Evrim Yazgin
Cosmos science journalist
The vast expanse of space is throwing up more unexplained phenomena and bizarre cosmic happenings which have astronomers dumbfounded.
As they say, if you love it, put a ring on it!
Saturn is famous for its rings which are the most impressive in the solar system.
But proximity and notoriety hasn’t brought with it comprehension. There are still mysteries emanating from Saturn’s rings.
In the early 1980s, NASA’s Voyager mission first revealed transient features on the rings of the solar system’s second largest planet. These “spokes” or “smudges”, as they became known, have confounded scientists since.
Now, the Hubble Space Telescope (yep, it’s still giving us the goods despite being usurped by the James Webb Space Telescope) has released images which herald the start of another “spoke season” for the gas giant.
Because of Saturn’s tilt, it like Earth has four seasons. The planet’s equinox occurs when its rings are edge-on to the sun. The spokes disappear near summer or winter solstice. May 6, 2025 marks the beginning of Saturn’s autumnal equinox – and the spokes are believed to become increasingly prominent until then.
Read more: A dozen new moons have been discovered spinning around Jupiter
The cause of the “smudges” on Saturn’s rings is unknown, but the most likely candidate is the planet’s variable magnetic field. It is thought that the dusty, icy particles in Saturn’s rings may become charged as the magnetic field interacts with them, temporarily raising those particles above the larger objects in the rings.
“It’s a fascinating magic trick of nature we only see on Saturn – for now at least,” comments NASA senior planetary scientist Amy Simon.
Similar processes wherein the planetary magnetic field charges surrounding particles causes the aurora borealis and australis on Earth.
“Thanks to Hubble’s OPAL [Outer Planet Atmospheres Legacy] program, which is building an archive of data on the outer solar system planets, we will have longer dedicated time to study Saturn’s spokes this season than ever before,” says Simon, who is head of OPAL.
From the sublime to the ridiculous: the solar system’s newest ring system shouldn’t exist.
Astronomers have discovered a new ring system around a dwarf planet, Quaoar. But the catch is that the ring system orbits the planet much further than is typical – seven times the dwarf planet’s radius (for comparison, Saturn’s rings lie within three of Saturn’s radii).
Normally, material orbiting so far out should evolve into a moon, not a ring system.
“It was unexpected to discover this new ring system in our Solar System, and it was doubly unexpected to find the rings so far out from Quaoar, challenging our previous notions of how such rings form,” says Professor Vik Dhillon from the University of Sheffield.
Read more: Researchers crack open secret of how cracks form on Pluto’s moon Charon
Quaoar has a diameter of approximately 1,100 kilometres (roughly half the size of Pluto).
The dwarf planet was discovered in 2002 and shows signs of ice volcanism. It already has a little moon friend called Weywot which measures 170 kilometres across.
Researchers found the ring system through occultation – when Quaoar passed in front of a distant star, the rings dimmed the star’s light slightly – using the world’s largest optical telescope, the Gran Telescopio Canarias on La Palma, the most north-westerly island of the Canaries off the coast of Spain.
Their results are published in the journal Nature.