Neptune Shows Off Its Rings

On September 21, 2022, the James Webb Space Telescope delivered the clearest and most detailed view of Neptune’s rings in more than 30 years. Webb’s Near-Infrared Camera (NIRCam) captured several bright, narrow rings as well as the planet’s fainter dust bands. Voyager 2 was the last to detect some of these rings during its flyby in 1989, but this is the first time we have an infrared image of them.

James Webb's Neptune
Image Credit: NASA, ESA, CSA, STScI

Near-Infrared Camera in JWST
Photo credit: NASA

Since NIRCam images objects in the near-infrared range from 0.6 to 5 microns, Neptune does not appear blue to Webb because it was captured in NIRCam with infrared range light.  In fact, the methane gas so strongly absorbs red and infrared light that the planet is quite dark at these near-infrared wavelengths, except where high-altitude clouds are present. Those methane-ice clouds are prominent as bright streaks and spots, which reflect sunlight before it is absorbed by methane gas.

Before the James Webb Space Telescope capture the planet Neptune, NASA's Voyager 2 captured images of Neptune. In the summer of 1989, NASA’s Voyager 2 became the first spacecraft to observe the planet Neptune, its final planetary target. Passing about 4,950 kilometers above Neptune’s north pole, Voyager 2 made its closest approach to any planet since leaving Earth 12 years ago. Five hours later, Voyager 2 passed about 40,000 kilometers (25,000 miles) from Neptune’s largest moon, Triton, the last solid body the spacecraft will have an opportunity to study. Voyager did not capture Neptune in the infrared range. So, it looks in blue color. 

Images Voyager Took of Neptune

More about NIRCam: 

https://khjspacetelescopes.blogspot.com/2022/10/jwst-near-infrared-camera-nircam.html