As if cute fairies and iridescents were racing around a cosmic path, the rings of Neptune sparkle in a stunning new scene captured by the James Webb Space Telescope (JWST), the most powerful extraterrestrial observatory yet built. This is the sharpest image of the planet’s rings obtained since the flyby of Voyager 2 in 1989, and it reveals a slew of never-before-seen details.
Jane Rigby, an astrophysicist at NASA’s Goddard Space Flight Center, who serves as the JWST Operations Project Scientist, says in an email.
After an impressive launch on Christmas Day in 2021, the telescope went into full operation in July and has since been spreading the news with stunning images of nebulae and discoveries of ancient galaxies that could “shatter cosmology.” But JWST’s infrared eyes open up new horizons closer to home, too, as they turn into our solar system’s fringe of worlds.
For example, the telescope’s view of Neptune shows the planet’s weak dust bands with unprecedented clarity. These particles appear as hazy particles between the brighter ice-dominated rings, says Mark McGreen, ESA’s senior scientific advisor and member of the JWST science working group.
When University of Arizona astronomer Marcia Ricci had the opportunity to look at the new views of Neptune, she said, “As usual, I was amazed by what we see.” Ricky, currently principal investigator for JWST’s Principal Photographer, called the Near Infrared Camera (NIRCam), recalls trying to view Neptune’s rings years ago using a ground-based telescope atop Kate in Arizona. “We basically didn’t see anything because of how thin and lumpy the rings were,” she says. “It’s great to see them so clearly and easily [with JWST]. “
Clouds of methane ice appear as bright streaks and patches in the image, shimmering in the dim sunlight hitting Neptune from about 2.8 billion miles away. Seven of the planet’s 14 moons are also tucked into the JWST image. The brightest is the eccentric Triton, a massive natural satellite covered in nitrogen ice that reflects about 70 percent of incoming sunlight. While most planets’ moons, including all the others around Neptune, rotate with the rotation of their planetary host, Triton does so in the opposite direction. This orbit suggests to the researchers that the object may have been a migrant from the outer solar system that was captured long ago by Neptune’s gravity.
“It would be really cool to go and measure the spectrograph of Triton because it’s an object that came from far away,” McGreen says.
JWST’s infrared view also shows a thin glowing band surrounding the equator, likely caused by a flow of warmer gas toward Neptune’s mid-latitudes as part of a perpetually wavy pattern of global atmospheric circulation. According to an ESA press release, such features could drive strong winds and storms on the planet.
“What’s really showing me are all the wonderful clouds and storms that are in Neptune’s atmosphere,” says Nicole Lewis, assistant professor of astronomy at Cornell University. Neptune has the highest measured wind speeds in the Solar System, with average wind speeds approaching [the] The equator is 700 mph and peak wind speeds are in places over 1,000 mph.” While Lewis’ work with JWST will focus on planets outside the solar system, she calls the new image “a stunning shot of their turbulent weather.”
Unlike Voyager 2, which provided snapshots of Neptune from a single moment in time, JWST’s studies of Neptune and other residents of the solar system will continue for as long as the observatory itself. By comparing these and future JWST images with those from Voyager 2, scientists hope to learn more about long-term atmospheric changes on the planet, such as the seasons of Neptune, McGreen says. Since the planet is tilted at an angle of 28 degrees to its axis, it goes through four seasons, just like the Earth. But on Neptune, each lasts about 40 years as a result of the world’s long 164-year journey around the sun. McCurren says that means the planet has just entered a different season than when Voyager 2 flew by.
While Neptune may be the crown jewel in the newly released shot, the miniature view shows “a little bit of the poetic side of planets suspended in space,” says McGreen, pointing to the backdrop of distant stars and galaxies that seem to surround the ice giant.
Nearly a million miles from Earth and filled with imaging tools, JWST will continue to provide a deeper, clearer view of the universe and our place in it. “The JWST, even in just a couple of months, has started adding this cosmic perspective,” McGreen says. “But to be honest, you haven’t seen anything yet.”