Backyard Universe: Miss the northern lights in Fayetteville? You may have another shot soon

It’s been a rather cloudy spring this year, but the sun sure has made some headlines lately.

Back on April 8, the moon slid in front of the sun in the last total solar eclipse the lower 48 will see for 20 years.  Then, just a month later, a series of large-scale events on the sun triggered a display of the aurora borealis or “northern lights” over all of the United States, including the South, where the phenomenon is rarely seen.

While both events are predictable, whether we see the northern lights over Dixie is more uncertain than the dead accurate solar eclipse predictions that can be calculated centuries ahead of time. Seeing the aurora down south is rare ... and special.

How to 'catch an aurora'

Most folks I’ve talked with locally who witnessed the northern lights display on May 10 saw it because they were watching for it. News reports about the major solar event that triggered the display were plentiful starting on May 8 when the solar event happened. That’s the best way to see a rare display of the aurora from our southerly location, not by chance but by deliberately watching. You have to be prepared to watch for it and have a clear sky, the darker the better. An unusually large sunspot was associated with the event.

I regularly monitor a couple of websites that provide current solar data and these sites can be invaluable for aurora watchers. Generally, charged particles spewed out from a solar flare or larger scale events called coronal mass ejections take about 48 hours to travel the 93 million miles from the sun to Earth. Some arrive earlier, some later but about two days is the travel time I’ve noticed during the half dozen times I’ve seen the northern lights locally over the past 40 years.

These particles interact with Earth’s magnetic field and gases in our upper atmosphere to create the colorful curtain-like aurora displays. The particles are drawn toward Earth’s poles which is why auroras are most common at high latitudes close to the north and south poles. It takes a major solar event to trigger a display at our southerly latitudes.

The site spaceweather.com offers daily solar updates and a new photo of the entire sun’s surface each day along with prospects for seeing an aurora at various latitudes.

Once an aurora is deemed possible, I start looking at the site Planetary K-index | NOAA / NWS Space Weather Prediction Center

This website gives the current planetary K-index, which is a real-time measure of how strong a geomagnetic storm can be as it wallops Earth. A typical look at the site when no storm conditions are happening will show a bunch of short, green vertical bars. When a sun-induced geomagnetic storm intensifies, however, these vertical columns can sometimes show red, indicating the possibility of an aurora becoming visible at southerly latitudes. It was this site that showed dark red bars late on the afternoon of May 10, indicating a G5 storm. It was almost a certainty then that I and others would likely see an aurora that evening given a clear sky, which we had over most of our area. I noticed the glowing aurora over in the northeastern sky during evening twilight that evening, before the sky was fully dark.

Although the May 10 aurora was a rare sight from our latitudes, we may see another soon. The 11-year solar cycle is predicted to reach its peak activity later this year or into 2025 and that peak is predicted to be at a higher level than earlier predictions made just months ago. All it will take will be for another large sunspot group to form creating a large energetic solar event that will once again send charged solar particles our way.

When it happens, the colorful dramatic evening sky of May 10 could play out again, assuming the solar storm conditions happen during nighttime over our area and our skies are clear.

If you have a question about astronomy send it to Backyard Universe, P.O. Box 297 Stedman, NC 28391 or email [email protected].

This article originally appeared on The Fayetteville Observer: When will northern lights be visible in Fayetteville, NC again?