Giant solar storms can delight us by causing brilliant lights in the night sky, but they can also be destructive. Scientists are working together to be able to predict space weather and keep us safe.
Space weather is the term used for a whole chain of phenomena and events that begins with the solar wind and solar storms, and includes their effects on Earth’s atmosphere, satellites, and ground-based systems.
The Sun continuously gives off energy as light and heat, and it sends out large amounts of matter as charged particles—the solar wind. There are often giant eruptions on the Sun that hurl vast amounts of both energy and matter out into space. These events are called solar storms. Just like on Earth, where storms are discussed as part of our weather, solar storms are a part of space weather.
The Sun is constantly emitting particles into space. This video shows particles streaming into space, called the solar wind, during an eclipse. (Shadia Habbal)
Occasionally, there are large eruptions on the sun, known as flares, prominences, or Coronal Mass Ejections, which hurl large amounts of matter into space. This is a large eruption captured by NASA's Solar Dynamics Observatory on February 24, 2011. (Goddard Space Flight Center)
Ordinarily, Earth’s magnetic field protects us from the solar wind by deflecting the charged particles around Earth toward the North and South Poles. These particles energize elements in our atmosphere, resulting in the bright celestial lights we know as auroras: aurora borealis, or the northern lights, near the North Pole; and aurora australis, the southern lights, near the South Pole. During a solar storm, when Earth is bombarded with billions of tons of extra particles, we see extraordinarily bright and beautiful auroras that can also extend closer to the equator.
An artist’s rendition of solar wind being diverted around Earth by our magnetic field. (NASA)
The northern lights were seen over Alaska the night of February 16, 2017, at the Poker Flat Research Range north of Fairbanks. (NASA/Terry Zaperach)
While solar storms can create great beauty, they can also be destructive. Solar storms can disrupt power grids and communications on Earth. Energetic particles from the Sun can interfere with both the flow of electric current in wires and the transmission of radio waves through the air. Often, storms produce surges in the power grid and static on the radio. If a storm is strong enough, power grids can be overloaded and radio signals drowned out.
The 1859 Carrington Event is the most famous disruption of this kind. This solar storm caused red auroras as far south as Cuba, and severe interruptions in global telegraph communications. The storm even sparked fires and caused electrical shocks to some telegraph operators. There have been other notable disruptions since then. The Great Storm in May 1921 caused the lights on Broadway to dim and temporarily shut down the New York Central Railroad. At the height of the Cold War in May 1967, a solar storm almost started a war when the US government believed the Soviets had jammed radar and radio communications. (Fortunately, the Air Force notified the government that there had been a space weather event before an airstrike was ordered!). In 1989, a storm hit Earth that created auroras in Texas and Florida and overwhelmed Canada’s power grid, cutting power to six million people. In 2017, solar activity caused a storm that led to a high-frequency radio blackout for over eight hours on the same day that Hurricane Irma was passing through the Caribbean.
Of course, anything outside the region protected by Earth’s magnetic field is at extreme risk from solar activity. Orbiting satellites, for instance, have very little protection: in 2022, a storm destroyed 40 of SpaceX’s Starlink satellites. Spacecraft impacted by storms can experience temporary operational anomalies, damage to critical electronics, degraded solar arrays, and damage to surface-to-orbit and surface-to-surface communications. On top of that, exposure to particle radiation can threaten astronauts’ lives.
A sunspot is an area on the sun that has increased activity. Scientists monitor these closely, as sunspots often turn into solar eruptions. This video shows a sunspot as it rotates into view, creating a solar flare then an even larger large coronal mass ejection that causes aurora on Earth, before rotating out of sight. (NASA/GSF)
It is becoming urgent to predict space weather as we increase our technological reliance on the electrical grid and as NASA pushes farther out into space. To this end, NASA is working with the National Oceanic and Atmospheric Administration (NOAA). Together, they have a fleet of satellites that monitor the Sun constantly and provide real-time data to space weather forecasters. Much like how we forecast thunderstorms and rain showers, NOAA’s Space Weather Prediction Center runs simulations and can make predictions about when a storm will arrive at Earth. It then alerts appropriate groups so that power companies, airlines, and others can take needed precautions.