Thursday update: The predicted solar storm on Earth predicted for Thursday evening has been downgraded from “strong” to “minor” by NOAA’s Space Weather Prediction Center. As such, auroras are no longer expected in the northern Lower 48 states. See: Solar storm and potential for auroras in northern U.S. fizzle

Original article from Tuesday

After a lengthy slumber, the sun is waking up, crackling with activity and hurling blistering pulses of energy into space. Solar physicists are expecting an uptick in stormy “space weather,” with implications that affect us here on Earth.

As soon as Thursday, the National Oceanic and Atmospheric Administration is predicting that a solar outburst could generate northern lights or aurora as far south as Oregon to Pennsylvania.

This flare-up coincides with the onset of “Solar Cycle 25,” an 11-year window within which storminess on the surface of the sun peaks and “solar storms” become routine.

The sun is nearly 93 million miles away, but disturbances on its surface can have serious effects far and wide across the solar system. Solar scientists and forecasters of space weather track “sunspots,” or cool, discolored regions that make appearances on the solar disk. The number of sunspots present at any given time fluctuates over the course of 11 years, each span representing one cycle.

Sunspots are often the source of solar flares, which can cause high-frequency radio blackouts and interrupt communications on Earth. At the same time, sunspots may also release coronal mass ejections, which are sneeze-like eruptions of magnetic energy, that can bring about occasionally epic displays of the northern lights.

Twice in the past 10 days, impressive solar flares have heralded the building Solar Cycle 25, a stark contrast from earlier this year, when a “solar minimum” between cycles meant that 200 days didn’t feature a single sunspot. During the heart of a solar cycle, more than 100 sunspots can crop up in a single month.

On Nov. 29, a M4.4-class solar flare erupted behind the east limb of the sun. Solar flares are ranked on a five-tier scale: A-class flares are the smallest, followed by B, C, M and eventually X-class flares. Some even thought that flare, which was the strongest in three years, may have been an X-class, but measurement was challenging since it was facing away from Earth.

Then on Monday, a C7.4-magnitude flare blossomed, directly facing Earth. A coronal mass ejection also hurled toward the planet, likely to arrive late Wednesday or Thursday.

NOAA’s Space Weather Prediction Center in Boulder, Colo., is highlighting the potential of the northern lights reaching as far south as the northern United States. It issued a geomagnetic storm “watch,” noting a Level 3 (out of 5) or “strong” storm could occur on Earth on Thursday.

In its watch bulletin, the center cautioned that the storm could also increase drag on low-Earth-orbit satellites and intermittently affect their orientation and navigation.

“This is NOT a major space weather event,” wrote. “But after 3 years of uber-quiet Solar Minimum, it is noteworthy.”

Solar Cycle 25 is expected to peak in July 2025. That’s when sunspots will be the most numerous, as magnetic energy, or flux, bubbles to the sun’s surface from deeper down in the plasma body. Any sunspot can produce flares and coronal mass ejections that can be disruptive to Earth; during solar maximum, there are many more opportunities for that to happen.

Earth-directed solar storms have damaged power grids and disrupted satellite communications. Concerns remain that a particularly intense geomagnetic storm could cause serious damage to these systems.

Advanced forecasts from the Space Weather Prediction Center are designed to offer enough lead time to protect critical infrastructure from damage before it could occur, but concerns have been raised about their adequacy.

Meanwhile, sky-watchers at high latitudes can expect more opportunities to see the northern lights in the years ahead. And as we roll the dice enough times, there’s even a chance that a strong-enough solar storm could spill aurora into the middle latitudes.

The spike in solar unrest could also make for an even more spectacular show Monday, when a total solar eclipse will plunge a swath of Chile and Argentina into a midday darkness.

When the moon blocks the sun during totality, the solar corona, or the sun’s atmosphere, will be visible to the naked eye. The corona traces lines of magnetic field wrapping around the sun and connecting between its poles and the equator. With more sunspots peppering the surface and more flares, the corona is bound to be more interesting than during last year’s eclipse, with glorious prominences radiating out from behind the jet-black, void-like moon.

Predictive Science, a San Diego-based solar modeling company, used supercomputers and data captured by satellites to simulate the rapidly evolving magnetic field of the sun. On Monday, it released a final prediction for what the solar corona may look like during next week’s solar eclipse. During the eclipses of 2017 and 2019, its predications verified with impressive accuracy.

The company notes that its models revealed a 50 percent uptick in magnetic flux, or energy, pouring out of the surface of the sun in just the past 2½ weeks, attesting to how quickly Solar Cycle 25 is arriving. As a result, Predictive Science anticipates eclipse-watchers can expect a dynamic corona.

Jason Samenow contributed to this report.