Webb has returned an image of ringed Uranus, currently experiencing the dog days of northern hemisphere summer.

The planet Uranus on a black background. The planet appears light blue with a large, white patch on the right side. The image is labelled to indicate the locations of the planet’s clouds, polar cap, and zeta ring
This annotated, zoomed-in image of Uranus, captured by Webb’s Near-Infrared Camera (NIRCam) on 6 February 2023, reveals stunning views of the planet’s rings, as well as clouds and the polar cap.
NASA / ESA / CSA / STScI / J. DePasquale (STScI)

The James Webb Space Telescope is continuing its portfolio of the outer solar system, this time returning an image of ringed Uranus. The tipped-over ice giant is currently facing its northern pole straight toward the Sun. Imaged previously by Voyager 2 (from a distance of only 50,640 miles, or 81,500 km) and by the adaptive-optics system on the Keck Observatory in Hawai'i, the planet revealed new details to Webb's sensitive instruments over an exposure time of just 12 minutes.

The image shown here is taken at two infrared wavelengths centered on 1.4 and 3.0 microns. The infrared colors have been translated to blue and orange, respectively, to create an image we can see. Infrared light reveals the bright polar cap, which appears during Uranian spring and disappears in the autumn. The image shows that the polar cap has gradations, appearing brightest at its center. There are also two white clouds, probably associated with storms, and 11 of the planet's 13 dusty rings can be seen.

One year on Uranus is equivalent to 84 on Earth, so light touches the northern hemisphere for 42 years. Then, since the planet spins on its side, the north cap will face cold, dark space for another 42 years. The difference between the two hemispheres results in extreme weather, with measured wind speeds of up to 560 miles per hour. In some places, this planet is even colder than farther-out Neptune, although why that is remains a mystery.

The planet Uranus is on a black background just left of centre. It is coloured light blue and displays a large, white patch on the right side as well as two bright spots and a surrounding system of nested rings oriented vertically
This wider view of the Uranian system with Webb’s NIRCam instrument features the planet Uranus as well as six of its 27 known moons (most of which are too small and faint to be seen in this short exposure). A handful of background objects, including many galaxies, are also seen.
NASA / ESA / CSA / STScI / J. DePasquale (STScI)

This image is the latest to join Webb's planetary pantheon, which also includes Mars, Jupiter, and Neptune. But while these images are beautiful in themselves, the science is only beginning. Stay tuned for more as astronomers find insights into this icy world.




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April 7, 2023 at 4:56 pm

I am wondering if the "dog days" of Uranus referred to in the article are indeed a time that the "dog star" (Sirius as I understand it) would be more "visible" from Uranus than at other times of during the Uranus "year".

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April 7, 2023 at 8:54 pm

I'm sorry, but your paragraph starting "One year on Uranus is equivalent to 84 on Earth" doesn't describe the seasons on Uranus because it completely dismisses Spring and Fall. Summer and Winter do not last 42 years.
I checked the JWST page for this image and it says that "Currently, it is late spring for the northern pole". It also says that "Uranus’ northern summer will be in 2028". And it says that the polar cap seems to "vanish in the fall".
Each season should last about 21 years, but since the orbit of Uranus has an eccentricity of 5%, they will not be equal in length.

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Monica Young

April 8, 2023 at 3:05 pm

Thanks for the note! I've fixed the imprecise language.

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April 10, 2023 at 8:19 am

🙂 I can't fix my language or tone. 🙁

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