30.01.2024

NOAA's Space Weather Prediction Center released a revised prediction for solar activity during Solar Cycle 25. The new Experimental Solar Cycle Prediction issued on Oct. 25 concludes that solar activity will increase more quickly and peak at a higher level than previously predicted The updated prediction calls for Solar Cycle 25 to peak between January and October of 2024, with a maximum sunspot number between 137 and 173. (NOAA)

Much like the Earth, our Sun is a dynamic body with a complex - and sometimes violent - weather system. Solar storms eject highly energetic radiation that can impact our planet, forming strong auroras and disrupting power grids, electronics, and satellites.

The scientific study of space weather attempts to understand, track, and forecast this solar activity, which peaks with the solar maximum every 11 years. The current solar cycle is predicted to peak in 2024. So, what might this mean for you?

Solar power to the max
From Earth, the Sun appears relatively constant. It rises and sets, providing a steady stream of energy that sustains almost all life on our planet. But when viewed in other wavelengths, such as radio or X-rays, it becomes clear the Sun is changing all the time.

Electrically conductive plasma churns and flows beneath the surface, forming powerful bundles of magnetic fields. When these rise to the surface, they create sunspots - dark patches of cooler plasma. Sunspots are an important tool in tracking the likelihood of a major space weather event.

Dr Mark Cheung is CSIRO's Science Director for Space and Astronomy, and explained "magnetic fields within sunspots are comparable in strength to an MRI machine, but the size of entire planets.

When sunspots collide, it stresses the magnetic bundles until they snap. This lead to solar flares and eruptions. Ultraviolet and X-ray radiation from flares puff up our outer atmosphere, reaching Earth in under nine minutes. This radiation increases drag on satellites and can also disturb the ionosphere, causing radio blackouts and leading to strong auroras.

Heavier particles, such as protons, take around 15 minutes to reach the Earth. These 'Solar Energetic Particles' can damage the electronics of satellites in orbit. They can even increase the radiation dose experienced by passengers and crew on flights near the poles.

In more extreme cases, entire bundles of magnetic plasma - a coronal mass ejection (CME) - can be flung toward Earth. CMEs travel at thousands of kilometres per second. If aligned just right with the Earth's magnetosphere, they can have an enormous impact.

"The bundles of magnetic fields and charged materials can hit us like ringing a bell, intensely shaking Earth's magnetosphere," Mark said.

"Regional power blackouts could occur, satellites could sustain heavy damage, and oil pipelines could experience faster corrosion."

Sunspot numbers wax and wane over an 11-year cycle, with the greatest number appearing during solar maximum. More sunspots mean more collisions, leading to stronger space weather.

Identify, track, predict
Flares are rated on a scale from A, B, C, M, to X - with X being the strongest.

An X2.8 flare in mid-December 2023 was quickly eclipsed on 1 January 2024, with the same location birthing an X5.0 flare. This is the strongest flare seen since 2017.

"That was by far the biggest fireworks in the Solar System - a good way to ring in 2024," Mark said.

While typically only visible in the far north and far south of the globe, stronger flares and CMEs can make auroras visible closer to the equator. And with solar activity increasing as we head towards the maximum, skywatchers can expect to see more auroras. Keep looking up!

The science of predicting individual flare events is advancing rapidly, thanks to a raft of terrestrial and space-based observatories, along with machine learning for space weather forecasting.

A coordinated effort
The Bureau of Meteorology is the Australian Government's lead agency in space weather and operates the Australian Space Weather Forecasting Centre.

Through the Forecasting Centre, the Bureau provides space weather information and warning services to potentially affected industries, government agencies, including the Department of Defence, Department of Home Affairs and National Situation Room, and the community.

Its capability is focused on severe to extreme events that may threaten critical infrastructure, including radio communications, satellite operations, GPS navigation, mineral exploration, pipeline protection and electricity supply networks. The Bureau works closely with the space industry and operations that can be affected by space weather events - such as the aviation, energy, defence and telecommunication industries - to tailor forecasts and warnings to their specific needs.

The Bureau's Space Weather Observation Network spans the Australasian region and Antarctica, and includes the Learmonth Solar Observatory, a network of magnetometers, riometers and ionosondes to provide continuous, real-time observations, and global navigation satellite system total electron content scintillation monitors. The Bureau also exchanges data with Australian and international organisations.

Accurate and timely warnings are important to provide airlines time to re-route planes, satellite operators time to tweak their orbits, and communities the opportunity to prepare for power or radio blackouts.

Quelle: SD