Why Did Saturn’s Rings Disappear on November 22nd?

Our solar system is made up of eight planets that can be classified under two groups: rocky planets and gas giants. Mercury, Venus, Earth, and Mars, the four closest to the Sun, are rocky planets; the gas giant planets include Jupiter, Saturn, Uranus, and Neptune, and they are significantly larger than the rocky planets.

Recently, the gas giant Saturn was in the news because astronomers observed that Saturn’s rings “disappeared” on November 22^nd, an occurrence that doesn’t happen frequently (1,2). In this brief article, we explain the phenomenon that took place on that day, why astronomers are interested in it, and how spectroscopy is being used to study the planet Saturn.

What is Saturn?

Saturn is the second-largest planet in the solar system, only behind Jupiter. It is characterized by its rings, which are notable when seen through a telescope. These rings are comprised mostly of dust, rocky debris, and ice particles (3). Saturn has a diameter about nine times that of Earth (3).Its surface ismade mostly of hydrogen and helium.Saturn is the least dense planet, and its average density is so low that it would float in water if a body of water large enough existed (3).

Saturn also has numerous moons orbiting it. Currently, astronomers have identified 146 moons orbiting the planet, with Titan being the largest and most notable (3). Saturn is also categorized by its short days and long years.A day on Saturn lasts approximately 10 hours and 33 minutes due to its rapid rotation, but a year on Saturn is the equivalent of 29.5 Earth years (so if you’re 30 years old, like yours truly, Saturn has only completed one orbit around the sun in your lifetime) (3).

Why did Saturn’s Rings “Disappear” in November?

First, it is important that the word “disappear” is defined here. Saturn’s rings didn’t disappear in the sense that they no longer exist or are not present. Instead, what happened is more of a celestial illusion where, from our vantage point, we cannot see the rings because of Saturn’s rings lining up with Earth (1). This phenomenon is called a ring plane crossing (1,4), which is defined as an astronomical event where Saturn’s axial tilt causes the rings to appear so thin they disappear from our point of view, and we cannot see them with ground-based telescopes (1,4). This occurrence normally happens once every 13–15 years (4). As a result, the next time this happens will be sometime in 2038 or 2039.

What studies are being conducted on Saturn?

Currently, spectroscopy is being used to reveal certain aspects about Saturn. First, spectroscopy is being used to help us understand more about its atmospheric composition, gases, and temperature structure. For example, the ultraviolet imaging spectrograph (UVIS) is being used to measured ultraviolet light from Saturn and its moons. By studying how sunlight (or starlight) is absorbed or scattered by gases in Saturn’s atmosphere, scientists identified constituents such as methane, ethane, acetylene, hydrogen, oxygen, and other compounds (5).

“The cool thing about UVIS is that we can see things that are invisible to other instruments," said Amanda Hendrix, a planetary scientist at the Planetary Science Institute and a UVIS team member who analyzes icy satellite data, according to NASA (5). "For example, UVIS can 'see' gases in the Saturn system that aren't seen by Cassini’s visible-light camera. The instrument can also see the dark, night side of the moons of Saturn, which stand out against the sky because they are bright at ultraviolet wavelengths."

Meanwhile, another instrument called the Composite Infrared Spectrometer (CIRS) is being used to measure infrared (IR) emissions from Saturn’s atmosphere (6). That helped build vertical and horizontal maps of temperature and gas abundances, giving insight into atmospheric structure (clouds, haze layers), weather, and seasonal changes (6).

Spectroscopy is also being used to understand the ring composition and structure better. Spectroscopic observations, especially in visible, near-infrared, ultraviolet, and infrared, show that Saturn’s rings are overwhelmingly dominated by water ice (7,8).

References

1. Saclao, C. Saturn’s Rings Disappear Tonight in Rare Cosmic Event. Yahoo.com. Available at: https://www.yahoo.com/news/articles/saturn-rings-disappear-tonight-rare-003442792.html?guccounter=1&guce_referrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8&guce_referrer_sig=AQAAAFY5reuuFqEouXvE2yLC6a80w67caVmn2iH9LjTf65q7EKgKQiP0JvNjksoeOK8OR17cxptC90EuKSqGZ9f5i2QTUmfUkQVA_gKQrXzEItvs6b9sre4TvLcZdXuI2JTbpo4ztffXO72Fp49b_czpucy5i9UXctfIZ_8QN40AOyzp (accessed 2025-12-01).
2. Lagatta, E. Saturn's Rings Will Disappear From View of Ground-based Telescopes in 2025. Here's Why. USA Today. Available at: https://www.usatoday.com/story/news/nation/2024/11/30/saturn-rings-disappear-2025/76498718007/ (accessed 2025-12-01).
3. NASA, Saturn Facts. NASA.gov. Available at: https://science.nasa.gov/saturn/facts/ (accessed 2025-12-01).
4. Raynor, K. Why Saturn's Rings Are Vanishing This Month, and what it means. BBC Sky at Night Magazine. Available at: https://www.skyatnightmagazine.com/space-science/saturn-ring-plane-crossing (accessed 2025-12-01).
5. NASA, Cassini. NASA.gov. Available at: https://science.nasa.gov/mission/cassini/spacecraft/cassini-orbiter/ultraviolet-imaging-spectrograph/ (accessed 2025-12-01).
6. NASA, Cassini – Composite Infrared Spectrometer. NASA.gov. Available at: https://science.nasa.gov/mission/cassini/spacecraft/cassini-orbiter/composite-infrared-spectrometer/ (accessed 2025-12-01).
7. NASA, Saturn Rings: Overview. NASA.gov. Available at: https://science.nasa.gov/mission/cassini/science/rings/ (accessed 2025-12-01).
8. Serigano, J.; Horst, S. M.; He, C.; et al. Compositional Measurements of Saturn's Upper Atmosphere and Rings From Cassini INMS: An Extended Analysis of Measurements From Cassini's Grand Finale Orbits. JGR Planets 2022, 127 (6), e2022JE007238. DOI: 10.1029/2022JE007238