The Aurora Borealis will soon be back


“Are we there yet?” asks the impatient youngster on a family vacation. And that’s the same question posed by the world’s aurora-watchers waiting for the current solar cycle to reach its peak.

Well, we’re almost there: Sunspot cycle number 24 is heating up. Two weeks ago, the strongest solar storm in years sent a shotgun blast of broken atom fragments in our general direction, and we got grazed enough to have had major displays not too far north of us. The Northern Lights also increase around the Equinoxes, when Earth and its magnetic field are sideways to the Sun. So the trigger may be primed just a few weeks from now, in March and April, for one of Nature’s greatest spectacles.

We’ve come a long way since the last high-level maximum, when sunspot cycle 22 peaked in 1989. On March 13 that year, a dazzling dusk-to-dawn aurora lit up the sky over our region from horizon to horizon. Huge electrical discharges coursed along the ground beneath the pulsating lights, tripping circuit breakers, plunging Quebec into darkness and causing garage doors throughout North America to open and close on their own.

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But back then we did not have today’s never-sleeping sentinels: SOHO, SDO, STEREO and other satellites watch violent clouds of plasma (broken atom fragments) break loose from the Sun at two million miles per hour to hurl the energy of one billion hydrogen bombs in our direction. The ACE spacecraft, hovering sunward of Earth, measures the actual subatomic debris as it sweeps by, to provide an hour’s warning of an imminent impact.

Initially flowing past us, some particles snap back and reverberate between Earth’s magnetic poles to create simultaneous auroral displays at both locations. Photos show that the complex glowing designs at each pole are exact mirror images of each other. Yet every aurora is just a segment of an enormous, spooky green ring hovering around each pole. Places like Fairbanks, Alaska that sit right below the glowing donut enjoy displays nearly every clear night.

The shimmering pale curtains with pink fringes typically occupy much of the Alaskan sky, but the displays around here often present a different face. Alaskans commonly gaze straight up from beneath the shimmering curtains, while we see them more obliquely from the side, which can actually ratchet up their majesty.

Still, it’s not truly rare for mid-Hudson observers to find themselves right under an expanded auroral oval during times of intense solar activity. We had wonderful displays here in 2000 and 2001. The unpredictability of the patterns is part of their lure. One may see rapid-fire split-second changes, or the pale green (or rarely, deep red) designs may unfold in slow motion, as glowing rays, blotches, arcs, lines, curtains or combinations – along with a profound accompanying silence that seems thoroughly out of place, given the sky’s visual turmoil.

Websites that may provide warning of solar storms and auroral action include www.gi.alaska.edu/auroraforecast and https://sec.noaa.gov/forecast.html, while www.spaceweather.com presents today’s conditions in an attractive format. For the more technically minded, even actual real-time activity detected by ACE is accessible at www.sec.noaa.gov/ace/mag_swepam_24h.html. This last site is meaty. Your key to reading the data is: You want to see the topmost white trace near the top, the density plot to be way over 10 particles per cc and the speed plot to be over 600 km/sec.

Once alerted, your own backyard is as far as you need travel around here, as long as the night is clear and the Moon not fat – unless you’re in the middle of Kingston, in which case a quick drive to the mountains is in order. But even in this high-tech age, many warnings prove to be false alarms. The people who catch the best auroras are those who simply check the northern sky from time to time on clear and especially moonless nights. For after seven years of low or nonexistent auroral activity around here, the next two years will almost definitely bring the glorious lights southward, to amaze those of us who cannot make an Alaskan pilgrimage.

 

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