Scientists struggle to explain a new Martian light show.
Rather than little green men, the astronauts who put their boots on Martian ground are more likely to be greeted by green-streaked skies.
Scientists have known for more than 15 years that auroras, vibrant light shows in the atmosphere, exist on Mars. The planet’s auroras were found in small spots that seemed to sprout from the ground like mushrooms. The light canopies they formed are thought to come from what’s left of a magnetic field that decayed billions of years ago.
But researchers have just seen a new gigantic aurora on Mars unlike any other previously observed. They’re calling the phenomenon a “sinuous discrete aurora” to describe its enormous wormlike shape: a glowing twisted band of ultraviolet light stretching thousands of miles from the dayside, which faces the sun, to the back of the planet.
A United Arab Emirates Space Agency probe orbiting Mars, known as Hope, took the picture using an ultraviolet spectrometer device. The discovery raises new questions about Mars’ atmosphere, the composition of its ancient magnetic field, and the effects of solar wind — the gases flowing off the sun that make up so-called “space weather.”
When the Hope probe arrived at Mars last year, mission leaders soon realized its distance from the planet afforded them an opportunity to essentially “zoom out” and study the planet on a broad scale. After the first few images came from the 3,000-pound, SUV-sized spacecraft, they decided to home in on auroras, said Hessa Al Matroushi, who heads the mission, in a statement.
What scientists have seen in Hope’s snapshots has blown them away, said Rob Lillis, a planetary space physicist and Emirates Mars Mission collaborator based at the University of California, Berkeley. Since November, the team has seen several more instances of the wormlike lights, he said.
Most people associate auroras with the Northern Lights, a brilliant light show sometimes visible on Earth at night near the North Pole. A similar effect happens near Antarctica as well. Electrons that are shot out of the sun during solar storms travel along magnetic field lines at the planet’s poles into the atmosphere, interacting with the air.
