Washington CNN  —  Buckle up: An unusual amount of solar activity this week could disrupt some of the most important technologies society relies on. On Thursday, the US government issued its first severe geomagnetic storm watch in nearly 20 years, advising the public of “at least five earth-directed coronal mass ejections” as well as sunspots covering an area 16 times wider than the earth itself. Radiation from this activity will begin to hit Earth’s magnetic field on Friday and last through the weekend, said the National Oceanic and Atmospheric Administration. NOAA’s severe space weather watch suggests the storm could trigger numerous effects for life on Earth, possibly affecting the power grid as well as satellite and high frequency radio communications. Here’s what that means for technology users. Communications impacts The solar activity NOAA’s talking about involves the release of energy from the sun that travels through space and eventually reaches Earth. When that radiation hits the magnetic sphere surrounding the planet, it causes fluctuations in the ionosphere, a layer of the upper atmosphere. Those changes can directly affect satellites and other spacecraft in orbit, altering their orientation or potentially knocking out their electronics. Moreover, the changes to the ionosphere can block or degrade radio transmissions trying to pass through the atmosphere to reach satellites. And they can also prevent radio transmissions from successfully bouncing off the ionosphere — which some radio operators normally do to increase the range of their signals. Since GPS satellites depend on signals penetrating the ionosphere, the geomagnetic disturbance scientists are expecting could affect that critical technology used by planes, ocean-going vessels, and in the agriculture and oil and gas industries. And it could affect shortwave radio transmissions used by ships and aircraft, emergency management agencies, the military and even ham radio operators, all of whom rely on the high frequency radio airwaves that NOAA says could be scattered by the storm. “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,” NOAA’s Space Weather Prediction Center said in a release. “SWPC has notified the operators of these systems so they can take protective action.” What about your cellphone? Consumer wireless networks rely on different radio frequencies than the high frequency band, so it appears unlikely that the storm will directly affect cellular service. The GPS features on your phone also typically use a mix of pure GPS and cellular tower-based location tracking, so even if GPS signals are disrupted, phone users may still be able to maintain a rough location fix. So long as the underlying electrical infrastructure that supports wireless networks remains unaffected, even an extreme space weather event should result in “minimal direct impact to public safety line of-sight radio and commercial cellular services … and no first-order impact to consumer electronic devices,” according to researchers summarizing the findings of a 2010 study of extreme space weather conducted by NOAA and the Federal Emergency Management Agency. The Cybersecurity and Infrastructure Security Agency outlined a similar report in a 2021 presentation on space weather, finding that line-of-sight radio transmissions are generally not affected by space weather except in specific situations. The presentation did note some risks for copper cables and telephone lines based on land. In a slightly different scenario in February, NOAA noted two major solar flares. But despite “widely reported cellular network outages” around the same time, the agency said, it was “highly unlikely” that the flares played a role in those blackouts. The power grid is potentially at risk Severe space weather can jeopardize power grids, according to NOAA, whose alert this week said to expect “possible widespread voltage control problems” and that “some protective systems may mistakenly trip out key assets from the power grid.” In 1989, a space weather event led to a massive blackout in Quebec, Canada for more than nine hours after geomagnetic fluctuations damaged transformers and other important equipment. In October, an extreme geomagnetic storm stronger than the one predicted for this weekend led to power outages in Sweden and damaged power transformers in South Africa, the SWPC said. The largest known geomagnetic storm in history, known as the Carrington Event of 1859, caused telegraph stations to spark and catch fire. A blackout of the electrical grid could have cascading effects for communications and other technologies, including cellphones. Cellular towers might lose power, as could the data centers that host websites and their information. So the US government’s advice to the public on how to prepare for a space weather event largely resembles the same steps you’d take in response to an extended power outage. to this report.