The James Webb Space Telescope (JWST) has captured spectacular new infrared images of the planet Uranus revealing new details of the ice giant’s atmosphere over the north polar region, its ring system, and multiple moons.
Robotic space probes have radically altered our perceptions of the outer solar system over the past half century. Not only have they sent back vast collections of data, they have also provided us with stunning images of planets that previously were little more than blurs on photographic plates.
Unfortunately, the technology of these probes was primitive by today’s standards and some planets were only seen during brief flybys, providing us with what are essentially snapshots. A case in point is the seventh planet, Uranus, which has only been visited once in a flyby of the Voyager 2 probe as it headed out of the solar system.
Voyager’s visit revealed many secrets, not the least of which were the composition of the upper atmosphere and the first photographic evidence of the existence of Uranus’s rings. It also sent back the first close-up images of the planet, though these made it look like a featureless ball.
Now, new images from the JWST’s Near-Infrared Camera (NIRCam) in the 1.4 and 3.0 micron bands of the infrared light spectrum are adding to that body of knowledge in images that are also pleasing to the eye.
The new pictures show Uranus’s unique orientation, which is that its axis of rotation sits almost at right angles to the plane of its orbit. This means that as it revolves about the Sun once every 84 years, one pole is kept in near-total darkness while the other is bathed in unending sunlight for 42 years.
This is of great interest to scientists as the northern hemisphere of Uranus moves from spring to summer in 2028 because this contrast produces extreme weather that can provide new insights into how Earth’s climate works.
The new images show that one part of the planet has a bright area known as the polar cap that appears in the summer and disappears in autumn in either hemisphere. Why this happens is not currently understood. The new images also reveal that the cap has a brighter spot in its center that hasn’t been previously seen. In addition, there is a bright cloud and extended features at the edge of the cap and a second bright cloud outside the cap, which may be a storm or connected to one in some way.
Eleven of Uranus’s 13 known rings and a number of the planet’s 27 known moons can also be seen.