A brilliant display of green, purple, and pink lights will brighten the skies for stargazers in North America on Saturday and Sunday night. This stunning effect, known as the Northern Lights or aurora borealis, occurs when energized particles from space hit the Earth’s atmosphere.

The National Oceanic and Atmospheric Administration (NOAA) reports that both the northern United States and much of Canada will offer prime views of this natural phenomenon. For those located directly under the aurora, the spectacle will be most vivid. However, viewers as far as 1000 km away can still witness the light show.

The optimal times for viewing are just after sunset or just before sunrise. During the day, the aurora remains invisible. NASA explains that these lights result from space weather events, where high-energy particles collide with atmospheric gas atoms near the magnetic pole.

The current geomagnetic storm is forecasted to peak on Saturday night, presenting an excellent opportunity for spectators, per NOAA. For those away from the poles, observing such displays can be a rare experience.

In North America, the best seasons for viewing auroras are March and November, though scientists have yet to fully understand why. Typically, these lights are observed in Earth’s highest latitudes, including regions in Russia, Norway, Sweden, and territories like Greenland and Alaska.

“For many people, the aurora is a beautiful nighttime phenomenon that is worth traveling to arctic regions just to observe,” says NOAA. “It is the only way for most people to actually experience space weather.”