This image of Uranus from NIRCam on NASA's James Webb Space Telescope exquisitely captures Uranus's seasonal north polar cap and dim inner and outer rings. This Webb image also shows 9 of the planet's 27 moons—clockwise starting at 2 o'clock, they are: Rosalind, Puck, Belinda, Desdemona, Cressida, Bianca, Portia, Juliet, and Perdita. Credit: NASA, ESA, CSA, STScI
Key points:
- The James Webb Space Telescope has captured a more detailed photo of Uranus compared with previous attempts.
- The telescope imaged the planet’s elusive Zeta ring, as well as many of it’s 27 known moons.
- The detailed image sheds light on Uranus’ seasonal north polar cloud cap, which could help astronomers understand the planet's complex atmosphere.
Turning its sights to Uranus, the James Webb Space Telescope recently captured a photo of the ice giant with all its dynamic features—rings, moons, storms, and other atmospheric features, including a seasonal polar cap. The image expands upon a two-color version released earlier this year, adding additional wavelength coverage for a more detailed look.
With its exquisite sensitivity, Webb captured the dim inner and outer rings of Uranus, including the elusive Zeta ring—the extremely faint and diffuse ring closest to the planet. It also imaged many of the planet's 27 known moons, even seeing some small moons within the rings.
Webb was able to capture a much better view of Uranus’ seasonal north polar cloud cap compared with previous images. Details show the bright, white, inner cap and the dark lane in the bottom of the polar cap, toward the lower latitudes. Several bright storms can also be seen near and below the southern border of the polar cap. The number of these storms, and how frequently and where they appear in Uranus's atmosphere, might be due to a combination of seasonal and meteorological effects.
The polar cap appears to become more prominent when the planet's pole begins to point toward the sun, as it approaches solstice and receives more sunlight. Uranus reaches its next solstice in 2028, and astronomers are eager to watch any possible changes in the structure of these features. Webb will help disentangle the seasonal and meteorological effects that influence Uranus's storms, which is critical to help astronomers understand the planet's complex atmosphere.
Because Uranus spins on its side at a tilt of about 98 degrees, it has the most extreme seasons in the solar system. For nearly a quarter of each Uranian year, the sun shines over one pole, plunging the other half of the planet into a dark, 21-year-long winter.
Uranus can also serve as a proxy for studying the nearly 2,000 similarly sized exoplanets that have been discovered in the last few decades. This "exoplanet in our backyard" can help astronomers understand how planets of this size work, what their meteorology is like, and how they formed. This can in turn help us understand our own solar system as a whole by placing it in a larger context.