and the spot today is already part of the new cycle. Nevertheless, there is such a way, and it is connected precisely with knowledge of the nature of the cycle.

Since sunspots appear in those places where the surface of the Sun is pierced by the lines of the toroidal magnetic field, each spot can be assigned a certain magnetic polarity - simply in the direction of the magnetic field. The spot can be “northern” or “southern”. Moreover, since the magnetic field tube must pierce the surface of the Sun in two places, the spots should preferentially form in pairs. In this case, the spot formed in the place where the lines of the toroidal field leave the surface will have northern polarity, and the paired spot formed where the lines go back will have southern polarity.

Since the toroidal field encircles the Sun like a ring and is directed horizontally, pairs of sunspots are oriented predominantly horizontally on the solar disk, that is, they are located at the same latitude, but one is in front of the other. And since the direction of the field lines in all spots will be the same (they are formed by one magnetic ring), then the polarities of all spots will be oriented the same way. For example, the first, leading, spot in all pairs will be northern, and the second, lagging, southern.

Structure of magnetic fields in the sunspot region

This pattern will be maintained as long as this field ring exists, that is, all 11 years. In the other hemisphere of the Sun, where the symmetrical second ring of the field is located, the polarities will also remain the same for all 11 years, but will have the opposite direction - the first spots will be, on the contrary, southern, and the second - northern.

What happens when the solar cycle changes? And a rather surprising thing happens, called polarity reversal. The north and south magnetic poles of the Sun change places, and with them the direction of the toroidal magnetic field also changes. First, this field passes through zero, this is what is called the solar minimum, and then begins to recover, but in a different direction. If in the previous cycle the front spots in some hemisphere of the Sun had northern polarity, then in the new cycle they will already have southern polarity. This makes it possible to distinguish the spots of neighboring cycles from each other and confidently record the moment when a new cycle begins.

If we return to the events on the Sun right now, we are observing the process of dying of the toroidal field of the 24th solar cycle. Remnants of this field still exist below the surface and even sometimes float to the top (we see isolated faint spots these days), but overall these are the last traces of the dying “sunny summer”, like the last few warm days in November. There is no doubt that in the coming months this field will finally die and the solar cycle will reach another minimum.

Scientists from the Laboratory of X-ray Solar Astronomy of the Physical Institute named after. P.N. Lebedev RAS (FIAN) detected on the star a region with a magnetic field of a different direction, different from the one that has existed for the last 11 years. According to astrophysicists, this indicates the approach of a new cycle of solar activity. The laboratory's website reports this.

Possible magnetic fields of the new 25th solar cycle
The photo was taken by the HMI telescope on the SDO satellite on November 8, 2018.

The activity of the Sun changes with a certain periodicity under the influence of the magnetic field of the star. These periods are called solar cycles. The change in the Sun's magnetic field is associated with a dynamo mechanism, or solar dynamo. During the cycle, the magnetic field lines change their directions: at first they are located along the meridians, and when the maximum activity is reached, they are replaced by those directed along the parallels. During this period, the number of spots on the star reaches its maximum. Then the lines return to the “vertical” position, but in the opposite direction to the initial one. The entire process takes about 11 years, which is why it is called the 11-year solar cycle. And since at the minimum of the solar cycle the global magnetic field of the star changes its direction, for it to return to its initial position it is necessary for a 22-year cycle to pass.

In Russia, the leading center for studying solar activity is the Laboratory of X-ray Solar Astronomy. Its employees monitor and analyze solar activity using the TESIS space telescope complex developed in the laboratory. This equipment is installed on board the Russian satellite CORONAS-FOTON, launched in 2009 from the Plesetsk cosmodrome. Thanks to TESIS, scientists have obtained more than half a million new images of the solar corona, solar flares, coronal mass ejections and other phenomena.

Thus, on November 8, using TESIS, scientists registered a region of a magnetic field of a different direction on the Sun. It appeared far from the equator and lasted for about a day. Then, on November 17, at approximately the same latitudes, a new magnetic flux appeared in the same direction as on November 8. Now it is almost destroyed, but its traces are still visible on the disk of the Sun.

Astrophysicists associate the appearance of these areas with the imminent start of a new solar cycle. Magnetic fields on the Sun are formed at great depths and “float” to the surface very slowly. As a rule, the “first swallows” of a new cycle are such small magnetic islands that managed to break through the thickness of solar plasma more than 200,000 km deep.

After this, events may begin to develop according to different scenarios. A slow increase in activity over two to three years is possible. But there may also be a sharp rise over six months to a year, after which a series of flares will begin - colossal emissions of energy and an increase in the level of X-ray and ultraviolet radiation from the Sun. When a stream of high-energy particles reaches Earth, it can cause magnetic storms. They, in turn, can lead to overloads in electrical systems and disrupt radio communications.

The graphs on this page display the dynamics of solar activity during the current solar cycle. The tables are updated every month by SWPC with the latest ISES forecasts. Observed values ​​are temporary values ​​that are replaced by final data when available. All graphics on this page can be exported as JPG, PNG, PDF or SVG files. Each data set can be turned on or off by clicking on the corresponding description below each graph.

Number of C, M and X-class solar flares per year

This graph shows the number of C, M, and X-class solar flares that occurred during the year you specified. This gives an idea of ​​the number of solar flares relative to the number of sunspots. So this is another way to see how the solar cycle evolves over time. This data comes from NOAA's SWPC and is updated daily.

The graph below shows the number of C, M and X-class solar flares that occurred during the last month along with the number of sunspots of each day. This gives an idea of ​​solar activity over the past month. This data comes from NOAA's SWPC and is updated daily.

Number of perfect days in a year

During periods of low solar activity, sunspots may be completely absent on the surface of the Sun; this state of the Sun is considered impeccable. This often happens during solar minimum. The graph shows the number of days during a given year that there were no sunspots on the surface of the Sun.

Number of days per year when geomagnetic storms were observed

This graph shows the number of days per year when geomagnetic storms were observed and how strong these storms were. This gives an idea of ​​what years there were many geomagnetic storms and the dynamics of their intensity.