Neptune’s Ghostly Rings and Aura Revealed

When you think of planets with rings, Saturn normally takes the cake for its iconic icy spirals. But Saturn isn’t the only planet in our solar system that the universe has put a ring around. In fact, the James Webb Space Telescope (JWST) just captured the brightest image of Neptune’s rings in more than 30 years.

“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,” Heidi Hammel, a Neptune systems expert and interdisciplinary scientist for Webb, said in a statement. a press release. .

In 1989, NASA’s Voyager 2 became the first spacecraft to observe Neptune during its flyby in the late 1980s. Now JWST has captured this sharp image of the planet’s rings, some of which have not been detected since that mission for more than three decades. past. The photo clearly shows finer dust bands of Neptune, in addition to the bright and narrow rings.

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Neptune is an ice giant because of the chemical makeup of the planet’s interior. Compared to the gas giants of the solar system (Jupiter and the more famous ring of Saturn), Neptune is much richer in elements heavier than hydrogen and helium.

JWST saw seven of Neptune’s 14 known moons. Triton dominates this Webb portrait of Neptune as a very bright point of light with the distinctive diffraction peaks seen in many of Webb’s images. CREDIT: NASA, ESA, CSA, STScI.

JWST’s Near-Infrared Camera (NIRCam) can see space objects in a different light spectrum, the near-infrared range. This means that Neptune does not appear blue in the pictures taken by the NIRCam. “The planet’s methane gas absorbs red and infrared light so strongly that the planet is quite dark at these near-infrared wavelengths, except where high-altitude clouds are present,” NASA said. These methane ice clouds appear as bright streaks and spots, reflecting sunlight before being absorbed by the methane gas. The Hubble Space Telescope and the WM Keck Observatory also captured these rapidly changing cloud features.

Astronomers suspect the thin line of brightness around the planet’s equator could be a sign of atmospheric circulation fueling Neptune’s winds and storms. It glows more at infrared wavelengths than the surrounding cooler gases because the atmosphere sinks and warms at Neptune’s equator.

Neptune takes 164 Earth years to orbit the sun, so the North Pole is just out of astronomers’ view. However, the JWST images show a possible brightness above that. JWST can see a previously known vortex at Neptune’s south pole, but a continuous band of high-latitude clouds surrounding it was first revealed in these images.

[Related: Neptune is already an ice giant, but it might be having a cold snap.]

JWST also captured images of seven of Neptune’s 14 known moons (Gatea, Naiad, Thalassa, Despina, Proteus, Larissa, and Triton). Neptune’s large and “unusual” moon Triton dominates this portrait of the planet, creating a point with diffraction peaks that make it resemble a star. Triton is covered in a frozen gloss of condensed nitrogen and reflects 70 percent of the sunlight that hits it. It is much brighter than Neptune in this image because the planet’s atmosphere darkens due to methane absorption at these near-infrared wavelengths. Since Triton orbits Neptune in an unusual retrograde (sometimes called backwards), astronomers believe this moon was originally a Kuiper Belt object that Neptune used its gravity to record. Studies of both Triton and Neptune are planned by JWST in the coming year.

Since Neptune’s first documented discovery in 1846, Neptune has long fascinated scientists. Compared to Earth, it is 30 times farther from the sun. It revolves around the remote, dark region of the outer solar system, where the sun is so small and dim that noon on Neptune is comparable to a twilight twilight on Earth.