picture The James Webb Space Telescope has taken the clearest picture of Neptune in more than 30 years, capturing its dust rings and seven moons.
Neptune, dubbed the most distant planet in the solar system after Pluto was demoted to a dwarf world in 2006, is more than 2.6 billion miles from Earth. The only spacecraft to visit the distant gas giant was Voyager 2 during a flyby in 1989; This probe bounced back images of bright rings around Neptune, made up of clumps of dust dropped from its nearby natural satellites.
Star Trek…Neptune capture by the JWST. Image credits: NASA, ESA, CSA, STScI. Click to enlarge or Click here for a close-up
Now, JWST – the multi-billion dollar machine whose launch was delayed by years last year – has provided astronomers with new observations of Neptune’s dust rings and moons.
“It’s been three decades since we last saw these faint, dusty rings, and this is the first time we’ve seen them in the infrared,” said Heidi Hammel, Neptune systems expert and interdisciplinary scientist for Webb, said in an opinion.
The light blue looking blob with diffraction spikes in the upper left of the snapshot above is Neptune’s largest moon, Triton, which has a strange retrograde orbit and is one of the few geologically active natural satellites in the Solar System.
There are six other moons that appear as small blurry blobs; Three of them, Galatea, Naiad, Thalassa, are on Neptune’s left side embedded in the dust rings, while Despina is on the right side. Larissa is just below Despina outside the rings and Proteus is further to the right.
Neptune is rich in heavier elements and appears blue due to small amounts of methane in its atmosphere. Comparisons of Hubble Space Telescope and James Webb Space Telescope images show what the planet looks like at different wavelengths. Visible-light observations of Neptune by Hubble show the planet’s color but miss other details, while infrared viewing reveals its dust rings.
Neptune in a new light! 🔵Hubble's view of this planet looks pretty different from @NASAWebb's new image, on the right.That's because these two telescopes looked at the planet in different wavelengths of light. ⬇️ pic.twitter.com/omelj0ZkDX
— Hubble (@NASAHubble) September 21, 2022
The dark color in the JWST images is due to methane absorbing infrared light. The planet’s bright spots and bands are due to methane ice clouds reflecting sunlight before being absorbed by the methane gas. Neptune has at least 14 moons; Outshining its host planet, Triton is the brightest, reflecting 70 percent of the sunlight that reaches its surface.
However, all is not well
However, NASA experts are concerned about a developing problem and have temporarily halted some mid-infrared observations while one of their instruments undergoes a technical review.
“The James Webb Space Telescope’s Mid-Infrared Instrument (MIRI) has four observation modes‘, ‘Nasa explained in an opinion. “On August 24, a mechanism supporting one of these modes, known as medium-resolution spectroscopy (MRS), showed what appeared to be increased friction during setup for a scientific observation.
“This mechanism is a lattice wheel that allows scientists to choose between short, medium and longer wavelengths when observing in MRS mode – the best way forward.”
Only the center wavelength of MIRI’s observing modes is affected; The other modes that support imaging, low-resolution spectroscopy, and coronagraphy still work. ®
https://www.theregister.com/2022/09/22/jwst_neptune_images_faults/ The James Webb Space Telescope takes a picture of Neptune’s rings • The Register