Footsteps of the Neptune image released in 2022, NASA’s James Webb Space Telescope has captured a stunning image of the solar system’s other ice giant, the planet Uranus. The new image includes dramatic rings and bright features in the planet’s atmosphere. The Webb data demonstrate the observatory’s unprecedented sensitivity to the faintest dusty rings ever imaged by only two other instruments: the Voyager 2 probe during its 1986 flyby of the planet and the Keck Observatory with Advanced Adaptive Optics.
Image of the solar system’s other ice giant
The seventh planet from the Sun, Uranus, is unique: it rotates on its side at an angle of roughly 90 degrees from the plane of its orbit. This causes extreme seasons, as the poles of the planet experience many years of constant sunlight followed by an equal number of years of complete darkness. (Uranus takes 84 years to orbit the Sun.) Currently, it is late spring for the North Pole visible here; Uranus’ northern summer will be in 2028.
In contrast, when Voyager 2 visited Uranus, it was summer at the south pole. The South Pole is now on the “dark side” of the planet, out of sight and facing the darkness of space. This infrared image from Webb’s Near-Infrared Camera (NIRCam) combines data from two 1.4- and 3.0-micron filters, shown here in blue and orange. The planet displays a blue tint on the resulting representative color image.
When Voyager 2 looked at Uranus, its camera showed a nearly shapeless blue-green ball in visible wavelengths. Thanks to the infrared wavelengths and extraordinary sensitivity of the Webb, we are seeing more detail that shows how dynamic Uranus’ atmosphere really is.
To the right of the planet is an area of ​​brightness at the pole facing the Sun, known as the polar cap. This polar cap is unique to Uranus it appears to appear when the pole enters direct sunlight in the summer and disappears in the fall; this Webb data will help scientists understand the currently mysterious mechanism.
Webb revealed a surprising aspect of the polar cap: a subtle enhanced brightening in the center of the cap. The sensitivity and longer wavelengths of Webb’s NIRCam may be why we can see this enhanced polar feature of Uranus when it has not been seen as clearly with other powerful telescopes such as the Hubble Space Telescope and the Keck Observatory.
A bright cloud lies at the edge of the polar cap as well as several fainter extended features just beyond the edge of the cap, and a second very bright cloud can be seen at the left edge of the planet. Such clouds are typical of Uranus at infrared wavelengths and are likely related to storm activity.
This planet is characterized as an ice giant due to the chemical composition of its interior. Most of its mass is thought to be a hot, dense fluid of “icy” materials – water, methane and ammonia – above a small rocky core.
Uranus has 13 known rings, and 11 of them are visible in this Webb image. Some of these rings are so clear with Webb that when they are close together they appear to merge into a larger ring. Nine are classified as the planet’s main rings, and two are fainter dust rings (such as the diffuse zeta ring closest to the planet) that were not discovered until the Voyager 2 flyby in 1986. Scientists expect that future images of Webb Uranus will reveal two faint outer rings, which were discovered by HST during the ring plane transition in 2007.
Webb also captured many of Uranus’ 27 known moons (most of which are too small and faint to see here); the six brightest are identified in the wide-angle image. This was just a short, 12 minute exposure image of Uranus with just two filters. It’s just the tip of the iceberg of what Webb can do in observing this mysterious planet.
In 2022, the National Academies of Sciences, Engineering, and Medicine identified Uranus science as a priority in its 2023–2033 Ten-Year Survey of Planetary Science and Astrobiology. More studies of Uranus are now underway, and more are planned in Webb’s first year of scientific operation.
Written by: Vaishali Verma
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Reference: https://www.sciencedaily.com/releases/2023/04/230406114006.htm
