JWST finds ‘dark beads’ and wonky star patterns in Saturn’s sky: ‘These features were completely unexpected’

For a planet already famous for its beauty and mysteries, Saturn just became even more enigmatic.

Fresh observations from the James Webb Space Telescope (JWST) — the most detailed yet of the planet’s upper atmosphere — reveal “dark beads” scattered through Saturn’s glowing auroras and a star-shaped pattern with two arms mysteriously missing. Nothing like these features has ever been seen on another world.

“These features were completely unexpected and, at present, are completely unexplained,” Tom Stallard, an astronomer at Northumbria University in the U.K. who led the study, said in a statement.

Scientists say studying these oddities could reveal important clues about how Saturn’s magnetic bubble exchanges energy with its atmosphere, a process that powers the planet’s shimmering auroras.

The findings were presented last week at the Europlanet Science Congress–Division for Planetary Sciences meeting in Helsinki, Finland.

A new puzzle in Saturn’s atmosphere

To capture the images, a team of 23 scientists from the U.K., U.S. and France used JWST to observe Saturn for 10 continuous hours, roughly a full day on the fast-spinning giant, on Nov. 29, 2024. They tracked infrared light from hydrogen ions and methane, both of which offer valuable clues about chemistry and motion in the planet’s skies.

About 680 miles (1,100 kilometers) above the clouds, the team spotted a chain of dark, bead-like patches embedded in Saturn’s auroras. These beads resembled tiny holes in the light, staying stable for hours and drifting only a few degrees over the course of the day, the new study reports.

Animation of Dark Beads in Saturn’s Ionosphere – YouTube

Watch On

Some 310 miles (500 kilometers) lower, in the stratosphere, JWST revealed a sprawling star-shaped feature extending from the north pole toward the equator. Instead of six symmetrical arms, like a snowflake, only four reached outward — leaving two conspicuously missing and creating a lopsided star.

Montage of Star Arms in Saturn’s Stratosphere – YouTube

Watch On

Together, the beads and star arms painted a bizarre, layered portrait of Saturn’s skies. Intriguingly, the brightest “arm” of the star lined up directly with the darkest bead above it. “But it’s not clear at this point whether they are actually linked or whether it’s just a coincidence,” Stallard said in the statement.

The researchers considered whether the beads might be caused by icy particles raining in from Saturn’s so-called “E-ring,” which is constantly replenished by geysers from the moon Enceladus. But the E-ring is too smooth and uniform to produce such patchy features, the study notes.

Instead, the dark beads may be the result of winds colliding in Saturn’s upper atmosphere, creating turbulent zones that appear as dim patches in the aurora.

Intriguingly, when researchers mapped the star-shaped arms, they found the arms appeared to line up with the corners of Saturn’s mysterious hexagon, which is a massive six-sided cloud pattern at the planet’s north pole. First spotted by NASA’s Voyager spacecraft in the 1980s, the hexagon has long puzzled scientists, and the new findings suggest it may be linked to these strange upper-atmosphere features.

Saturn’s upper atmosphere is so faint that it has long been one of the hardest regions in the solar system to study. Even NASA’s Cassini spacecraft, which orbited Saturn for 13 years, couldn’t spot features like these. By detecting emissions thousands of times fainter than what ground-based telescopes can see, the JWST has opened an entirely new window into Saturn’s mysterious skies, scientists say.

“JWST’s incredible sensitivity has revolutionised our ability to observe these atmospheric layers, revealing structures that are completely unlike anything we’ve seen before on any planet,” Stallard said in the statement.

With Saturn now near its equinox, a seasonal milestone that comes only once every 15 Earth years, when sunlight shines directly over the equator, scientists are eager to see how the beads and star arms evolve. Shifting sunlight could reshape these patterns as the northern hemisphere moves into autumn, so JWST observations are high on the researchers’ wish list.

For now, the strange beads and missing arms remain unsolved, but thanks to JWST, astronomers finally have the images — and the mysteries — to chase.

A study about these results was published in late August in the journal Geophysical Research Letters.