Humanity sees Neptune’s rings in a whole new light thanks to the James Webb Space Telescope.
In an infrared image released Sept. 21, Neptune and her dust tiaras take on an ethereal glow on space ink background. The stunning portrait is a huge improvement on the previous close-up of the rings, which was taken over 30 years ago.
Unlike the dazzling belts surrounding Saturn, Neptune’s rings appear dark and dim in visible light, making them difficult to see from Earth. The last time anyone saw the rings of Neptune was in 1989, when NASA’s Voyager 2 spacecraftafter crossing the planet, took some grainy photos from about 1 million miles away (SN: 07/08/17). In these photos, taken in visible light, the rings appear as thin concentric arcs.
As Voyager 2 continued into interplanetary space, Neptune’s rings hid again – until July. It is then that the James Webb Space Telescopeor JWST, turned its sharp infrared gaze to the planet about 4.4 billion kilometers away (SN: 7/11/22).
Neptune itself appears mostly dark in the new image. That’s because methane gas in the planet’s atmosphere absorbs much of its infrared light. A few bright patches mark where high-altitude methane ice clouds reflect sunlight.
And then there are the ever-elusive rings. “The rings contain a lot of ice and dust, which are extremely reflective of infrared light,” says Stefanie Milam, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and one of the JWST project scientists. The enormity of the telescope’s mirror also makes its images very sharp. “JWST was designed to observe the first stars and galaxies across the universe, so we could really see fine detail that we hadn’t been able to see before,” says Milam.
The next JWST observations will examine Neptune with other scientific instruments. This should provide new insights into the composition and dynamics of the rings, as well as the evolution of Neptune’s clouds and storms, Milam says. “There’s more to come.”