Already three outbreaks in January: solar storms are increasing – that could threaten the earth

Like a gigantic reactor, the sun provides our planet with light and heat. But our central star doesn’t always shine with the same intensity; the activity fluctuates cyclically. During periods of increased activity, solar flares are much more common – as can be seen now: In early January, there were three highest-level solar flares on the scale. None of these eruptions hit Earth, but astronomers see no cause for concern.

When the shock wave from a solar flare hits the Earth’s magnetic field, it’s called a solar storm. If it is very strong, charged particles can even reach the ground and flatten the electrical infrastructure – with catastrophic consequences, experts fear.

In addition to the light and heat radiation that we can observe, there is a steady stream of charged particles from the sun into space, the solar wind. The particles, mainly protons and electrons, heat up so much in the sun’s corona that they overcome gravity and blast into space at speeds of 400 to 800 kilometers per second. In addition, the particle stream also contains particles with a higher energy, but these are much rarer.

The sun loses about a million tons of material every second through the solar wind, but this is negligible in relation to its enormous mass. The continuous stream of particles forms a kind of bubble in the interstellar medium, the heliosphere, which reflects some of the cosmic rays from the galaxy at its edge.

The current also hits the earth, which is well protected from the bombardment by its magnetic field and atmosphere. The particles of the solar wind compress the Earth’s magnetosphere on the side facing the sun; on the other, they extend them into a long tail. The charged particles of the solar wind and cosmic rays are deflected by the Earth’s magnetic field in such a way that they revolve around the Earth in a kind of ring at a distance of about ten Earth radii (70,000 km) – the Van Allen Belt.

The magnetic field lines enter the Earth near the north and south poles. The charged particles of the solar wind and cosmic rays follow these field lines, circling them on small spiral paths, and thus enter the atmosphere near the poles. When they encounter oxygen and nitrogen atoms in the upper layers of the Earth’s atmosphere, they ionize them. The recombination, the elimination of ionization, results in a luminous effect – the aurora, which can sometimes be seen with the naked eye when a stronger stream of particles enters the atmosphere. Strong solar storms can distort the Earth’s magnetic field so much that these effects occur not only at the poles, but also at lower latitudes, such as in Germany or Italy.

The sun is not a completely uniform sphere of gas, but has an atmosphere that is very turbulent. Enormous plasma magnetic field arcs can form in regions of high magnetic field strength in the chromosphere and corona, the outer layers of the sun. These so-called flares, which emit enormous amounts of electromagnetic radiation, occur mainly in zones of the solar surface where sunspots appear. They can lead to a kind of magnetic short circuit: the magnetic field lines, which otherwise enclose the plasma in their arcs, break off locally and recombine. Huge amounts of plasma can be flung into space.

Based on their X-ray energy, flares are logarithmically classified into classes A, B, C, M, and X, with each class divided into 10 levels (except X). The largest solar flare ever recorded occurred in September 2003 and was classified as X45. Some astronomers believe the sun can also produce so-called superflares that are up to a million times more powerful. Such superflares have already been observed in other stars.

During solar flares, three processes take place that can be distinguished:

A solar storm is the name given to the phenomena that occur on Earth when it is hit by the radiation and particles of a solar flare. They consist of a disturbance of the Earth’s magnetic field, which lasts about 24 to 36 hours, but can also last several days in individual cases. When the shock front of electrically charged particles hits the magnetosphere, the Earth’s magnetic field is weakened; it reaches its minimum after about 12 hours.

Usually, a distinction is made between three phases of a solar storm:

The X-ray flash from a solar flare can cause radio interference on Earth. There are also radiation effects caused by high energy particles and geomagnetic effects caused by the plasma cloud.

When a solar storm crushes the Earth’s magnetic field, the energetically charged particles can penetrate far into the Earth’s atmosphere and even reach the ground. Auroras can therefore be seen at lower latitudes. However, the global deformation of the geomagnetic field can cause strong currents in power lines – formerly telegraph lines – and thus cause considerable damage. For example, transformers can break down and large parts of the electricity grid can fail as a result.

This became evident in 1859 when the most powerful solar storm to date was observed, the so-called Carrington event: At higher latitudes in North America and Europe, strong currents shot through the telegraph lines, the resulting sparks set telegraph paper on fire, and wildfires broke out in Sweden from. The telegraph network was greatly affected.

For current infrastructure, which is much more dependent on electricity, a solar storm of this size would be much more devastating. How far-reaching the consequences can be is shown by the violent solar storm that disrupted the radar systems of the American missile system in May 1967 and almost unleashed a nuclear war.

Due to their ionizing effect, the charged particles can electrically charge the circuits of computer chips. This can cause the chip to malfunction. This danger is, of course, much greater for orbiting satellites; their computers must therefore be specially secured. Satellites are already heavily exposed to the effects of a solar storm; their solar cells, which are used to provide energy, can be permanently damaged. The high-energy radiation also heats up the outer layers of the Earth’s atmosphere, causing them to expand. This can slow down low-Earth satellites.

There may also be problems with the GPS service. Because the Earth’s atmosphere is more ionized than usual, especially at higher latitudes around 100 to 150 kilometers above sea level, the communication signals from the GPS satellites, which must traverse this layer, are slightly delayed. As a result, GPS devices can calculate their location incorrectly.

Solar flares are more common when the sun is in a period of increased activity. This corresponds to the number of dark sunspots on the visible surface: they are particularly numerous when the sun is particularly active. Solar flares are then not only more numerous, but also more intense. However, strong solar flares can occasionally occur during minimal activity.

The Sun’s activity is cyclical: Violent plasma currents sweep over years of magnetic structures on the surface, often associated with sunspots, from the equator to the poles. There the plasma descends and flows back to the equator. A solar cycle lasts about eleven years. The sun is currently in cycle number 25; it is a more active phase than before. The maximum of the current cycle should be reached in July 2025 – for this peak, NASA and the US weather agency NOAA expect 115 sunspots per month, as reported by the “Washington Post”. There are, of course, researchers who predict twice as many sunspots – and the preliminary results speak more in their favour.

In any case, the number of sunspots and solar flares will increase in the coming months. The X-class flares, seen in early January, came from two sets of sunspots that will move closer to the center of the solar disk in the near future. This means that eruptions resulting from it are directed towards Earth. The risk of a solar storm is therefore greater than before. However, solar flares cannot be predicted by current means – but at least there is a short warning period if one is observed. There is usually one to two days between the occurrence of an outburst on the sun and the arrival of the plasma cloud on Earth.

It is currently not possible to predict a solar flare, as the exact mechanisms of this phenomenon have not yet been elucidated. Forecasts are therefore based on empirical methods: the researchers assume that sunspots that have caused outbursts so far will also produce more. However, the method cannot predict which group of sunspots will become active and when their activity will stop.

However, we are not completely at the mercy of the activities of the sun. Several space probes and satellites are constantly observing our central star from space – such as the Earth satellites GOES and the space probes SoHO (Solar and Heliospheric Observatory), STEREO and SDO (Solar Dynamics Observatory). You see the first signs of a solar flare. With data from other probes, the propagation direction and speed of the solar storm can then be calculated. For example, the Space Weather Prediction Center (SWPC) of the US National Oceanic and Atmospheric Administration (NOAA) makes these kinds of predictions.