The Sun spins with heat as fusion reactions at its center produce large amounts of energy. Day after day, this energy is responsible for making the Earth habitable. But sometimes the sun’s radiation can burst, sending high-energy particles flying at top speed into space. If our planet is in the path of the radiation, it can wreak havoc on our lives.
These bursts of solar radiation make up what is called “space weather.” And it can be just as destructive as earth weather, though perhaps not as often as the headlines warn.
“Our star is really a huge fusion furnace. At its center, the temperature is between 15 and 17 million degrees Celsius, and approximately 600 million tons of hydrogen fuse into 596 million tons of helium,” says Madhulika Guhathakurtaprogram scientist for NASA’s Heliophysics Division and lead program scientist for “To live with a star” initiative that explores the ways in which the Sun-Earth system affects human life and society. Every second, these four million missing tones are transformed into energy – what we see as sunlight. But “even a slight change in this very uncertainly controlled activity can have drastic consequences on Earth,” she explains.
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Although such consequences are rare, satellites and technologies that rely on electricity and wireless networks are particularly vulnerable. In 1989 there was a geomagnetic storm a powerful solar flare caused a major power outage in Canada, which left six million people without power for nine hours. In 2000, a solar flare shorted some satellites and led to radio blackout. In 2003 a series of solar flares caused power outages and disrupted air travel and satellite systems. And in February 2022, a geomagnetic storm destroyed at least 40 Starlink satellites just as they were being deployed, costing SpaceX more than $50 million.
What exactly is space time?
Broadly speaking, the term “solar storm” describes when an intense burst of energy from the sun is shot into space and interacts with Earth. Charged particles are constantly drifting away from the sun into space in the so-called solar wind. But more significant flares can occur as solar flares, often from temporarily dark spots called sunspots and intense explosions called coronal mass ejections. Any kind of variation in this activity can cause auroras.
Solar flares are essentially flashes of lightning. They occur when strong solar magnetic fields protruding from the sun’s surface snap, releasing massive amounts of electromagnetic radiation at extremely high speeds. When this radiation hits Earth, it injects energy into our planet’s ionosphere, the uppermost part of our atmosphere, Guhatakurta explains. Extreme ultraviolet radiation from the sun can polarize particles in Earth’s ionosphere, she says, which can have cascading effects on any other charged particles nearby—meaning anything that uses electricity is at risk.
And solar flares travel at the speed of light, he says Jesse Woodruff, who directs the space weather research program in NASA’s Heliophysics Division. This makes them difficult to predict and prepare for. “There’s no way to get a signal to Earth faster than solar flares, which are already traveling at the speed of light,” he notes. “So you have to predict that the eruption itself is going to happen. And it’s a challenging scientific problem that we haven’t cracked yet.
While solar flares are intense bursts of radiation, a coronal mass ejection is an explosion of energetic particles. As such, they travel a little slower. They occur when large parts of the sun’s outer atmosphere (the corona) explode, sending superheated gas into space. These “large blobs of solar material are ejected at very high speeds, hundreds and hundreds of kilometers per second, but it’s much slower than the speed of light,” adds Woodroffe. They can take half a day to three days to reach Earth, he says.
How to forecast solar storms
Weather forecasting in space is not quite like weather forecasting on earth. The big difference: on Earth, meteorologists have millions of measurements they can take and integrate into their forecast models. In space, Woodroffe says, there are only a few places where scientists can place instruments to observe solar activity.
“We don’t have a good picture of what’s going on between the sun and the Earth,” he explains. “There are very few places where you can put a reliable asset to sit there and watch satellites in orbit move.” Lagrange points are rare spots between the Earth and the sun where the gravity of both objects equally pulls a satellite to hold it in place. This is where NASA has placed its “most important space weather monitors,” says Woodroffe, including the Solar Dynamics Observatory and a joint venture with the European Space Agency (ESA). ESA is developing another mission, called Vigil, to place a spacecraft at a Lagrange point near the sun by the end of this decade.
With their cameras and sensors, scientists watch the sun for a change in brightness coming off its surface, Woodroffe explains. An increase in brightness may appear in just a few frames and last only a few seconds.
NASA shares data from its solar observatories with the National Oceanic and Atmospheric Administration, which provides probabilistic forecast for geomagnetic storm warnings and watches based on probability and geomagnetic intensity. Depending on how fast the solar storm is moving, they can send warnings several days before space weather hits Earth or just a few hours.
The ultimate goal, Woodroffe says, is to improve space weather forecasting to equal hurricane forecasting. His Earth-focused colleagues can predict where a hurricane might go by using different models, producing a set of results with a high degree of certainty, he says. “We are developing such capabilities for space weather.”
In the area of the sun
So, back to those apocalyptic solar flare headlines. Is the sun really growing fiercer and threatening to collapse modern society every week?
Space weather activity hasn’t changed recently, says Guhathakurta, but humanity has. Over the past century, people have become increasingly reliant on electronics, and anything with “an on-off switch is vulnerable to solar storms,” she says.
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When these energetic particles come from the sun to Earth, the perturbation they cause in our planet’s magnetic field “creates electromagnetic fluctuations and voltage fluctuations that can penetrate underground and create fluctuations in our electrical grid,” says Guhatakurta. And with increasing reliance on devices that rely on orbiting satellite systems like GPS, our electronics are even more exposed to bursts of solar radiation.
To reduce the risk of power outages and tools burning out from a solar storm, tech companies can build back-up power systems and other redundancies into their devices and strategically turn them off when NOAA’s Space Weather Prediction System flags a high risk.
“Human civilization extends from our terrestrial domain into the heliosphere, or the domain of the sun,” says Guhatakurta. “We no longer merely observe an environment that is beyond our reach, but actually live in it, trade in it, and travel in it. Therefore, we must truly achieve the level of understanding necessary to develop and inhabit this new world.