The number of sunspots is currently higher than it has been for over 20 years. Since their frequency is related to the Sun’s activity, many solar storms then occur – and depending on their direction, they can also become explosive for the Earth.
More solar storms are likely to occur in the coming years, Sami Solanki, director at the Max Planck Institute for Solar System Research (MPS), told dpa.
In the long term, in the middle range
Sunspots occur more frequently in a roughly eleven-year cycle. Currently, the Sun is in solar cycle 25, and according to data from the U.S. National Oceanic and Atmospheric Administration (NOAA), the number of sunspots has already exceeded the maximum of the previous cycle. “However, it must also be emphasized that cycle 24 was fragile,” Solanki said. He added that the number of sunspots is in the middle range when viewed across all solar cycles.
A greater quantity of sunspots, in Solanki’s view, suggests a stronger and more active magnetic field on the Sun. The researcher said there are more mass ejections, in which some of the Sun’s atmosphere is thrown into interplanetary space.
Colder spots on the Sun’s surface
The German Aerospace Centre (DLR) explains the formation of sunspots this way: Hot matter from the Sun’s interior permanently swirls to the surface. This process can be hindered by local amplifications of the Sun’s magnetic field. As a result, slightly colder spots appear on the Sun’s surface, which become visible as sunspots.
“A sunspot consists of a very strong magnetic field. It’s several thousand times stronger than the Earth’s magnetic field,” Solanki explained. “That means there’s a lot less energy coming to the surface there, and a lot less can be radiated. And that’s why the spots appear dark.”
Consequences on Earth
The more sunspots experts discover the more likely solar flares are. According to the European Space Agency (ESA), tens of billions of tons of high-energy particles can be hurled into space in the process. Within hours, they can also reach the Earth, about 150 million kilometres away. The Earth’s protective shield – the magnetosphere – “is pulled apart like a soap bubble and can, so to speak, rupture.” The particles can then enter the magnetic field.
That could lead to “beautiful things like auroras” but also satellite damage, Solanki said. The collapse of a power grid is also possible, he said. “It’s happened before, mostly at slightly higher latitudes. But we haven’t had a massive solar storm in 150 years. So it can get worse,” the researcher stressed. Massive eruptions, however, are rare, he said. However, even with a few spots, “only a single huge spot” on the Sun is enough, which could also cause a more dangerous eruption with great magnetic energy.
little impact on the climate of Earth
On the other hand, the impact of solar storms on Earth’s climate is small: “The brightness of the Sun varies with the number of sunspots, and there are several indications that such variations have a minor impact on climate,” Solanki said. It is crucial to stress, though, that these brightness variations have not had a major impact on the Earth’s temperature rising quickly over the previous 50 years.
To improve forecasting for space weather in the future, ESA is currently working on a satellite that Solanki said will launch in a few years. It will measure the Sun’s magnetic field.
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