Of all the planets in our solar system, you would probably agree that Saturn can be considered the prettiest of them all. Its multiple rings of icy material and rock are composed of particles too small to see with the naked eye, but they make it a spectacular sight, even from Earth. It is the only planet with rings visible from Earth (Jupiter, Uranus and Neptune also have but we can’t see them).
Its rings are about 400,000 kilometers wide (about the distance between Earth and the Moon), but they do not represent a permanent feature, experts say. They are disappearing, slowly, but they will do so in 300 million years. This was demonstrated by a NASA investigation based on the observations of the Voyager 1 and 2 space probes made decades ago.
Why do you lose the rings?
The iconic rings are being pulled towards Saturn by gravity under the influence of the planet’s magnetic field.
Saturn’s rings are made of chunks of water ice that range in size from microscopic dust grains to rocks several meters across. The Cassini spacecraft, which arrived at Saturn in 2004, found that much of the material in Saturn’s E ring, a diffuse ring outside the bright main rings, was the result of jets of water emerging from the moon Enceladus.
The ring particles are caught in a kind of balance between the pull of Saturn’s gravity and their orbital speed: gravity pulls them to the planet, and orbital speed tries to fling them out into space. However, the rings are disappearing due to the electrification of dusty matter, something that is caused by disturbance from micrometeorites and ultraviolet radiation from the Sun.
a rain of rings
The particles, once electrified, align with Saturn’s magnetic field lines; in some parts of the rings, once charged, the balance of forces on these tiny particles changes dramatically; they get too close to the upper part of Saturn’s atmosphere and the planet’s gravity pulls them into its clouds. There they are vaporized.
“We estimate that this ‘ ring rain ‘ drains a quantity of water products that could fill an Olympic swimming pool from Saturn’s rings in half an hour,” said James O’Donoghue of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. . “On this alone, the entire ring system will be gone in 300 million years, but add to this the ring material measured by the Cassini spacecraft detected falling on Saturn’s equator, and the rings would be less than 100 million years old. ” This is relatively short, compared to Saturn’s age of over 4 billion years.”
They are ‘cosmically young’ , hence these rings, appearing sometime between 10 and 100 million years ago, while dinosaurs were still walking the Earth.
As there is still plenty of time for the rings to disappear, this is good news for us, as we will have the opportunity to see this fascinating feature of the second largest planet in the solar system, after Jupiter.
“We are lucky enough to be close enough to see Saturn’s ring system, which appears to be in the middle of its life, ” added O’Donoghue.
Referencias: O’Donoghue, J., Stallard, T., Melin, H. et al. The domination of Saturn’s low-latitude ionosphere by ring ‘rain’. Nature 496, 193–195 (2013). https://doi.org/10.1038/nature12049
J. E. P. Connerney Magnetic connection for Saturn’s rings and atmosphere First published: August 1986 Geophysical Research Letters DOI: https://doi.org/10.1029/GL013i008p00773
James O’Donoghue, Luke Moore, Jack Connerney, Henrik Melin, Tom Stallard, Steve Miller, Kevin H. Baines. Observations of the chemical and thermal response of ‘ring rain’ on Saturn’s ionosphere. Icarus, 2018; DOI: 10.1016/j.icarus.2018.10.027
