A solar flare sent an outburst of plasma and charged particles hurtling towards Earth on Thursday.
As a result, the National Weather Service predicts a strong solar storm at Earth's poles Saturday.
The solar storm could bring the aurora borealis south, from Pennsylvania to Iowa to Oregon.
An eruption on the surface of the sun on Thursday sent an outburst of plasma and magnetically charged particles directly toward Earth.
That solar flare is leading waves of radiation and plasma to wash over the planet. On Saturday, that could bring the aurora borealis so far south that it'd be visible across the northern US, from Pennsylvania to Iowa to Oregon.
The aurora appears when Earth's magnetic field channels electrically charged solar particles toward the poles, where the particles interact with gases in Earth's atmosphere. That's what creates ribbons of bright colors.
When solar flares send floods of those particles towards the Earth, that causes a geomagnetic storm, which can produce particularly stunning auroras.
The space-weather branch of the National Weather Service classified Thursday's eruption as an X1 flare. X is the most powerful class of solar eruption, but the number 1 indicates that it's the lowest intensity within that category. As a result, the agency is predicting a strong geomagnetic storm on Saturday.
"The X1 flare occurred right the center of the solar disc as seen from Earth, so perfect geometry to affect Earth," Mike Hapgood, a space-weather consultant at the Rutherford Appleton Laboratory in the UK, told Insider.
Solar storms don't just bring pretty auroras, though. The inundation of solar particles can also interfere with power grids, GPS, and radio communications, and even affect satellites' orbits around Earth.
This particular upcoming storm "could cause some minor problems," Hapgood said, but "ones that should be easily fixed - not anything to cause concern."
Southern-reaching auroras could become more common
Scientists expect more solar flares, geomagnetic storms, and far-reaching auroras in the coming years. That's because the sun is at the beginning of an 11-year solar cycle, which means its eruptions and flares will grow more frequent and violent, ramping up to a peak in 2025.
Earlier this month, another solar flare created a smaller geomagnetic storm at Earth's poles. It produced bright auroras that astronaut Shane Kimbrough photographed from the space station.
"There's nothing unusual about this event from a scientific viewpoint, it's a modest space weather event," Hapgood said. "The current event is just the most striking Earth-directed event, so far, of the new solar cycle."
Strong solar storms are fairly common - the NWS estimates that each solar cycle produces about 200 of them - but scientists can't always predict them the way they did this time. A surprise solar storm, however, can leave power grids and key radio connections vulnerable.
NASA is working to better predict space weather
Electric currents from solar storms can travel down Earth's pipelines and power lines, overpowering technologies that humans rely on.
In 1989, an inundation of particles from the sun knocked out Quebec's power for about nine hours. Two other solar storms cut off emergency radio communications for a total of 11 hours shortly after Hurricane Irma in 2017. A solar storm may have even cut off SOS broadcasts from the Titanic as it sank on April 14, 1912, but that's not known for sure.
Bursts of solar activity can also endanger astronauts in Earth's orbit by interfering with their spacecraft or knocking out communications to mission control.
So studying the source of charged solar particles could help scientists figure out how to protect both astronauts and Earth's electric grid from these unpredictable electrical storms. Two spacecraft currently orbiting the sun are doing just that.
In February 2020, NASA and the European Space Agency launched the Solar Orbiter to capture data about eruptions on the sun's surface. NASA's Parker Solar Probe is also zooming around the sun. It's designed to measure solar eruptions as they happen, tracing the flow of material from the sun to the Earth in real-time.
The information these spacecraft are collecting could one day help scientists forecast more geomagnetic storms before they happen.