With his first picture of Neptune, NASA’s James Webb Space Telescope shows its capabilities on a much more familiar scale. Webb’s cameras are shedding new light on the gas giant, and they’ve also captured the sharpest glimpse of the planet’s rings in more than 30 years.
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Hey Neptune. Did you call?
Webb’s latest image is the clearest look at Neptune’s rings in more than 30 years, and the first time we see them in infrared light. Enjoy Webb’s haunting, ethereal view of the planet and its dust bands, rings and moons: https://t.co/Jd09henF1F #IAC2022 pic.twitter.com/17QNXj23ow— NASA Webb Telescope (@NASAWebb) September 21, 2022
Webb’s latest image is startling because it clearly shows the planet’s rings, some of which haven’t been seen since NASA’s Voyager 2 first flew close to Neptune in 1989. Neptune’s fainter dust bands are also visible in the Webb image, along with many brilliant, thin rings.
“It’s been three decades since we last saw these faint, dusty rings, and this is the first time we’ve seen them in infrared,” said Heidi Hammel, a Neptune systems expert and interdisciplinary scientist for Webb. These very faint rings can be observed so close to Neptune because of Webb’s exceptionally consistent and accurate image quality.
Scientists have been fascinated by Neptune since its discovery in 1846. Neptune orbits in the distant, dark region of the outer solar system, at a distance of 30 times that of Earth from the sun. Because of the sun’s small size and low luminosity at such a great distance, midday on Neptune is roughly equivalent to early morning hours on Earth.
In terms of its chemical composition, this planet is classified as an ice giant. Neptune, unlike Jupiter and Saturn, has a relatively large amount of elements other than hydrogen and helium. Images of Neptune taken by the Hubble Space Telescope at visible wavelengths show that the planet has its characteristic blue color due to trace concentrations of gaseous methane.
Since the near-infrared range of Webb’s Near-Infrared Camera (NIRCam) is between 0.6 and 5 microns, Neptune does not appear blue to Webb. In reality, the planet is quite black at these near-infrared wavelengths, especially in regions where there are high-altitude clouds, because the methane gas absorbs this light so powerfully. Clouds made up of methane ice are easily recognizable as brilliant streaks and spots because they reflect sunlight before the gas absorbs it. These rapidly changing cloud structures have been recorded over the years by the Hubble Space Telescope and the WM Keck Observatory, among others.
Seven of Neptune’s fourteen moons were also photographed by Webb. In this painting of Neptune by Webb, the brightest feature is not a star, but rather Webb’s signature diffraction peaks, which can be seen in many of his photographs. This really is Triton, Neptune’s massive and peculiar moon.