This story originally appeared on popular science.
When you think of planets with rings, Saturn usually takes the cake for its iconic ice spirals. But Saturn is not the only planet in our solar system on which the universe has placed a ring. In fact, the James Webb Space Telescope (JWST) just captured the clearest view of Neptune’s rings in over 30 years.
A new look at Neptune’s 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 the infrared,” said Heidi Hammel, Neptune systems expert and interdisciplinary scientist for Webb, in a press release.
In 1989, NASA’s Voyager 2 was the first spacecraft to observe Neptune during its flyby in the late 1980s. Now, JWST has captured this razor-sharp image of the planet’s rings – some of which haven’t been spotted since that mission over three decades ago. The photo clearly shows Neptune’s finer dust bands in addition to the bright and narrow rings.
Neptune is an ice giant due to the chemical composition of the planet’s interior. Compared to the gas giants of the Solar System (Jupiter and the more famously ringed Saturn), Neptune is much richer in elements heavier than hydrogen and helium.
where is the blue
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JWST’s near-infrared camera (NIRCam) can see space objects in a different spectrum of light called the near-infrared. This means that Neptune does not appear blue in the images captured 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 clouds are present at high altitudes,” NASA said. These methane ice clouds show up as bright streaks and patches that reflect sunlight before it’s absorbed by the methane gas. The Hubble Space Telescope and WM-Keck Observatory have also recorded these rapidly changing cloud features.
Astronomers suspect that the thin line of brightness circling the planet’s equator could be a sign that there is atmospheric circulation driving Neptune’s winds and storms. It glows more brightly at infrared wavelengths than the surrounding cooler gases because the atmosphere at Neptune’s equator is dropping and warming.
Neptune takes 164 Earth years to orbit the Sun, so its north pole is just not visible to astronomers. However, the JWST images show a possible brightness up there. JWST can see a previously known vortex at Neptune’s south pole, but in these images a continuous band of high-latitude clouds around it became visible for the first time.
The 14 moons of Neptune
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JWST also captured images of seven of Neptune’s 14 known moons (Galatea, Naiad, Thalassa, Despina, Proteus, Larissa, and Triton). Neptune’s large and ‘unusual’ moon, Triton, dominates this portrait of the planet, creating a dot with diffraction spikes that make it appear like a star. Covered in a frozen sheen of condensed nitrogen, Triton reflects 70 percent of incoming sunlight. It is much brighter than Neptune in this image because the planet’s atmosphere is obscured by methane absorption when seen at these near-infrared wavelengths. Because Triton orbits Neptune in an unusual retrograde orbit (also known as backward), astronomers believe this moon may originally have been a Kuiper Belt object that Neptune used its gravity to capture. Studies of Triton and Neptune by JWST are planned for the coming year.
Since the first documented discovery of Neptune in 1846, Neptune has long fascinated scientists. Compared to Earth, it is 30 times farther from the Sun. It orbits the remote, dark region of the outer Solar System, where the Sun is so small and faint that high noon on Neptune resembles a dim twilight on Earth.
