More displays of Northern Lights are likely this weekend and in the coming weeks after scientists discovered more sunspots on the sun during July 2024 than at any time since December 2001.
Sunspots are magnetic disturbances on the sun’s surface that can be as big as Earth. They’re counted daily since 1611, indicating how magnetically active the sun is. The monthly average sunspot number for July 2024 reached 196.5, according to the Royal Observatory of Belgium’s Solar Influences Data Analysis Center.
This follows a week of “photographic displays” of Northern Lights in North America, which are now likely to be repeated this weekend. Sunspots are where solar flares on the sun originate, often followed by coronal mass ejections (CMEs).
Solar flares can cause radio blackouts but not aurora. However, CMEs hurl magnetic fields and charged particles into the solar system at up to 1,900 miles per second. If they’re traveling in Earth’s direction, they can cause geomagnetic storms, which is what causes the Northern Lights.
In the wake of an M8-class solar flare, an Earth-directed CME is expected to arrive this weekend, likely triggering a G2-class geomagnetic storm. This means that people as far south as New York and Idaho may see the aurora on their northern horizon.
May’s extreme G5 geomagnetic storm was rated as a G5—the highest possible—but that’s not what’s happening this weekend. The sun has a roughly 11-year solar cycle during which its magnetic activity waxes and wanes. It’s now on the cusp of “solar maximum”—its peak period of activity—determined by counting sunspots.
The Northern Lights are caused by the solar wind, a stream of charged particles from the sun. As they strike Earth’s magnetic field, they accelerate down its magnetic field lines at the north and south poles to create ovals of green and red.
Source: https://www.forbes.com/sites/jamiecartereurope/2024/08/03/northern-lights-alert-solar-activity-at-23-year-high-scientists-say/