As if dainty, iridescent fairies are racing around a cosmic track, Neptune’s rings sparkle in a stunning new view captured by the James Webb Space Telescope (JWST), the most powerful off-world observatory yet built. This is the sharpest image of the planet’s rings obtained since the Voyager 2 flyby in 1989, and it reveals a plethora of never-before-seen details.
“For me, looking at JWST’s new Neptune image is like catching up with a friend you haven’t seen in ten-plus years–and they look GREAT,” wrote Jane Rigby, an astrophysicist at NASA’s Goddard Space Flight Center who serves as the agency’s JWST operations project scientist, in an e-mail to Scientific American.
After a nail-biting launch on Christmas Day in 2021, the telescope began full operation this July and has since splashed the news with jaw-dropping images of nebulae and discoveries of ancient galaxies that could “break cosmology.” But JWST’s keen infrared eyes are opening new vistas closer to home as well when they are turned to our solar system’s retinue of worlds.
The telescope’s view of Neptune, for instance, shows the planet’s dust bands with unprecedented clarity. These fuzzy particles are found between the brighter, more ice-dominated rings. Mark McCaughrean is senior science adviser at European Space Agency (ESA), and a member the JWST Science Working Group.
Marcia Rieke, University of Arizona astronomer, was able to take a look at the new Neptune views. She said that she was “as usual, blown away” by what she saw. Rieke recalls years ago trying to view Neptune’s rings using a ground-based telescope located on Kitt Peak, Arizona. She says, “We saw almost nothing due to how thin and clumpy they are.” “It’s amazing to see them so clearly and easily [with the JWST ].”
Clouds of methane ice appear as bright streaks and spots in the image, gleaming in the faint sunlight that reaches Neptune from about 2.8 billion miles away. Seven of the planet’s 14 moons are also tucked into the JWST photograph. The brightest is the oddball Triton, a hefty natural satellite covered in nitrogen ice that reflects about 70 percent of the incoming sunlight. Triton orbits in the opposite direction to most other planetary moons, even those around Neptune. Researchers believe that Triton is a migrant from outer solar system, captured by Neptune’s gravity.
” It will be cool to measure the spectrum of Triton, as it represents a body from further out,” McCaughrean said.
JWST’s Infrared View also shows a thin glowing circle around the Equator. This is likely caused by warmer gas flowing towards Neptune’s midlatitudes in an ever-churning pattern global atmospheric circulation. Such features may drive the planet’s powerful winds and storms, according to an ESA press release.
” What really stands out to me is all the beautiful clouds and storms present in Neptune’s atmosphere,” says Nikole, an associate professor of Astronomy at Cornell University. “Neptune has the highest measured wind speeds in the solar system, with average wind speeds near [the] equator of 700 miles per hour and peak wind speeds in places that are more than 1,000 mph.” While Lewis’s own work with JWST will focus on planets beyond the solar system, she calls the new image “an amazing snapshot of its turbulent weather.”
Unlike Voyager 2, where you could see Neptune at a single moment in time, JWST will continue to study Neptune and other solar system denizens as long as the observatory is around. McCaughrean states that scientists will be able to compare these and future JWST images to better understand the longer-term atmospheric changes on Neptune, such as Neptune’s seasons. Because the planet is tilted at a 28-degree angle along its axis, it experiences four seasons, just like Earth. But on Neptune, each lasts about 40 years as a result of that world’s lengthy 164-Earth-year journey around the sun. McCaughrean states that the planet is about to enter a new season since Voyager 2 flew past.
While Neptune is the star of the new snapshot, McCaughrean said that the zoomed view shows “a bit of the poetic side” of the planets in space. He was referring to the background of distant stars and galaxies which seem to surround the ice giant.
At nearly a million miles away from Earth, and armed with a variety of imaging tools and instruments, JWST will continue to offer deeper and more detailed views of the universe and our place within it. McCaughrean states that JWST has already added that cosmic perspective in just a few months. “But to be truthful, you haven’t seen anything .”