Skip to main content

Mars once had rings of its own, new research suggests

Saturn is the planet in our solar system that’s famous for its beautiful rings, but it may once have had competition from our neighbor, Mars.

New research from the SETI Institute and Purdue University suggests that millions of years ago, Mars may have had rings of its own.

The new research provides evidence in support of the ring hypothesis by looking at the unusual orbits of Mars’ moons. Both of its two moons, Phobos and Deimos, orbit in a similar plane to its equator, but Deimos orbits at a slight angle, tilted by two degrees.

“The fact that Deimos’s orbit is not exactly in-plane with Mars’ equator was considered unimportant, and nobody cared to try to explain it,” lead author
Matija Ćuk, a research scientist at the SETI Institute, said in a statement. “But once we had a big, new idea and we looked at it with new eyes, Deimos’ orbital tilt revealed its big secret.”

Rendering showing a planetary ring system over Mars.
A rendering shows a planetary ring system over Mars, demonstrating either the formation or destruction of its moons, Phobos and Deimos. Kevin Gill

Scientists already knew that Mars could develop a ring in the far future, as its fragile moon Phobos will be pulled toward the planet over millions of years and ripped apart by its tidal forces to form a ring of rocky particles that will encircle it.

This is estimated to happen in approximately 70 million years’ time. It may even be possible that this is part of an enormous cycle in which the rocky matter that constitutes the moon is pulled apart and pushed back together, with Mars oscillating between having rings and moons.

Ćuk and his colleagues argue that the tilt of Deimos must have arisen from the presence of a second massive moon in addition to rings. This second massive moon was the “grandparent” of Phobos. It was 20 times Phobos’ mass and existed more than 3 billion years ago. Since then, this body has undergone two more cycles of destruction and reformation as rings and moon.

This research remains theoretical, but there may be experimental evidence available within a few years if the Japanese Space Agency sends its planned spacecraft to Phobos. Samples from Phobos could reveal more about the origin of the moons and the history of Mars.

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
It’s been 2 years since the Perseverance rover landed on Mars
This image of the floor of Jezero Crater was taken by one of the Navcam imagers aboard NASA’s Perseverance Mars rover on Feb. 5, the 698th Martian day, or sol, of the mission.

Today marks the second anniversary since the rover Perseverance landed on the surface of Mars on February 18, 2021. The nail-biting descent and landing process was followed around the world, and was particularly memorable because of the spectacular video taken from both the rover and its descent stage showing the touchdown onto the red planet.

In the two Earth years since Perseverance arrived on Mars, it has collected samples of rock and built a sample depot, deployed the Mars helicopter Ingenuity, created oxygen from the carbon dioxide atmosphere, recorded the sounds of Mars for the first time, trundled along the floor of the Jezero crater and made its way toward the site of an ancient river delta, and taken some stunning images.

Read more
Ingenuity helicopter helps researchers learn about dust on Mars
The Ingenuity helicopter is pictured on the surface of Mars.

One of the big challenges of Mars exploration is something very small: dust. Fine dust covers much of the martian surface, and high winds and low gravity mean the dust is easily whipped up off the surface, covering solar panels and gumming up components. The Ingenuity helicopter has had its own problems with dust on its solar panels, limiting the amount of power it could draw from the sun.

Now, researchers have used data from Ingenuity to understand more about how dust moves in the martian air, learning about the dynamics of dust, which could help future missions deal with this ongoing problem.

Read more
How to see Mars at its brightest at opposition this week
Finder chart for Mars on 8 December.

Stargazers in the northern hemisphere are in for a treat this week as Mars has reached its closest point to Earth, giving the best view of the red planet until the 2030s. Mars made its closest approach to Earth on the night of November 30 to December 1, but the best views are yet to come as the planet reaches a point called opposition on the night of December 7 to December 8. Opposition is when Mars is directly opposite the sun as seen from Earth, which means this is when Mars will be at its brightest.

Mars Opposition - December 2022

Read more