We can finally predict when Mars' skies will glow green with auroras, scientists say

Mars may be known as the Red Planet, but under the right cosmic conditions, its skies shimmer emerald with auroras — and for the first time, scientists think they can predict the spectacle.

Being able to predict Martian auroras, which result from solar storms that also unleash harmful radiation, could provide future astronauts with crucial warning and time to take cover, scientists say.

Auroras occur when charged particles from the sun slam into a planet's atmosphere and collide with atoms and molecules there, leading to a glow. On Earth, our magnetic field funnels those particles toward the poles, giving rise to the famous northern and southern lights. But Mars lost its global magnetic field long ago, a change that also helped transform it from a wet world into the dry planet we see today. With no shield to steer solar particles, the entire nightside sky can glow with diffuse green light, caused by oxygen atoms less than 60 miles (about 100 kilometers) above the surface.

In March 2024, NASA's Perseverance rover made skywatching history by capturing the first visible-light aurora on Mars, marking the first time such a phenomenon had been observed from the ground of another world.

Last week at the Europlanet Science Congress–Division for Planetary Sciences (EPSC–DPS) meeting in Helsinki, Finland, Elise Knutsen, a postdoctoral researcher at the University of Oslo, reported a second detection and described new tools her team developed to forecast when auroras will appear.

"The fact that we captured the aurora again demonstrates that our method for predicting aurorae on Mars and capturing them works," Knutsen said in a statement.

Unlike on Earth, where aurora forecasting benefits from decades of data, predicting Martian auroras is still a trial-and-error science. As part of the new study, Knutsen and her team programmed Perseverance's cameras to watch the sky after solar eruptions known as coronal mass ejections (CMEs) blasted in the direction of Mars. These massive outbursts hurl billions of tons of charged particles into space — and the faster the CME, the more likely it is to spark an aurora.

But rover observations must be scheduled about three days in advance, as mission teams on Earth need time to plan, validate and transmit commands to Mars. This forces researchers to make educated bets on which storms are promising enough to target, according to the statement.

Between 2023 and 2024, the team tried eight times. The first attempts came up empty because the CMEs weren't strong enough. Later, however, by focusing on faster, more intense storms, the researchers succeeded in capturing two instances of glowing green auroras, according to the statement.

Still, not every powerful CME produced a lightshow. "Statistically there is also a degree of randomness to these things, so sometimes we're just unlucky," Knutsen said in the statement.

"Predicting the aurora on Earth down to minute precision isn't an exact science either."