Nav: Home

Saturn's moon Mimas, a snowplough in the planet's rings

June 11, 2019

The Solar System's second largest planet both in mass and size, Saturn is best known for its rings. These are divided by a wide band, the Cassini Division, whose formation was poorly understood until very recently. Now, researchers* from the CNRS, the Paris Observatory - PSL and the University of Franche-Comté have shown that Mimas, one of Saturn's moons, acted as a kind of remote snowplough, pushing apart the ice particles that make up the rings. The findings are the result of two studies supported by the International Space Science Institute and CNES, the French space agency, published simultaneously in June 2019 in Monthly Notices of the Royal Astronomical Society.

Saturn's rings are made up of ice particles whose orbital velocity increases the closer they are to the planet. The Cassini Division is a wide, dark band located between Saturn's two most visible rings, in which the particle density is considerably lower than that inside the rings. The researchers suspected a link between Mimas, one of Saturn's moons, and the band, since there is a region at the inner edge of the Division where the particles orbit around Saturn exactly twice as fast as Mimas. This phenomenon, known as orbital resonance, pushes the ice particles apart, producing a relatively narrow gap. Scientists from CNRS, the Paris Observatory - PSL and the University of Franche-Comté have now shown that Mimas may have moved closer to Saturn in the recent past, making the moon a kind of remote snowplough that widened the initial gap, giving it the 4500 km width it has today. If on the other hand the orbit of Mimas moved outwards, the particles would return to their original position, rather as if a snowplough were to reverse and stop pushing the snow, letting it spread out again. Using numerical simulations, the researchers calculated that Mimas must have migrated inwards by 9000 km over a few million years in order to open up the 4500 km gap that currently makes up the Cassini Division.

A natural satellite, such as the Moon, normally tends to move away from its planet rather than closer to it. In order to migrate inwards, a moon has to be able to lose energy, particularly by heating up, which would cause its internal ice to melt and weaken its outer crust. However, the state of Mimas' surface, which still bears the scars of relatively ancient meteorite impacts, does not tally with such a scenario. The researchers' second hypothesis, which remains to be confirmed, is that the loss of heat was shared out between Mimas and Enceladus, another of Saturn's moons, through orbital resonance. This would have caused the creation of the internal oceans that the Cassini spacecraft detected below the surface of both these bodies.

Today, Mimas has begun to migrate outwards again. According to the researchers' calculations, the Cassini Division is likely to take around 40 million years to close up again. Thanks to these findings, scientists may view the presence of gaps in the rings of an exoplanet as a clue that it could have moons with oceans.
-end-
*The researchers belong to the Institut de Mécanique Céleste et de Calcul des Éphémérides (Observatoire de Paris - PSL / CNRS), Institut UTINAM (CNRS / Université de Franche-Comté), Institut de Physique du Globe de Paris (CNRS / Université de Paris / IPGP / IGN), Laboratoire de Planétologie et Géodynamique (Université de Nantes / CNRS / Université d'Angers), Namur Institute for Complex Systems (Université de Namur), and the Jet Propulsion Laboratory (NASA).

CNRS

Related Saturn Articles:

What makes Saturn's atmosphere so hot
New analysis of data from NASA's Cassini spacecraft found that electric currents, triggered by interactions between solar winds and charged particles from Saturn's moons, spark the auroras and heat the planet's upper atmosphere.
New SwRI models reveal inner complexity of Saturn moon
A Southwest Research Institute team developed a new geochemical model that reveals that carbon dioxide (CO2) from within Enceladus, an ocean-harboring moon of Saturn, may be controlled by chemical reactions at its seafloor.
Saturn surpasses Jupiter after the discovery of 20 new moons
Move over Jupiter; Saturn is the new moon king. A team led by Carnegie's Scott S.
New SwRI study argues that Saturn's rings are actually not young
No one knows for certain when Saturn's iconic rings formed, but a new study co-authored by a Southwest Research Institute scientist suggests that they are much older than some scientists think.
Hubble reveals latest portrait of Saturn
The NASA/ESA Hubble Space Telescope's Wide Field Camera 3 observed Saturn on 20 June 2019 as the planet made its closest approach to Earth this year, at approximately 1.36 billion kilometres away.
Saturn's rings shine in Hubble's latest portrait
Saturn is so beautiful that astronomers cannot resist using the Hubble Space Telescope to take yearly snapshots of the ringed world when it is at its closest distance to Earth.
Saturn's moon Mimas, a snowplough in the planet's rings
The Solar System's second largest planet both in mass and size, Saturn is best known for its rings.
Deep learning takes Saturn by storm
A 'deep learning' approach to detecting storms on Saturn is set to transform our understanding of planetary atmospheres, according to UCL and University of Arizona researchers.
Close Cassini flybys of Saturn's ring moons
The properties of five small moons located close to Saturn's rings have been illuminated, thanks to data from the Cassini spacecraft's final orbits.
Saturn hasn't always had rings
In its last days, the Cassini spacecraft looped between Saturn and its rings so that Earth-based radio telescopes could track the gravitational tug of each.
More Saturn News and Saturn Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.