Skip to main content

Hubble snaps an image of dark spokes in Saturn’s rings

The Hubble Space Telescope is investigating something strange about the beautiful rings around Saturn. You might picture Saturn’s rings as perfectly smooth, but in fact, they have some strange dark spots that appear intermittently. These features, called spokes, look like dusty blots spread over the rings and appear for just a few rotations before disappearing again, with some periods having much more spoke activity than others.

These spokes were first observed over 40 years ago by the Voyager 2 spacecraft, but they continue to be something of a mystery. They seem to be linked to seasons on the planet, which are seven years long, and to the planet’s magnetic field. A newly released image taken by Hubble in October this year shows the spokes as dark patches on the rings, observed as part of a program called Hubble’s Outer Planets Atmospheres Legacy (OPAL), which tracks them as they move.

This photo of Saturn was taken by NASA's Hubble Space Telescope on October 22, 2023, when the ringed planet was approximately 850 million miles from Earth. Hubble's ultra-sharp vision reveals a phenomenon called ring spokes. Saturn's spokes are transient features that rotate along with the rings. Their ghostly appearance only persists for two or three rotations around Saturn. During active periods, freshly-formed spokes continuously add to the pattern.
This photo of Saturn was taken by NASA’s Hubble Space Telescope on October 22, 2023, when the ringed planet was approximately 850 million miles from Earth. Hubble’s ultra-sharp vision reveals a phenomenon called ring spokes.Saturn’s spokes are transient features that rotate along with the rings. Their ghostly appearance only persists for two or three rotations around Saturn. During active periods, freshly formed spokes continuously add to the pattern. NASA, ESA, STScI, Amy Simon (NASA-GSFC)

Now is a good time for observing the spokes, as Saturn’s autumnal equinox will occur in May 2025. In the past, researchers have observed a peak in spokes in the periods leading up to and following the equinox.  “We are heading towards Saturn equinox, when we’d expect maximum spoke activity, with higher frequency and darker spokes appearing over the next few years,” explained OPAL program lead scientist Amy Simon of NASA’s Goddard Space Flight Center in a statement.

Even though researchers have observed this link between the seasons and the spokes, the exact mechanism that causes them is still unclear. The features are huge, appearing on both sides of the planet and stretching so far across the rings that their size can be larger than the diameter of the Earth. Researchers believe that the spokes are related to solar wind interacting with the planet’s magnetic field.

“The leading theory is that spokes are tied to Saturn’s powerful magnetic field, with some sort of solar interaction with the magnetic field that gives you the spokes,” explained Simon.

But it’s still difficult to predict exactly when and where these spokes will appear, which is why the researchers are keen to use Hubble during this upcoming period.

Editors' Recommendations

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
Hubble images a pair of galaxies caught in the process of merging
This NASA/ESA Hubble Space Telescope image features Arp 122, a peculiar galaxy that in fact comprises two galaxies – NGC 6040, the tilted, warped spiral galaxy and LEDA 59642, the round, face-on spiral – that are in the midst of a collision.

After last week's image of the week from the Hubble Space Telescope showed a cluster of galaxies that appeared to be very close to each other but actually weren't, this week's image shows two images that are practically on top of each other. The two galaxies shown in the image below, NGC 6040 and LEDA 59642, are so close that they are interacting and have a shared name as a pair, Arp 122.

This NASA/ESA Hubble Space Telescope image features Arp 122, a peculiar galaxy that in fact comprises two galaxies – NGC 6040, the tilted, warped spiral galaxy and LEDA 59642, the round, face-on spiral – that are in the midst of a collision. ESA/Hubble & NASA, J. Dalcanton, Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA Acknowledgement: L. Shatz

Read more
Neptune isn’t really dark blue, new study demonstrates
Voyager 2 took this image as it approached the planet Uranus on Jan. 14, 1986. The planet's hazy bluish color is due to the methane in its atmosphere, which absorbs red wavelengths of light.

Among the most famous images taken by the Voyager spacecraft are those of Uranus and Neptune. When you think of these planets, you're likely imagining them based on the images taken by Voyager 2 in 1986 and 1989, which show the planets as pale greenish blue and royal blue respectively. But a new study shows that the two planets are a very similar color, both closer to a pale baby blue.

Constructing exact color images of space objects is challenging because of how spacecraft cameras typically work. Instead of capturing a color image, cameras typically take a series of black-and-white images using filters corresponding to different wavelengths. Image processors then layer together these black-and-white images to produce a color image.

Read more
Hubble captures a busy frame of four overlapping spiral galaxies
This image from the NASA/ESA Hubble Space Telescope features a richness of spiral galaxies.

This week's image from the Hubble Space Telescope shows a host of galaxies overlapping in a complex swirl. Four main galaxies are shown in the image, three of which look like they are practically on top of each other, but all is not as it appears in this case.

The largest galaxy in the image, located on the right, is NGC 1356, an elegant barred spiral galaxy similar to our Milky Way. It is also known as the Great Barred Spiral Galaxy due to the prominent nature of its bar, which is a bright structure at the center of the galaxy which is rich with stars. Near this galaxy appear two smaller spiral galaxies, LEDA 467699 and LEDA 95415, and off on the left side of the image is IC 1947.

Read more