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Solar eclipse.
© Gabi Siebenhühner/Imago
The US will see a rare total solar eclipse in April.
It could be particularly interesting in 2024 – the peak of solar activity.
If you haven't already booked a trip to see the total solar eclipse in the United States in April, now you have another reason: The sun could put on an especially fun show this time.
This year's solar eclipse comes at a time when the sun will be particularly active - more active than it has been in two decades.
In fact, the active Sun will look very spiky, like a "very irritable little hedgehog," said solar physicist Scott McIntosh.
Every 11 years, the sun's activity waxes and wanes as the sun's north and south magnetic poles swap places.
At the beginning of this solar cycle, activity is at its lowest, which is called the solar minimum.
In the middle of the cycle, the solar maximum, activity increases and then falls back to the minimum.
According to scientists, the Sun is approaching the maximum activity in its cycle this year.
That means it will emit more solar flares and solar storms from its surface - which could make this year's total solar eclipse much more dynamic.
“In some ways the sun is more elaborate or complicated during a maximum,” said Kelly Korreck, NASA program manager for the 2024 total solar eclipse. “If you can see that with your own eyes, it will be very interesting.
If you want to observe the solar eclipse in the path of totality, here are some things to keep in mind.
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Total solar eclipse in the USA: Watch out 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 - called the corona - can be seen.
Under normal conditions we cannot see the corona because the bright light from the sun's disk washes it out.
In addition, it is very dangerous to look at the sun with naked eyes.
“Only in the totality phase, when the moon completely covers the sun, can you see practically all the structures around the sun,” says Korreck.
The most noticeable feature will likely be the bright streaks emanating from the sun.
“This is the solar wind, a stream of charged particles that is constantly blown into space by the sun’s corona,” says Korreck.
The solar wind, which can travel at more than 1 million kilometers per hour, helps ward off stray cosmic rays that could bombard Earth.
A strong solar wind heading toward Earth can disrupt our satellite communications and affect our magnetosphere, triggering the northern lights.
When solar activity is low, these streamers typically gather around the poles because the magnetic field there is radial, said Mark Miesch, a researcher at the NOAA Space Weather Prediction Center.
But during a solar maximum, Miesch said, “all bets are off.”
“The streamers are not just at the north and south poles.
They can be found at pretty much all latitudes,” says Miesch.
Total solar eclipse in April: Watch out for gnarly magnetic loops
The magnetic field is not the same everywhere on the sun.
In some areas, called active regions, magnetic fields are up to 1,000 times stronger than the sun's average field.
Active regions are typically the source of flares on the sun's surface, which can cause disturbances on Earth and trigger the northern lights.
During a solar maximum, these regions are more common - and you may have the opportunity to find evidence of their magnetic complexity.
Look for loops that leave the sunny side and reconnect to the surface, or incomplete loops with finger-like structures protruding from the surface, Korreck said.
"These are large loops drawn by the sun's magnets, and the plasma follows them," she said.
“This is part of the normally active regions.
This shows us that the sun is magnetic.”
These loops, called prominences, are more common during solar maximum and can only appear pink during a solar eclipse due to glowing hydrogen and atmospheric scattering.
Solar eclipse in April 2024: Keep your fingers crossed for an explosive light show
One of the most exciting events on the Sun is a coronal mass ejection, which is a large explosion of plasma and magnetic field from the Sun's corona.
These can stir up the solar wind and trigger geomagnetic storms on Earth, produce the northern lights or disrupt satellite communications.
According to NASA, scientists can observe an average of two to three CMEs per day near the solar maximum, but it takes a bit of luck for them to be within sight of Earth or in its orbit.
“My dream would be a solar maximum where we actively experience one of the coronal mass ejections during the eclipse,” Korreck said.
“It’s possible that this will happen, but we have to keep our fingers crossed that the sun will put on a good show.”
During a solar eclipse, people would only see a phase of the outburst from their location lasting a few minutes - perhaps something moving away from or breaking away from the sun.
A coronal mass ejection from start to finish spans an hour or more, but the entirety could be seen by stitching together several images taken by people in the path of totality.
About a week before the eclipse, scientists will have a better idea of whether a coronal mass ejection will occur, Korreck said.
Researchers can monitor the location of active regions on the Sun where coronal mass ejections occur and can make predictions about how active the Sun will be during the eclipse.
There is a potentially even more exciting scenario: an aurora borealis during the solar eclipse.
If a coronal mass ejection occurs a few days earlier and is aimed at Earth, it could trigger a powerful geomagnetic storm during the eclipse.
Sky watchers in more northern latitudes may see a northern lights, also known as an aurora borealis, during totality as the moon will darken the sky.
“It’s not impossible,” Korreck said.
“It's just perhaps unlikely that all things will fit together.
But it's solar peak, so crazy things could happen.
About the author
Kasha Patel
writes the weekly Hidden Planet column, covering scientific topics surrounding Earth, from our inner core to space storms headed toward our planet.
She also reports on weather, climate and environmental issues.
We are currently testing machine translations. This article was automatically translated from English into German.
This article was first published in English on January 26, 2024 at the “Washingtonpost.com” - as part of a cooperation, it is now also available in translation to readers of the IPPEN.MEDIA portals.