In the latest image of Saturn taken by the National Aeronautics and Space Administration’s (NASA) Hubble Space Telescope, the appearance of rays on the planet’s rings heralded the start of a new “ray” season, according to a NASA statement. Scientists will look for clues to explain the cause and nature of the rays, the statement said.
The suspected culprit of the rays is the planet’s changing magnetic field, the statement said. Planetary magnetic fields interact with the solar wind to create an electrically charged environment.
On Earth, when these charged particles hit the atmosphere, it can be seen in the Northern Hemisphere as the aurora borealis, or northern lights, NASA said. Scientists think the smallest dust-sized particles of the ice ring may also become charged, temporarily levitating those particles above the rest of the larger ice particles and boulders in the rings, NASA said.
Like Earth, Saturn is tilted on its axis and thus has four seasons, although due to Saturn’s much larger orbit, each period lasts about seven Earth years, the space agency said.
The equinox occurs when the rings are tilted with their edge toward the Sun
The rays disappear when Saturn’s summer or winter solstice approaches, which is when the sun appears to be at either its highest or lowest latitude, respectively, in the planet’s northern or southern hemisphere, the space agency said.
As Saturn’s northern hemisphere autumnal equinox approaches on May 6, 2025, the rays are expected to become increasingly prominent and observable, the statement said.
The latest image taken by Hubble heralds the start of Saturn’s “ray season” with the appearance of two blurry rays in the B ring, one of Saturn’s rings, the fleeting features don’t last long, but more will appear as the planet’s autumnal equinox approaches, the statement said.
Ring rays were first observed by NASA’s Voyager mission in the early 1980s. The transient, mysterious features may appear dark or bright depending on lighting and viewing angles, the statement said.
NASA Senior Planetary Scientist Amy Simon, head of the Hubble Outer Planet Atmospheres Legacy (OPAL) program, said: “With the Hubble OPAL program building an archive of data on the planets of the outer solar system, we will have more time to study. Saturn’s rays this season than ever before.”
NASA’s Hubble Space Telescope gets time to observe Saturn every year thanks to the OPAL program, and the dynamic gas giant planet has always shown something new, the space agency said.
Saturn’s last equinox occurred in 2009, when the Cassini spacecraft orbited the gas giant planet for a detailed survey, the agency said in a statement. With the Cassini mission completed in 2017 and the Voyager spacecraft long gone, Hubble continues to work on long-term monitoring of changes to Saturn and other outer planets, the space agency said.
“Despite years of excellent Cassini observations, the exact start and duration of the jet season is still unpredictable, much like predicting the first storm during hurricane season,” Simon said.
While the other three gas giant planets in our solar system also have ring systems, nothing compares to the prominent rings of Saturn, making them a laboratory for the study of jet phenomena, the statement said.
Whether the rays can or do occur on other ringed planets is currently unknown, NASA said. “It’s a fascinating magic trick of nature that we only see on Saturn – at least for now,” Simon said.
Hubble’s OPAL program will add both visual and spectroscopic data in wavelengths of light from ultraviolet to near-infrared to Cassini’s archive of observations, NASA said. Scientists expect to put these pieces together to get a more complete picture of the jet phenomenon and what it reveals about ring physics in general, the statement said.
