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Weird things are happening on Mars again.

As space technology improves, our ability to understand the cosmos gets better and better. But the latest advancements in satellites and imaging systems also create new questions about the universe.

Case in point: NASA’s MAVEN space probe, which is orbiting Mars and studying its atmosphere, has uncovered two separate new mysteries in the Martian atmosphere. It detected a strange high-altitude dust cloud—the origin of which is unknown—as well as a dazzling aurora light show that’s much lower in the atmosphere than scientists anticipated.

First, the dust cloud. According to NASA, it extends from 93 miles (150 kilometers) above the planet’s surface to 190 miles (300 km). Not only did researchers not expect a dust cloud to be present at those altitudes, but they’re also unsure how exactly it got there.

“If the dust originates from the atmosphere, this suggests we are missing some fundamental process in the Martian atmosphere,” said Laila Andersson, one of the scientists working on MAVEN at the University of Colorado Boulder, in a press release.

University of Colorado An artist’s interpretation of MAVEN observing the strange “Christmas lights” on Mars.

Researchers have a few theories, assuming the dust didn’t originate from Mars itself. It could have drifted in from Mars’ moons, Phobos and Deimos, or from comet debris orbiting the sun. It also could have blown in with solar wind coming from the sun. Bruce Jakosky, the lead investigator, told New Scientist that MAVEN will conduct a flyby of Phobos to see if there’s any dust meandering away from it.

The second mystery is a bizarre aurora—similar to Earth’s northern lights—observed in a place (like the dust cloud) where scientists didn’t expect to find it.

“What’s especially surprising about the aurora we saw is how deep in the atmosphere it occurs—much deeper than at Earth or elsewhere on Mars,” said Arnaud Stiepen, another MAVEN team member at the University of Colorado. “The electrons producing it must be really energetic.”

The ultraviolet light show, which spans Mars’ northern hemisphere, was nicknamed the “Christmas lights” because it was detected right around Dec. 25 of last year. Aurorae are created when charged particles from the sun strike the atmosphere and cause the gases there to shine in cool colors.

Just last month, researchers admitted that they had no idea what was causing a recently detected plume over Mars. It could be linked to the dust clouds observed by MAVEN, although those were found in the planet’s northern hemisphere, while the mysterious plume was discovered in the southern hemisphere.