18/12/2023
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The NASA/ESA/CSA James Webb Space Telescope recently trained its sights on the strange and enigmatic Uranus, an ice giant orbiting on its side. Webb discovered a dynamic world with rings, moons, storms and other atmospheric features – including a seasonal polar cap. The image expands on the two-color version released earlier this year, adding additional wavelength coverage for a more detailed look.
With its exquisite sensitivity, Webb captured the faint inner and outer rings of Uranus, including the elusive Zeta ring—the faintest and most diffuse ring closest to the planet. It also photographed many of the planet’s 27 known moons, even seeing some smaller moons inside the rings.
At visible wavelengths, Uranus appeared as a quiet, solid blue ball. At infrared wavelengths (as seen here), Webb reveals a strange and dynamic ice world filled with amazing atmospheric features.
One of the most notable of these is the planet’s seasonal north polar cap. Compared to the image taken earlier this year, it’s easier to see some of the cap’s details in these new images. These include a bright, white, inner cap and a dark track at the base of the polar cap, toward lower latitudes.
Many bright storms can also be seen near and below the southern boundary of the polar cap. The number of these storms and how often and where they appear in Uranus’ atmosphere is likely due to a combination of seasonal and meteorological effects.
As the planet’s pole begins to move toward the Sun, the polar cap becomes more prominent as it approaches the solstice and receives more sunlight. Uranus reaches its next solstice in 2028, and astronomers are eager to see any possible changes in the structure of these features. Webb will help dissect the seasonal and meteorological effects that influence Uranus’ storms, helping astronomers understand the planet’s complex atmosphere.
Because Uranus orbits at a tilt of about 98 degrees on its side, 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 winter.
With Webb’s unparalleled infrared resolution and sensitivity, astronomers can now see Uranus and its unique features with stunning clarity. These details will be invaluable for planning future missions to Uranus, especially the proposed Uranus orbiter and probe, especially the close Zeta ring.
Scientists want to bring any visiting spacecraft close enough to the planet to measure Uranus’ gravity and better analyze the atmosphere. However, such a close approach must be carefully planned to avoid collisions with possible debris from the icy and dusty rings.
Uranus can also serve as a proxy for studying the many distant, similar-sized exoplanets that have been discovered in the past few decades. This ‘exoplanet within exoplanet’ will help astronomers understand how planets of this size work, what their weather is like, and how they formed. It helps us understand our own solar system as a whole by putting it in a larger context.
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Webb is the largest, most powerful telescope ever launched into space. Under an international cooperation agreement, ESA provided the telescope’s launch service using the Ariane 5 launch vehicle. Working with partners, ESA was responsible for the development and qualification of Ariane 5 adaptations for the Webb mission and procurement of the launch service through Arianespace. ESA provided 50% of MIRI’s workhorse spectrograph and 50% of MIRI’s workhorse spectrograph, which was designed and built by a consortium of nationally funded European institutions (The MIRI European Consortium) in collaboration with JBL and the University of Arizona.
Webb is an international partnership between NASA, ESA and the Canadian Space Agency (CSA).
Contact:
ESA Media Relations
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