Hubble is investigating mysterious “spokes” in Saturn’s rings

Saturn is famous for its beautiful rings, but these rings have a strange feature: “spokes” which appear intermittently. These spots in the rings can be light or dark and can look like blobs or like lines stretching radially outward from the planet, and they appear in a regular cycle related to the planet’s equinox. Now, the Hubble Space Telescope has the opportunity to study these oddities of the rings in more detail and researchers hope they can learn more about what causes these features.

The spokes were first noticed by the Cassini mission to Saturn in the 1980s, and since then they have been seen just before and after the equinox: the time at which day and night are of equal length across the planet because the sun is directly over the equator. On Earth, we experience two equinoxes each year, and the same is true for Saturn — but because Saturn is further out in its orbit and its year is much longer, its equinoxes occur just once every 15 Earth years.

Saturn’s next autumnal equinox is coming up on May 2025, so researchers are using Hubble to observe the planet and its rings at this key time. “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,” said Amy Simon, head of the Hubble Outer Planet Atmospheres Legacy (OPAL) program, in a statement.
Hubble is investigating mysterious “spokes” in Saturn’s rings