Hubble Space Telescope captures 'spokes' moving across Saturn's rings

According to CNN, Saturn's rings appear to be moving in "spokes" as seen by NASA's Hubble Space Telescope. This phenomena marks the beginning of the planet's fall equinox in its northern hemisphere. It will be the equinox on May 6, 2025.

NASA, ESA, and Amy Simon (NASA-GSFC); Alyssa Pagan, image processing (STScI)

Although the cause of the spokes is yet unknown, the planet's changing magnetic field is the "suspected culprit for the spokes," according to NASA. "Solar wind and planetary magnetic fields combine to produce an electrically charged environment." The space agency likens the occurrence to Earth's northern lights.

Based on the prior data from Voyager and Cassini, which was a designated Saturn probe, NASA is hopeful that Hubble's new data will either corroborate or disprove this notion. According to Amy Simon, a senior planetary scientist at NASA, "despite years of great monitoring by the Cassini mission, the precise onset and duration of the spoke season is still unexpected, similar to anticipating the first storm during hurricane season."

In the 2000s, the spokes were last noticed. Saturn has seasons, much like Earth does, however because of Saturn's longer orbit than Earth's, each season lasts for around seven years. As the planet approaches its equinox, when the rings are angled toward the sun, the spokes become visible. Near Saturn's summer or winter solstices, the spokes vanish.

The phenomena may potentially occur on other ringed planets like Uranus and Neptune, according to NASA, although it has only been seen on Saturn thus far. For the time being, Simon said, "It's a fascinating magic trick of nature we only witness on Saturn."