#moons

This image of Uranus from NIRCam (Near-Infrared Camera) on NASA's James Webb Space Telescope shows the planet and its rings in new clarity. The planet's seasonal north polar cap gleams in a bright white, and Webb's exquisite sensitivity resolves Uranus' dim inner and outer rings, including the Zeta ring—the extremely faint and diffuse ring closest to the planet. This Webb image also shows 14 of the planet's 27 moons: Oberon, Titania, Umbriel, Juliet, Perdita, Rosalind, Puck, Belinda, Desdemona, Cressida, Ariel, Miranda, Bianca, and Portia. One day on Uranus is about 17 hours, so the planet's rotation is relatively quick. This makes it supremely difficult for observatories with a sharp eye like Webb to capture one simple image of the entire planet – storms and other atmospheric features, and the planet's moons, move visibly within minutes. This image combines several longer and shorter exposures of this dynamic system to correct for those slight changes throughout the observing time. Webb's extreme sensitivity also picks up a smattering of background galaxies—most appear as orange smudges, and there are two larger, fuzzy white galaxies to the right of the planet in this field of view.

Image Credit: NASA, ESA, CSA, 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. 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 garner important clues about the flow of material in the current Saturn system, as well as its past history.

Image Credit: NASA, ESA, CSA, Matthew Tiscareno (SETI Institute), Matthew Hedman (University of Idaho), Maryame El Moutamid (Cornell University), Mark Showalter (SETI Institute), Leigh Fletcher (University of Leicester), Heidi Hammel (AURA)

This image of the Neptune system, captured by Webb’s Near-Infrared Camera (NIRCam), reveals stunning views of the planet’s rings, which have not been seen with this clarity in more than three decades. Webb’s new image of Neptune also captures details of the planet’s turbulent, windy atmosphere. Neptune, an ice giant, has an interior that is much richer in elements heavier than hydrogen and helium, like methane, than the gas giants Jupiter and Saturn. Methane appears blue in visible wavelengths but, as evident in Webb’s image, that’s not the case in the near-infrared. Methane so strongly absorbs red and infrared light that the planet is quite dark at near-infrared wavelengths, except where high-altitude clouds are present. These methane-ice clouds are prominent in Webb’s image as bright streaks and spots, which reflect sunlight before it is absorbed by methane gas. To the upper left of the planet in this image, one of Neptune’s moons, Triton, also sports Webb’s distinctive eight diffraction spikes, an artifact of the telescope’s structure. Webb also captured 6 more of Neptune’s 14 known moons, along with a smattering of distant galaxies that appear as dim splotches and a nearby star. NIRCam was built by a team at the University of Arizona and Lockheed Martin’s Advanced Technology Center.

Image Credit: NASA, ESA, CSA, STScI