The number of sunspots observed in June exceeded 160, marking the highest monthly count in over 20 years. This data confirms that the current solar cycle, known as the 25th cycle, is accelerating at a much faster pace than previously predicted by NASA and the U.S. National Oceanic and Atmospheric Administration (NOAA). Consequently, scientists are now expressing concerns about the likelihood of severe space weather events in the coming months and years.
Initial forecasts from space agencies projected a maximum monthly sunspot count of around 125 during the peak of the 25th solar cycle. However, recent observations indicate that the sun is on track to reach nearly 200 sunspots per month, surpassing expectations. Some experts even speculate that this peak may occur within a year. Solar physicist Keith Strong shared the exciting news on Twitter, stating that the June 2023 sunspot number of 163.4 is the highest average value recorded in over two decades, since September 2002.
On July 2, one of these sunspots unleashed a powerful solar flare, an energetic burst of light. This event caused a temporary radio blackout across the western United States and the Pacific Ocean, as reported by Spaceweather.com. With the solar cycle approaching its maximum, similar occurrences may become more frequent in the near future.
Contrary to the initial forecasts by NASA and NOAA, this solar maximum is expected to be quite active. An increase in sunspot activity not only leads to more solar flares but also enhances the occurrence of coronal mass ejections (CMEs), which are powerful eruptions of charged particles forming solar wind. This heightened activity poses a risk of adverse space weather conditions on Earth. Intense solar wind bursts can penetrate Earth's magnetic field, energizing particles in the atmosphere and giving rise to captivating aurora displays. However, they can also cause significant disruptions to power grids and satellites orbiting the planet.
Tom Berger, a solar physicist and director of the Space Weather Technology Center at the University of Colorado, Boulder, mentioned in a previous interview with Space.com that after a major solar storm in October 2003, satellite operators experienced a loss of communication with hundreds of spacecraft for several days. This occurred due to increased gas density in the upper layers of the atmosphere, specifically within the low Earth orbit region where many satellites, including the International Space Station, are positioned.
As the thin gas in this region interacts with solar wind, the atmosphere expands, resulting in satellites experiencing higher drag or resistance than during periods of calm space weather.
"In the most severe storms, the orbital trajectory errors become so significant that the catalog of orbital objects becomes invalidated," Berger explained. "The objects can be several tens of kilometers away from their last radar-located positions. They are essentially lost, and the only solution is to locate them again using radar."
Experts are concerned that the growing number of satellites and space debris fragments in low Earth orbit since the last major solar storm could lead to orbital chaos lasting for weeks. During this period, the risk of hazardous collisions with space debris fragments would be exceptionally high, posing further risks to satellite operators.
Several operators have already encountered difficulties due to space weather. SpaceX, for instance, lost a group of 40 new Starlink satellites during a launch in February 2022, underestimating the impact of a seemingly mild solar storm. The satellites burned up in Earth's atmosphere when they couldn't achieve the expected orbit due to unexpected drag. Similarly, the European Space Agency (ESA) reported issues last year when its three Swarm satellites, which study the planet's magnetic field, started descending at an unprecedented rate. Operators had to utilize the satellites' thrusters to prevent them from falling into Earth's denser gas.
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During extreme events, charged solar particles can damage spacecraft electronics, disrupt GPS signals, and even cause power grid failures on Earth. The most intense solar storm on record, known as the Carrington Event in 1859, resulted in sparks flying off telegraph machines, setting documents ablaze. The disruption to telegraph services in Europe and North America lasted for several days.
NASA solar physics research scientist Robert Leamon stated in a previous interview with Space.com that the most severe solar storms tend to occur during the declining phase of odd-numbered solar cycles. Therefore, challenging years may lie ahead for spacecraft operators.
"Since Cycle 25 is an odd cycle, we might expect the most potent events to occur after the maximum, in 2025 and 2026," Leamon explained. "This is due to the reversal of the sun's poles every 11 years. The alignment of the sun's pole with Earth's poles causes the most damage and the strongest coupling between the solar wind and Earth's magnetic field."
In the meantime, space weather forecasters are continuously monitoring the sunspot responsible for the recent solar flare, along with several other sunspots developing on the sun's surface. Forecasters warn that more solar activity and fireworks are possible in the week ahead. Although no coronal mass ejection is currently directed towards Earth, the UK space weather forecaster Met Office stated that auroras may receive a boost from high-speed solar wind streaming through a hole in the sun's magnetic field.