A new solar cycle has begun, signalling a period of increased solar activity, according to an international panel of scientists.
The Solar Cycle 25 Prediction Panel, which includes expertise from the University of Birmingham, is responsible for identifying the start and end of each cycle, or period of solar activity, and making predictions about its progression. These are important because increased solar activity – or space weather – can have an impact on our lives and technology on Earth, as well as on astronauts in space.
According to panel members, the Cycle 25 actually began in December 2019, when solar activity was at its lowest point, or solar minimum. Because our sun is so variable it can take several months for scientists to be certain that a new cycle has begun. Cycles last, on average, for 11 years, with Cycle 25’s peak expected in 2025.
Dr Rachel Howe, in the School of Physics and Astronomy, was a member of the prediction panel. She says: “Solar activity has an impact on our daily lives because big solar storms can damage power grids, disrupt satellites, and expose astronauts to radiation, so it's important to study it so that we can forecast those events.
“Although a solar cycle is usually roughly 11 years long, both the length and the strength of the cycle can vary. The Sun's ever-changing magnetic fields cause dark sunspots on the solar surface, with more spots at solar maximum and few or none at solar minimum. Especially when activity is high, the fields can erupt into space, flinging out material that can reach the Earth's orbit and interact with its magnetic field to cause phenomena such as the aurora borealis, or northern lights'.”
Dr Howe’s expertise is in helioseismology, using sound waves in the Sun to understand what is happening deep inside its core. A particular focus is on understanding how the different parts of the sun rotate at different speeds, and how that changes over the course of a solar cycle. These patterns, along with patterns of sunspot activity, can be used to help predict when the next cycle is due to start.
“With the previous sunspot cycle ending in late 2008, Cycle 25 has arrived right on schedule,” she explains. “ But the minimum before the current one was both unusually deep -- the Sun was very, very ``quiet'' in 2008 and 2009, with very few sunspots or other signs of activity such as solar flares -- and unusually long, so that Cycle 23 didn't end for about 12.5 years after Cycle 22. So it's important to know that we don't seem to be heading into another epoch of sustained low activity – which would mean that we would see few solar storms or sunspots but potentially be more exposed to cosmic rays from outside the solar system. Instead, we know that we do need to plan for the possibility of solar storms in the coming years.