What Would Happen if a Solar Storm Hit Earth?

A solar storm involves disturbances on the sun, such as solar flares and coronal mass ejections (CMEs), which release streams of energetic particles and massive bubbles of gas threaded with magnetic field lines into space.

These events can impact Earth and other planets when the particles interact with planetary magnetic fields and atmospheres.

These storms often follow sunspot cycles and can propel particles toward Earth at high speeds. When these particles collide with Earth's magnetic field, they can cause geomagnetic storms that result in beautiful auroras, also known as the northern and southern lights.

However, they can also pose risks to satellites, power grids and communication networks. The intensity of solar storms can vary, with some being minor and causing little effect, while others can be powerful enough to disrupt Earth's magnetosphere and ionosphere, leading to significant technological disturbances.

The NOAA Space Weather Scales is a standardized system developed by the National Oceanic and Atmospheric Administration (NOAA) to rank and categorize the severity of space weather events, specifically geomagnetic storms.

Much like the scales used for tornadoes or hurricanes, NOAA's scale provides a clear framework for understanding the potential impact of these celestial disturbances on Earth and its technological infrastructure.

The scale ranges from 1 (minor) to 5 (extreme) and is based on the potential impact on power systems, satellite operations and other technological systems, as well as the visibility of auroras at specific geographical latitudes.

By using this scale, NOAA aims to provide clear warnings and timely information to stakeholders, ensuring preparedness and mitigation during significant solar events.

Now let's go back in time to the 19th century to explore the largest solar storm ever recorded and its impact on Earth.

It started like any other morning. Richard Carrington climbed the steps leading to an amateur observatory housed at his rural London estate, cranked open the shuttered dome and aimed a large brass telescope at a clear, blue sky.

He recorded the moment — 11:18 a.m., Sept. 1, 1859 — and then, as the sun came into view, began to sketch a group of large sunspots.

As he did, two points of light emerged, intensified and bloomed right before his eyes. Five minutes later, the blinding flares were gone. Although he didn't yet realize it, Carrington had witnessed what would become known as the largest solar flare in modern history.

The white-light solar flare, which someday would bear Carrington's name, was actually a magnetic explosion on the sun's surface.

It was so powerful that it briefly outshone the sun and, within a few hours, caused brilliant red, green and purple lights in the sky to erupt all over Earth (such light shows are colorful and common side effects of solar flares with coronal mass ejections).

It also supercharged telegraph cables that shocked operators, set telegraph paper afire and, in some cases, transmitted messages even when the lines were disconnected from their batteries.

Although there's still evidence of solar material erupting frequently on the sun, none have reached the magnitude of the 1859 event. But what if one did?

We have some idea based on lesser solar flare explosions that produced clouds of charged particles that have crashed into Earth's magnetic field, causing the field to waver in what researchers call a "geomagnetic storm." [source: NOAA]

In February 2011, for example, a solar storm interrupted GPS signals for several minutes, which could potentially have spelled disaster for commercial airplanes or ships relying on GPS guidance systems to land or dock during that time. [source: NASA]

Over a decade afterward, on April 21, 2023, a powerful solar event sent a fast-moving burst of plasma toward Earth, causing a severe geomagnetic storm two days later.

This storm disrupted power, communication systems and satellite functions. It also created brilliant auroras. Monitored by NOAA's DSCOVR spacecraft, this was the third major storm of its kind in the current solar cycle, following similar events in 2021 and earlier in 2023.

Tech Interference

If a "Carrington-sized" solar flare were to hit Earth today, it would emit X-rays and ultraviolet light, which would reach Earth's atmosphere and interfere with electronics, as well as radio and satellite signals.

It would also cause a solar radiation storm, which could potentially be deadly to astronauts not fully equipped with protective gear and unprotected by Earth's atmosphere.

Finally, a cloud of charged particles (that coronal mass ejection we mentioned earlier) would bump against Earth's magnetic field. Such an event would mean outages that would decommission everything from cell phones and computers to automobiles and airplanes. Cities would lose power for weeks and, potentially, months — and many activities necessary to daily life would no longer be possible.

Take a trip to refuel at a gas station, for example. Simply using a credit or debit card to pay for a few gallons of gas requires a satellite transaction, and creating one would no longer be possible.

The potential consequences of a large-scale solar flare hitting Earth have scientists scrambling to develop an early warning system and new solar flare detection methods, much like their predecessors once learned to forecast deadly tornadoes and other weather events. Someday, we might just have solar flare warnings alongside hurricane warnings and thunderstorm watches.

As the old saying goes, if you stay ready, you don't have to get ready. If you're concerned about how to safely make it through a massive solar storm, here are some steps you can take for peace of mind:

This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.