Why the Northern Lights will be harder to see over the next decade


By: By Kevin Byrne, AccuWeather staff writer

The northern lights are one of nature's most spectacular displays, but a change in solar activity may put viewing chances in jeopardy.

For those who wish to journey to a location where they can catch this phenomenon in person, the current solar cycle will make the lights appear less frequently.

The northern lights, also called the aurora borealis, often form when charged particles from the sun interact with Earth's atmosphere. The stream of charged particles that moves away from the sun is known as the solar wind.

A solar cycle can take 11 years. During this time, the circulation and flow inside the sun changes.

The least amount of solar activity, or when the fewest number of sunspots occur, takes place during solar minimum, which is where the cycle is currently headed. Sunspots are most numerous during solar maximum, and this part of the cycle is when auroras occur most frequently, according to NASA.

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"We are on track to reach solar minimum sometime between 2019 and 2022," Rodney Viereck, the head of research at the National Oceanic and Atmospheric Administration's Space Weather Prediction Center, said in an email to AccuWeather. "Then solar activity will slowly rise again."

Solar activity can take place in different forms, including solar flares, coronal mass ejections (CME), high-speed solar winds and solar energetic particles, NASA states. Geomagnetic storms tend to produce the brightest auroras, and they occur when a powerful CME or high-speed solar winds repeatedly impact Earth's magnetosphere.

However, despite the upcoming solar minimum, the lights can still be seen. Geomagnetic storms can develop during the minimum period but are more moderate in strength. During this time, the aurora is typically less bright, less active and becomes more localized.

"The aurora never really goes away, it just becomes less active and it moves farther poleward," Viereck said.

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Geomagnetic storms are rated on a scale from 1 (minor) to 5 (extreme). The more powerful a storm, the more widespread the aurora becomes as it extends towards the equator. The last storm of extended G5 strength occurred during October and November of 2003.

This last solar maximum was one of the smallest in the last 70 years, which resulted in fewer large geomagnetic storms. There were storms of G4 strengthas recently as March and June of 2015.

"We could still have a reasonably-sized storm during the last phase of the current solar cycle, but this is getting less and less likely," Viereck said.

During large events, auroras can be observed as far south as the United States, Europe and Asia. In 1859, a super solar flare developed and the northern lights were seen over tropical latitudes, including around Cuba and the Bahamas.

Until the cycle trends back toward solar maximum, those looking to view the northern lights in person aren't totally out of luck, it will just require a journey farther north or south.

"It will be a few years, maybe 2024 or 2025, before we will see the increase in geomagnetic activity of the next solar cycle," Viereck said. "Predicting solar activity is difficult, and we really don't yet know enough to provide more precise numbers on the timing an magnitude of the next cycle."

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