Northern lights may be visible across parts of the US this weekend. Why are they so active right now?

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A series of solar flares and coronal mass ejections from the sun have the potential to create dazzling auroras that may be seen as far south as Alabama and Northern California but also disrupt communications on Earth tonight and over the weekend, according to the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center.

The center, which is a division of the National Weather Service, issued a severe geomagnetic storm watch for Friday evening. It’s the first such watch issued since January 2005.

As the sun nears the peak of activity in its 11-year cycle, known as solar maximum, later this year, researchers have observed increasingly intense solar flares erupting from the fiery orb.

Increased solar activity causes auroras that dance around Earth’s poles, known as the northern lights, or aurora borealis, and southern lights, or aurora australis. When the energized particles from coronal mass ejections reach Earth’s magnetic field, they interact with gases in the atmosphere to create different colored light in the sky.

The Space Weather Prediction Center tracked multiple strong flares emitting from a large cluster of sunspots on the solar surface since Wednesday. The cluster is 16 times the diameter of Earth.

Scientists observed at least five coronal mass ejections, or large clouds of ionized gas called plasma and magnetic fields that erupt from the sun’s outer atmosphere, releasing from the sun in the direction of Earth. These significant outburts are expected to arrive as early as midday Friday and continue through Sunday.

The peak of the geomagnetic storm activity for Earth will be between 2 a.m. and 5 a.m. ET on Saturday, according to the center’s forecast.

The center referred to this as “an unusual event.”

Geomagnetic storms driven by the sun in recent months have caused auroras to be visible in places where they are rarely seen, including as far south as New Mexico, Missouri, North Carolina and California in the United States, and the southeast of England and other parts of the United Kingdom.

Depending on the location, the auroras may not always be visible overhead, but keep an eye on the horizon, experts say, because they may create a colorful display there as well.

The aurora borealis can be seen on the north horizon in the night sky over Wolf Lake in the Cloquet State Forest in Minnesota in September 2019. – Alex Kormann/Star Tribune/Getty Images

The effects of geomagnetic storms

When directed at Earth, these ejections can cause geomagnetic storms, or major disturbances of Earth’s magnetic field.

“Geomagnetic storms can impact infrastructure in near-Earth orbit and on Earth’s surface, potentially disrupting communications, the electric power grid, navigation, radio and satellite operations,” according to the Space Weather Prediction Center. “(The center) has notified the operators of these systems so they can take protective action.”

Solar storms generated by the sun can also cause radio blackouts and even pose risks for crewed space missions.

The center warned that additional solar activity could cause geomagnetic storm conditions to be ongoing through the weekend.

So far, researchers have obseverd only three severe geomagnetic storms during the current solar cycle, which began in December 2019, according to the center.

Previously, a G5, or extreme geomagnetic storm, occurred on October 23, resulting in power outages in Sweden and damaged power transformers in South Africa, according to the center.

Tracking space weather

Every 11 years or so, the sun experiences periods of low and high solar activity, which is associated with the amount of sunspots on its surface. The sun’s strong and constantly shifting magnetic fields drive these dark regions, some of which can reach the size of Earth or larger.

Over the course of a solar cycle, the sun will transition from a calm to an intense and active period. During the peak of activity, called solar maximum, the sun’s magnetic poles flip. Then, the sun will grow quiet again during a solar minimum.

Solar maximum is expected to peak through mid- to late 2024, but the sun will remain active for a couple of years afterward.

Teams at the Space Weather Prediction Center use data from ground and space-based observatories, magnetic maps of the solar surface, and ultraviolet observations of the sun’s outer atmosphere to determine when the sun is most likely to send out solar flares, coronal mass ejections and other space weather that could affect Earth.

Solar flares can affect communications and GPS almost immediately because they disrupt Earth’s ionosphere, or part of the upper atmosphere.

Energetic particles released by the sun can also disrupt electronics on spacecraft and affect astronauts without proper protection within 20 minutes to several hours.

The material sent speeding away from the sun during coronal mass ejections can arrive at Earth between 30 and 72 hours afterward, causing geomagnetic storms that affect satellites and create electrical currents in the upper atmosphere that travel through the ground and can have an impact on electric power grids.

The storms also affect flight patterns of commercial airlines, which are instructed to stay away from Earth’s poles during geomagnetic storms due to loss of communication or navigation capabilities.

Extreme storms have occurred before, such as one that knocked out the power grid in Quebec in 1989 and the Carrington Event of 1859.The latter remains the most intense geomagnetic storm ever recorded, causing telegraph stations to spark and catch fire.

If such an event were to occur today, it could cause trillions of dollars’ worth of damage and bring down some power grids for a substantial amount of time.

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