The Sun is waking up: what are the real risks to Earth

The eruption caused a shortwave radio blackout over the Atlantic Ocean. On July 3, our star emitted an X-class glow, the most powerful since September 2017.

The Sun appears to have awakened after a period of quiet during its 11-year cycle. On July 3, our star emitted the first X-class flare of solar cycle 25 - it was the most powerful glow we've seen since September 2017. X-class flares are among the strongest solar flares with the most surprising being recorded in November 2003. This new flare, while not as intense, still produced an X-ray pulse that hit the upper atmosphere and managed to cause a shortwave radio blackout over the Atlantic Ocean.

The Sun's X-class flare

The solar flare, along with an increase in coronal cycles of plasma rising from the Sun's surface, show that our star's cycle is becoming more active. The solar cycle is based on the Sun's magnetic field, which reverses every 11 years, meaning the north and south magnetic poles switch places. It's not yet clear what drives these cycles, but the poles change when the magnetic field is weakest, a condition also known as solar minimum.

Because the Sun's magnetic field controls its activity, namely sunspots, flares and coronal mass ejections, this phase of the cycle manifests as a period of minimal activity. Once the poles have switched, the magnetic field strengthens and solar activity rises to a maximum before subsiding for the next polar break. The most recent solar minimum occurred in December 2019, so over the next few months and years, we should expect to see the Sun become more active, with an estimated maximum peak around July 2025.

In reality, though, not all solar maxima are the same, and we don't yet know if we'll have a weak or powerful cycle. The average sunspot count comes in at a high of 179. Solar cycle 24 peaked at 114. Nasa and Noaa have predicted that solar cycle 25 will be similar, peaking at 115 sunspots, although other scientists have speculated just the opposite: that one of the strongest solar maxima ever recorded will occur.

What are the risks to Earth?

For Earth's living things, flares do not create radiation hazards because our atmosphere protects us. Problems could occur, however, for more powerful flares, such as the one on July 3, and weaker M-class flares, which could disrupt their activity. This means that radio communications and navigation systems could suffer blackouts. Electricity grids could also go down, but that's an event that happens very rarely.

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Stefania Bernardini