It’s incredible to think that the sun, roughly 93 million miles away, can mess with our power grids here on Earth and paint our night skies with ribbons of green and red. But that’s exactly what happens when a coronal mass ejection (CME) is unleashed!

A CME is one of the most dramatic events our sun can produce. Imagine a colossal explosion on the sun’s surface, billions of tons of charged particles hurled into space at a speed of millions of miles per hour. That’s a CME. It happens when the Sun’s tangled magnetic fields suddenly snap and realign, blasting plasma and magnetic energy out into the solar system.

When one of these eruptions is aimed toward Earth, the effects can be felt far beyond the upper atmosphere. As the wave of solar material collides with Earth’s magnetic field, it can trigger powerful geomagnetic storms.

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Those storms can cause dazzling auroras that reach much farther south than usual, sometimes visible across much of the continental United States. But they can also disrupt satellite communications, GPS and even power grids if the storm is strong enough.

CMEs are part of the sun’s natural rhythm, becoming more frequent during peaks in the solar cycle, which lasts about 11 years. Space agencies like NASA and NOAA’s Space Weather Prediction Center keep a close eye on the sun to give us warning when one’s headed our way.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.