The James Webb Space Telescope takes a picture of Neptune’s rings • The Register

Pic The James Webb Space Telescope has taken the sharpest image of Neptune, capturing its dust rings and seven moons, in more than 30 years.

Neptune, designated the farthest planet in the Solar System after Pluto was demoted to a dwarf world in 2006, is more than 2.6 billion miles away from Earth. The only spacecraft to visit the distant gas giant was Voyager 2 during an overflight in 1989; that spacecraft returned images of bright rings around Neptune made up of piles of dust released by its nearby natural satellites.

Star trek … Capture of Neptune by the JWST. Image credit: NASA, ESA, CSA, STScI. Click to enlarge or click here for a close-up

Now, the JWST – the multi-billion dollar machine that was delayed for years before launching 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 infrared,” said Heidi Hammel, Neptune system expert and interdisciplinary scientist for Webb, in a statement. .

The bright blue dot with diffraction tips on the top left of the snap 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 fuzzy spots; three of them, Galatea, Naiad, Thalassa, are on the left side of Neptune embedded in the dust rings, while Despina is on the right. Larissa is directly below Despina outside the rings and Proteus is further to the right.

Neptune is rich in heavier elements and appears blue due to the small amounts of methane in its atmosphere. Comparing images from the Hubble Space Telescope and the James Webb Space Telescope shows what the planet looks like at different wavelengths. Observations of Neptune in Hubble’s visible light show the planet’s color but other details are missing, while observing it in infrared reveals its dust rings.

The dark color in the JWST images is due to infrared light absorbing methane. The bright spots and bands across the planet are due to methane ice clouds reflecting sunlight before being absorbed by the methane gas. Neptune has at least 14 moons; Triton eclipses its host planet and is the brightest as it reflects 70% of the sunlight that reaches its surface.

It’s not all right, though

But NASA technicians are concerned about a developing problem and have temporarily suspended some observations in mid-infrared light while one of its instruments is undergoing a technical examination.

“The James Webb Space Telescope’s Mid-Infrared Instrument (MIRI) has four modes of observation,” NASA said in a statement. “On August 24, a mechanism that supports one of these modalities, known as medium resolution spectroscopy (MRS), showed what appears to be increased friction when setting up for scientific observation.

“This mechanism is a grating that allows scientists to select between short, medium and longer wavelengths when making observations using the MRS mode. After preliminary health checks and investigations into the problem, a review committee of the anomalies on 6 September to evaluate the best path forward “.

Only the average wavelength of the MIRI observation modes is affected; other modalities that support imaging, low-resolution spectroscopy, and coronary artery still work. ®