Space weather could affect viewing
When we think of weather, we’re typically thinking of more terrestrial phenomena — snow, tornadoes and hurricanes. There’s also space weather, and it could impact images of the sun during the April 8 total solar eclipse.
What is space weather?
So what is space weather? NOAA defines it as “variations in the space environment between the sun and Earth,” which impacts technology in space and on the planet’s surface. This occurs in the form of radiation, wind and magnetic waves. Some varieties of space weather you may have heard of before are solar flares and solar wind.
While the dense gasses that form earth’s atmosphere aren’t found in outer space, there are very tiny amounts of gas, said Michael Richmond, professor of physics and astronomy at Rochester Institute of Technology. Some of those scattered molecules of gas are created by the sun, part of its extended outer atmosphere far beyond the center of the star. Atoms and particles in that outer layer of gas can escape from the sun and into the solar system or beyond.
“It’s the motions and collections and ‘clouds’ of this very, very tenuous material that people refer to as space weather,” Richmond said.
There are two main varieties of space weather, those happening near the visible surface of the sun, and those occurring near the upper layers of earth’s atmosphere, Richmond said. Those impacts closer to home occur when the number and energy density of the particles change.
Space weather events can have a wide-reaching impact on the planet, affecting a larger geographic area than normal weather systems. While the sun may be 93 million miles away, space weather can disrupt technology like satellites or air traffic control systems.
“If you’re a satellite with sensitive electronic equipment like computers inside you, and maybe some cameras, the changes in the very tenuous layer of particles that go flying past you might have some effect on your electronics,” Richmond said.
The activity that originates closer to the sun that qualifies as space weather includes phenomena like solar flares and coronal mass ejections.
What are coronal mass ejections?
Coronal mass ejections are large eruptions of plasma and magnetic field from the sun’s outer atmosphere, known as the corona, according to NOAA’s Space Weather Prediction Center.
A coronal mass ejection shot a burst of plasma toward the earth at 2 million miles per hour on April 21, 2023, causing a severe geomagnetic storm, according to NOAA. The ejection was rated at a 4 out of 5 on NOAA’s space weather G-Scale for tracking geomagnetic storms, capable of producing voltage control problems in power systems and surface charging and tracking problems on spacecraft.
The April 2023 coronal mass ejection also created a particularly spectacular aurora, allowing for viewing as far south as Arizona and Arkansas, according to NASA. The light of an aurora is caused by interactions between the expulsions from the sun and earth’s upper atmosphere. Coronal mass ejections Dec. 14-15 were the likely cause of impressive auroras over Canada.
What effect will solar activity have on the 2024 eclipse?
The major effect that solar activity, including the types that fall under the definition of space weather, will have on the eclipse is the appearance of the solar corona. The sun’s outer atmosphere gives the blinding sphere a translucent veil, but most of the time, our star is too bright for the corona to be visible. During a total solar eclipse, when the moon covers the sun completely, it’s possible to see the faintly glowing corona, Richmond said.
“It’s fascinating, it’s ghostly,” he said. “People really are amazed by it.”
The sun is particularly active near solar maximum — which is the case for the April 8 solar eclipse — with lots of solar flares and strong magnetic fields. This can make the sun’s corona brighter than normal or extend further from the sun, Richmond said.
Solar activity is on a roughly 11-year cycle, with sunspots and other activity more prevalent at maximum and reduced at the minimum of the cycle.
“And so it’s likely — no guarantees — but it’s likely that people who see this eclipse may see a bigger, brighter, more impressive corona than people who’ve seen other eclipses which weren’t at the solar max,” Richmond said.
The last total solar eclipse visible in the contiguous United States in 2017 was closer to solar minimum. The next eclipse visible in the contiguous U.S. is likely 20 years into the future, in 2044. The April eclipse will also cross over a more heavily area, with an estimated 31.6 million people in the path of totality, where you can see the moon completely block the sun.