Saturn’s rings are going through some unusual changes and NASA are in the dark about what actually causes the phenomenon.
Around every 15 years or so, large smudges - dubbed ‘spokes’ by NASA - appear on Saturn’s rings and scientists remain baffled by what causes them, despite them first being spotted back in the 1980s.
New images from the Hubble Telescope have shown that, once again, ‘spoke season’ is underway - and scientists are hopeful that the new shots will help them gain a deeper understanding of exactly what is going on.
NASA planetary scientist Amy Simon said: “Thanks to Hubble's OPAL 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.”
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The unusual marks have been given the nickname ‘spokes’ as the pattern they make resembles the spokes on the wheel of a bicycle.
The markings only show up in the preceding and following equinoxes on Saturn - so the planet’s equivalent of spring and autumn.
Much like our planet, Saturn is tilted on its axis so has four seasons, but, because it has a much larger orbit, its seasons last a lot longer: around seven Earth years.
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Saturn’s autumn equinox arrives in May 2025 but the smudges start to show up around four years prior, which is why they have been picked up by the telescope.
NASA says as the equinox draws closer, the spokes are expected to become clearer.
The spokes were first spotted by NASA Voyager probes which flew past the sixth planet from the sun back in 1980 and 1981.
The planet’s last equinox was back in 2009 when NASA’s Cassini spacecraft was still orbiting and collecting data - but its mission came to a close in 2017, meaning Hubble is hoping to pick up where it left off.
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But four decades on from their first sighting, and despite data from Cassini, NASA is still unclear on why or precisely when ‘spoke season’ starts.
Simon added: “Despite years of excellent observations by the Cassini mission, the precise beginning and duration of the spoke season is still unpredictable, rather like predicting the first storm during hurricane season.”
In 2005, NASA said the spokes were most likely related to Saturn’s magnetic field but as yet there is no solid explanation about what causes them.
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One theory is that Saturn’s magnetic fields interact with the solar wind, creating an electrically charged environment. NASA believes this may cause the smallest icy ring particles to also become charged ‘which temporarily levitates those particles above the rest of the larger icy particles and boulders in the rings’.
Claire Reid