For the third time this week, people across portions of the United States may get the chance to see the northern lights. A solar storm is expected to hit Earth on Thursday, potentially bringing the dancing lights as far south as Alabama and California on Thursday night.

But the influx of solar energy and particles, poised to arrive just after Hurricane Milton hits Florida late Wednesday or early Thursday, could affect power systems and satellite operations, including low Earth-orbiting commercial satellites.

“We just don’t know all the implications, so we’re doing a little more advertising than usual,” Shawn Dahl, the service coordinator for NOAA’s Space Weather Prediction Center, said in a news conference Wednesday. He said NOAA already contacted North American power grid operators and guarantees “they’re already taking precautions and measures to prepare for the storm should it materialize as we anticipate.”

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NOAA has also been briefing the Federal Emergency Management Agency, who is mobilizing relief efforts for Milton as well as Hurricane Helene that hit Florida two weeks ago and caused major damage in western North Carolina.

Earth is forecast to experience a “severe” geomagnetic storm, ranked 4 out of 5 on the severity scale, according to a watch by the National Oceanic and Atmospheric Administration. During past storms of this magnitude, power grid operators have largely managed to keep systems online, but satellites such as Starlink that provide internet service have reported issues.

Storms this strong can also produce aurora into the southern United States, although locations in the northern regions have a much better chance at seeing the lights. In southern regions, the opportunity to see aurora is best away from cities and light pollution. Auroras, particularly in southern locations, are more easily seen using a long camera exposure than the naked eye.

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Skies should be mostly clear across the Mid-Atlantic and Midwest on Thursday night, but may be cloudier in the Northeast and Pacific Northwest.

As an added bonus, sky watchers may be able to see a bright, rare comet, Comet Tsuchinshan–ATLAS, in the wee hours of the night in the United States, although binoculars are beneficial to initially spot it. It will be the brightest on Wednesday night but will make its closest approach to Earth on Saturday.

Auroras are generated when a surge of particles, energy and bits of magnetic field from the sun temporarily disturb Earth’s protective magnetic bubble, creating a geomagnetic storm. Some solar particles trapped in our planet’s magnetic field lines are accelerated into our upper atmosphere, where they can hit nitrogen and oxygen atoms. As they excite the atoms, they release photons of light in different colors.

The surge of solar particles for this anticipated geomagnetic storm came from a coronal mass ejection, a large explosion of plasma from the sun’s surface, that left the sun Tuesday evening. Satellite data shows the particles are headed directly toward Earth at speeds of 750 to 800 miles per second. The surge could arrive as early as Thursday morning to midday, and could extend into Friday.

Forecasters won’t know the exact strength and timing of this coronal mass ejection until satellites observe it about 1 million miles away — giving about an hour or less lead time for us on Earth.

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The event is the second geomagnetic this week, which brought aurora sightings to the northern half of the United States on Sunday and Monday. The “strong” storm (ranked 3 out of 5 in severity) was weaker than it was predicted to hit, but it still brought aurora down to Maryland and other southern states. NOAA said there were “no significant impacts" to communication systems from the storm.

When and where will be the best places to see the northern lights?

Particles from the sun take a few days to reach Earth. The coronal mass ejection left the sun Tuesday, but it is moving relatively fast and is expected to hit Earth as early as Thursday morning. However, sometimes events can arrive much later. For instance, a solar storm that was supposed to hit last Friday was delayed by 48 hours.

As of Wednesday morning, NOAA issued a severe geomagnetic storm watch for Thursday and Friday. During severe storms, the agency said aurora can be seen as far south as Alabama and Northern California. But others have reported aurora sightings in areas farther south with their cameras and cellphones, which are more sensitive to light than our eyes.

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Clear skies should make for a good show for the Mid-Atlantic and Midwest from the early morning hours Thursday through largely Friday morning. The Northeast and Pacific Northwest may have cloudier skies.

How will this affect communications systems or the power grid during Hurricane Milton?

As a severe solar storm hits Earth, the surge of particles can overload energy systems and interrupt satellite communications. The timing of this storm could hit hours to days after Hurricane Milton hits, making landfall near or just south of Tampa Bay and then moving east across Florida.

On its website, NOAA stated a severe storm of this level (ranked 4 out of 5) could cause widespread voltage control problems. Spacecraft may also experience surface charging and tracking problems, satellite navigation could be degraded for hours and low-frequency radio navigation could be disrupted.

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NOAA rarely issues watches for severe geomagnetic storms, putting out just two in the past two decades. The last watch was issued for a storm in May 2024, which ended up increasing in severity (ranked 5 out of 5) and brought aurora throughout the United States. Planes rerouted because of radio signal interference, and power systems experienced voltage irregularities. Some GPS systems stopped working, including precision GPS systems that were off by feet. Starlink and Amazon satellites were also put in safe mode and moved out of orbit.

Any emergency response systems operating in certain wavelengths or bands should be alert of the incoming solar storm, Dahl said in the press conference Wednesday. Some systems may be affected, and some won’t. NOAA will be briefing FEMA again on Thursday.

Solar activity in the past has affected emergency and disaster response after hurricanes. During the September 2017 hurricane season, a series of solar eruptions disrupted radio communications for ground and air traffic support helping with recovery efforts in the Caribbean region after Hurricanes Harvey, Irma, Jose and Maria hit the region. The solar events temporarily complicated efforts to respond to these hurricanes, scientists said.

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One factor potentially protecting Florida is its southern latitude, said Mike Bettwy, operations chief at NOAA’s Space Weather Prediction Center. It would require a very strong storm to reach the state.

“In order for [Florida] be affected, the [solar] storm would need to go pretty far south,” said Bettwy. That’s not a given for this storm and “adds a little a bit more to the comfort level."

What caused this storm?

On Tuesday evening, the sun emitted a powerful solar flare for several hours. Solar flares are sudden, intense bursts of light from the sun, releasing energy comparable to billions of hydrogen bombs. This solar flare was ranked a X1.8, where X is the highest classification and higher numbers are stronger flares.

Solar flares do not create the surge of solar particles that lead to the aurora on Earth, But they are often associated with the explosions that do — called coronal mass ejections. As the solar flare was lifting off the sun’s surface, a coronal mass ejection also exploded from the center of the sun Tuesday and pointed directly toward Earth.

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The coronal mass ejection is barreling toward Earth at 2.5 million miles an hour, which NOAA said is the fastest Earth-direction ejection since 2017 (the start of the current solar cycle). When the ejection reaches satellites about 1 million miles away, scientists will analyze it more deeply to better gauge the intensity of the geomagnetic storm.

NOAA forecasts have a high level of confidence in when the coronal mass ejection will reach Earth, but Dahl said “intensity is always the question at hand.”

Once it hits, sky watchers could see an aurora shortly after if skies are clear.