Summer on the Sun: How the solar cycle impacts Earth

The Sun doesn’t just power Earth’s seasons – it has its own. Most of us think of seasons as things we feel: cold mornings, long days, or trees shedding their leaves. That’s Earth’s tilt in action as it orbits the Sun.

The Sun has its own rhythm. It doesn’t shift with seasons like Earth, but with energy – and right now, it’s fired up.

This phase is called the solar maximum – the Sun’s equivalent of summer. Magnetic activity surges, and its energy doesn’t stay confined to space. It reaches Earth, lighting up the skies with auroras or interfering with our technology.

The Sun’s magnetic flip

Every 11 years or so, the Sun’s magnetic field flips. North becomes south, and the Sun gets restless. During this time, we see more sunspots, solar flares, and more massive eruptions known as coronal mass ejections, or CMEs.

When those energy bursts reach Earth, they can light up the poles with auroras. Lately, these displays have been especially intense.

“Spectacular displays of aurora in the night sky for the last year or so are a classic product of the maximum solar activity phase our sun is experiencing during 2024–2025,” noted Dr. Deepak Chahal from Macquarie University, who led recent research into stellar magnetic cycles.

We’re currently in Solar Cycle 25, which kicked off in 2019. Researchers believe it may have peaked already in 2024 – explaining the recent widespread auroras.

Solar summer on Earth

Unlike a storm or a heatwave, solar activity is not something you feel directly. But that doesn’t mean it’s harmless. The Sun’s high-energy particles can cause all kinds of problems.

Solar particles can disrupt satellites, GPS navigation, and radio signals. Power grids can take a hit too. A solar storm in 1989 knocked out electricity across Quebec, leaving millions without power.

The Carrington event of 1859 was the strongest solar storm we’ve ever seen. Telegraph systems went haywire. Some even sparked or shocked their operators. Auroras stretched so far south, they lit up the skies over the Caribbean.

“If a solar storm the size of the Carrington event occurred today, it could cause unimaginable damage to our modern, technology-dependent society,” said Professor Devika Kamath.

“Our interconnected digital world today is far more vulnerable than the simple telegraph networks of 1859. A similar event could disrupt everything from GPS navigation and mobile phone networks to banking systems and air traffic control, potentially causing trillions of dollars in damage.”

Lessons from the Sun

Dr. Chahal and his team weren’t just interested in the Sun’s current cycle. They looked at 138 other sun-like stars – ones that are younger and spin faster. Using over a decade of telescope data, they tracked how those stars’ magnetic activity behaved over time.

“Looking at younger, faster-rotating stars, and how their magnetic activity changes as they slow down with age, lets us see what our Sun may have been like in its youth and how its magnetic behavior has evolved over billions of years,” said Dr. Chahal.

For a while, scientists wondered if the Sun was a bit strange. Its cycles seemed unusually stable, but the research showed it’s not alone.

“We found several young sun-like stars with magnetic cycles similar to our Sun, but shorter,” noted Dr. Chahal. “As these stars age and slow down, they may evolve to have cycles like our Sun’s current 11-year cycle.”

A warning system for space weather

We depend on satellites more than we realize. From planes to GPS to global communications, much of modern life runs through space – and solar storms can shut it all down.

Research like this extends beyond the realm of astronomy. It connects stellar science to the stability of everyday life.

“Understanding the patterns of stellar activity cycles helps us better predict when dangerous space weather events might occur, not just around our own Sun but potentially around other stars with planetary systems,” said Professor Richard de Grijs.

“Our increasing dependence on satellite technology, GPS navigation, and interconnected digital systems means we need research like this to help us prepare for the space weather that’s an inevitable part of living with an active star.”

The full study was published in the journal Monthly Notices of the Royal Astronomical Society.

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