BREAKING: Webb makes first stunning observation of Saturn’s rings, which shine brightly

Image of Saturn and some of its moons, taken by the James Webb Space Telescope’s NIRCam instrument on June 25, 2023. In this monochrome image, the NIRCam filter F323N (3.23 micron) is color mapped in an orange hue.Credits: NASA, ESA, CSA, STScI, M. Tiscareno (SETI Institute), M. Hedman (University of Idaho), M. El Moutamid (Cornell University), M. Showalter (SETI Institute), Image processing by L. Fletcher (University of Idaho, Leicester), H. Hammel (AURA); J. DePasquale (STScI)

On June 25, 2023, NASA’s James Webb Space Telescope turned to famed ringed world Saturn for its first near-infrared observations of the planet. The initial imagery from Webb’s NIRCam (Near-Infrared Camera) is already fascinating researchers.

Saturn itself appears extremely dark at this infrared wavelength observed by the telescope, as methane gas absorbs almost all of the sunlight falling on the atmosphere. However, the icy rings stay relatively bright, leading to the unusual appearance of Saturn in the Webb image.

Saturn (Webb NIRCam Annotated)

Image of Saturn and some of its moons, captured by the James Webb Space Telescope’s NIRCam instrument on June 25, 2023. In this monochrome image, NIRCam filter F323N (3.23 microns) was color mapped with an orange hue. Credit: NASA, ESA, CSA, STScI, M. Tiscareno (SETI Institute), M. Hedman (University of Idaho), M. El Moutamid (Cornell University), M. Showalter (SETI Institute), L. Fletcher (University of Leicester), H. Hammel (AURA); image processing by J. DePasquale (STScI)

This image was taken as part of Webb Guaranteed Time Observation program 1247. The program included several very deep exposures of Saturn, which were designed to test the telescope’s capacity to detect faint moons around the planet and its bright rings. Any newly discovered moons could help scientists put together a more complete picture of the current system of Saturn, as well as its past.

Saturn, the sixth planet from the sun in our solar system, is known for its distinctive and striking ring system. This gas giant is the second-largest planet in the solar system after

Saturn has a fascinating system of over 80 moons, the most famous of which is Titan, larger than the planet Mercury and enveloped in a dense, nitrogen-rich atmosphere. The planet is also renowned for its beautiful but short-lived hexagonal storm at its north pole. The gas giant’s weather patterns include high-velocity winds, which can reach up to 1,800 kilometers per hour, and giant storms that periodically appear on its surface. Saturn’s yellowish hue is a result of ammonia crystals in its upper atmosphere. Its average distance from the sun is about 1.4 billion kilometers, and a single orbit takes approximately 29.5 Earth years.

When comparing the northern and southern poles of the planet in this image, the differences in appearance are typical with known seasonal changes on Saturn. For example, Saturn is currently experiencing northern summertime, with the southern hemisphere emerging from the darkness at the end of a winter. However, the northern pole is particularly dark, perhaps due to an unknown seasonal process affecting polar aerosols in particular. A tiny hint of brightening towards the edge of Saturn’s disk might be due to high-altitude methane fluorescence (the process of emitting light after absorbing light), emission from the trihydrogen ion (H3+) in the ionosphere, or both; spectroscopy from Webb could help confirm this.

Missions like NASA’s Pioneer 11, Voyagers 1 and 2, the

  • Heidi B. Hammel is a Webb interdisciplinary scientist leading Webb’s Cycle 1 Guaranteed Time Observations (GTO) of the solar system. She is the vice president for science at the Association of Universities for Research in Astronomy (AURA) in Washington, D.C.
  • Leigh Fletcher is a professor of planetary science at the University of Leicester in England. Leigh is the principal investigator for several of Webb’s Guaranteed Time Observation Programs, including Program 1247 highlighted here.
  • Matt Tiscareno is a Senior Research Scientist at the SETI Institute, California, where he studies the dynamics of planetary systems, including planetary rings. He is an integral member of the Webb Guaranteed Time Observation team for the study of Saturn.
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