James Webb telescope reveals Neptune’s rings – Infrared image shows Neptune’s faint rings and seven of its moons

James Webb telescope reveals Neptune’s rings – Infrared image shows Neptune’s faint rings and seven of its moons
James Webb telescope reveals Neptune’s rings – Infrared image shows Neptune’s faint rings and seven of its moons

Fascinating sight: A new image from the James Web Space Telescope reveals the thin rings of the planet Neptune. Its wafer-thin ring system is almost impossible to see from Earth. Only NASA’s Voyager spacecraft showed the shape and structure of Neptune’s bluish, dusty rings. The Webb telescope’s near-infrared camera gives us the first clear image of these rings in 30 years, capturing seven of Neptune’s 14 known moons.

Neptune is the outermost planet in our solar system and one of the most mysterious. Because of its great distance from Earth, the features of this icy planet are difficult to discern, even with powerful telescopes. It has not received a close visit since the Voyager-2 spacecraft flew by in 1989. It is all the more astonishing what the sparse data and recordings about the magnetic field, storms and inner workings of this ice planet suggest.

Dirty gray instead of blue

NASA’s new James Web Telescope has now set its sights on the icy planet Neptune. From its vantage point at Lagrange Point 2, 1.5 million kilometers away, the telescope’s Near-Infrared Camera (NIRCam) captured the planet in the wavelength range of 0.6 to 5 micrometers – in the red and near-infrared part of light.

Unlike in visible light, Neptune does not appear blue in this image. This is because the typical blue hue of the two ice giants, Uranus and Neptune, is created by the relatively high proportion of methane in their gas envelope. In the red and near-infrared wavelength range, however, this gas absorbs almost all radiation, so the planet appears relatively colorless and dark. Only the high clouds of methane ice shine brightly, reflecting the sunlight strongly and therefore appearing as whitish patches.

First sight of the rings in infrared

Even more exciting is the sight of Neptune’s rings, which are clearly visible in this image for the first time since Voyager-2 passed. “It’s been three decades since we last saw these faint, dusty ribbons — and this is the first time we’ve seen them in infrared,” says Webb team member Heidi Hammel. The rings around Neptune’s equator appear slightly tilted because the ice planet is currently turning the southern hemisphere more towards us on its 164-year orbit around the sun.

The image shows seven of Neptune’s 14 moons. © NASA/ESA/CSA, Joseph DePasquale (STScI)

A faint, thin line can be seen in Neptune’s atmosphere just at the equator, with a not quite closed band of bright clouds to the south. The planetary researchers of the Webb team suspect that this could be a visual signature of the extremely rapidly rotating atmosphere around the planet. With wind speeds of up to 2,100 kilometers per hour, Neptune is the planet with the fastest winds in the solar system.

Triton and six of his companions

Also visible in this image are seven of Neptune’s 14 known moons. Dominating the top of the image is Neptune’s largest moon, Triton, with a diameter of around 2,700 kilometers. Its ice-covered surface also reflects the sunlight strongly in the near infrared. It far outshines Neptune and produces a radiating halo of latticed scattered light on camera.

Six other, much smaller moons can be seen close to Neptune, some lying inside and some outside the arcs of the rings. Among them are Naiad and Thalassa. Unlike Triton, these two satellites do not follow a straight, circular path around their planet, but perform an unusual dance. Naiad appears to meander around its neighbor, as revealed in 2019 Hubble Space Telescope images.

Source: Space Telescope Science Institute

September 22, 2022

– Nadia Podbregar

The article is in German

Tags: James Webb telescope reveals Neptunes rings Infrared image shows Neptunes faint rings moons

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