SUNNY GAZE AHEAD
WHY THIS YEAR’S TOTAL SOLAR ECLIPSE MAY BE THE MOST DRAMATIC ONE IN YEARS
"IN THE PATH OF TOTALITY ONLY, WHEN THE MOON IS COMPLETELY COVERING THE SUN, YOU WILL BE ABLE TO SEE BASICALLY ALL THE STRUCTURE AROUND THE SUN. — KELLY KORRECK, NASA PROGRAM MANAGER FOR THE 2024 TOTAL SOLAR ECLIPSE
If you haven’t booked your trip to experience the total solar eclipse in April yet, here’s another reason: The sun might put on an extra fun show this time around. This year’s eclipse coincides with a period when the sun will be particularly active — at its most bustling in two decades.
In fact, the active sun will look very spiky, like a “very irritated little hedgehog,” solar physicist Scott Mcintosh said.
Every 11 years, the sun’s activity waxes and wanes as its north and south magnetic poles naturally switch places. The beginning of this solar cycle has the lowest activity, known as the solar minimum. Activity ramps up in the middle of the cycle, known as the solar maximum, and decreases again to the minimum.
The sun is approaching its maximum activity of its cycle this year, scientists say. That means it will be sending off more solar flares and eruptions from its surface — potentially making this year’s eclipse much more dynamic.
“In some ways, the sun’s more artistic or more complicated during a maximum,” said Kelly Korreck, NASA program manager for the 2024 total solar eclipse. “So being able to see that with your own eyes, it’s going to be very interesting.”
Here’s what to look for if you’re viewing the eclipse in the path of totality.
LOOK FOR THE STREAMERS
During a total solar eclipse, the moon blocks light from the sun’s disk, but part of the sun’s outer atmosphere — known as the corona — can be seen.
“In the path of totality only, when the moon is completely covering the sun, you will be able to see basically all the structure around the sun,” Korreck said.
The most obvious feature will probably be the presence of streamers, or bright streaks emanating from the sun. These are known as the solar wind, which is a stream of charged particles that is constantly blowing from the sun’s corona into space, Korreck said.
The solar wind, which can travel at more than one million m.p.h., helps ward off stray cosmic rays that may bombard Earth. A strong solar wind headed toward Earth can interfere with our satellite communications and impact our magnetosphere to trigger the northern lights.
When the sun’s activity is low, these streamers typically congregate around the poles because that’s where the magnetic field is radial, said Mark Miesch, a researcher with NOAA’S Space Weather Prediction Center. But during a solar maximum, he said, “all bets are off.”
“The streamers are not just at the north and south poles. They’re pretty much all latitudes,” Miesch said.
WATCH FOR GNARLY MAGNETIC LOOPS
The magnetic field is not uniform across the sun. Some areas, called active regions, have magnetic fields that are up to 1,000 times stronger than the sun’s average field. Active regions are usually the source for eruptions on the sun’s surface, which can cause disturbances on Earth and trigger the northern lights. The regions are more common during a solar maximum — and you may get the chance to see evidence of its magnetic complexity.
Look for loops that leave the sun’s side and connect back to the surface or incomplete loops of fingerlike structures protruding from the surface, Korreck said.
“These are great big loops that the magnets of the sun draw, then the plasma follows it,” she said. “That is part of normally active regions. It’s showing you the fact that the sun is magnetic.”
These loops, called prominences, will occur more often during solar maximum and can appear pinkish only during an eclipse due to glowing hydrogen and atmospheric scattering.
CROSS YOUR FINGERS FOR AN EXPLOSIVE LIGHT SHOW
One of the most exciting events on the sun is a coronal mass ejection (CME), or a large explosion of plasma and magnetic field from the sun’s corona. These can buffet the solar wind and incite geomagnetic storms on Earth, generating the northern lights or disrupting satellite communications.
Near solar maximum, scientists can observe an average of two to three CMES per day, according to NASA, but it takes a bit of serendipity for it to be in Earth’s view or path.
“My dream would be a solar maximum where we get one of the coronal mass ejections actively happening” during the eclipse, Korreck said. “It is possible for that to happen, but we have to keep our fingers crossed that sun’s going to put on a good show.”
During an eclipse, people would only see a phase of the eruption from where they’re standing over the course of a few minutes — perhaps something moving away or detached from the sun. A coronal mass ejection from beginning to end occurs over the span of an hour or more, but the entirety could be seen by stitching multiple images together taken by people across the path of totality.
Scientists will have a better idea of whether a coronal mass ejection will occur around a week before the eclipse, Korreck said. Researchers can monitor the location of active regions on the sun, where coronal mass ejections spawn from, and can make predictions on how active the sun will be during the eclipse.
There is potentially an even more exciting scenario: a northern lights display during the eclipse.
If a coronal mass ejection occurs a few days earlier and is directed toward Earth, it could incite a strong geomagnetic storm during the eclipse. Sky watchers in more northern latitudes could see a resulting northern lights, also known as an aurora borealis, during totality as the moon will darken the skies.
“It’s not impossible,” Korreck said. “It’s just maybe improbable that all the things align”
But it’s solar maximum, so crazy things could happen.