Mars' sky gets a mysterious green aurora resembling a giant worm

The astronauts are more likely to be greeted by green-streaked skies than little green men.

There are vibrant light shows in the atmosphere of Mars. There were small spots on the planet that looked like mushrooms. The light canopies they formed are thought to have come from a magnetic field that decayed billions of years ago.

Researchers have just seen a new gigantic aurora on Mars. They call the phenomenon a "sinuous" and "wormlike" form of the solar system, because it stretches thousands of miles from the day side to the back of the planet.

The picture was taken by the United Arab Emirates Space Agency probe, known as Hope. The discovery raises new questions about the atmosphere of Mars, the composition of its ancient magnetic field, and the effects of solar wind.

A snapshot from the United Arab Emirates' Hope orbiter shows a new green wormlike aurora wrapping from the dayside of the planet to the nightside. Credit: Emirates Mars Mission

When the Hope probe arrived at Mars last year, mission leaders realized they had an opportunity to study the planet on a broad scale. Hessa Al Matroushi, who heads the mission, said in a statement that after the first few images came in, they decided to home in on the Auroras.

Rob Lillis, a planetary space physicist and Emirates Mars Mission partner based at the University of California, Berkeley, said that what scientists have seen in Hope's snapshots has blown them away. He said that the team has seen several more instances of the lights.

The Northern Lights are a brilliant light show that can be seen at night near the North Pole. There is a similar effect near the ocean. During a solar storm, the sun shoots out particles that travel along magnetic field lines at the planet's poles into the air.

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Auroras were mysterious for the longest time on Earth before we realized that they were actually space weather and high-energy streams of electrons coming from the sun.

Electrons follow magnetic field lines. Why does the one region of Mars look like a twisted worm?

There is something funny going on with the complex array of magnetic field lines behind Mars.

The mystery researchers want to solve it using a combination of spaceships run by NASA, the European Space Agency and the U.S. space program.

Mars Maven Credit: NASA

Mars Express Credit: ESA

NASA launched its Mars Maven mission. Mars Express began operations in 2004. Sometimes the probes swoop by at less than 200 miles away. The lowest point of the Hope is more than 12,000 miles away.

The distance gave the Emirates a distinct advantage. For the first time, scientists were able to see Mars at different times of the day and in different seasons. The other probes may have taken pictures of tiny parts of the massive wormlike Auroras before, but they only captured the tip of the iceberg.

The next step in the study will be for NASA and the European Space Agency to measure the electrons moving toward Mars during a solar storm. Hope will take pictures of the lights.

If we could get simultaneous measurements of both the cause and the effect, that would be the holy grail.