“With the infrared wavelengths and extra sensitivity of Webb, we see more detail, showing how dynamic the atmosphere of Uranus really is.” “When Voyager 2 looked at Uranus, its camera showed an almost featureless blue-green ball in visible wavelengths,” the astronomers said. The planet displays a blue hue in the resulting representative-color image. The new infrared image from Webb’s Near-Infrared Camera (NIRCam) combines data from two filters at 1.4 and 3 microns, which are shown here in blue and orange, respectively. Image credit: NASA / ESA / CSA / STScI / J. This Webb image shows Uranus and six of its 27 known moons (most of which are too small and faint to be seen in this short exposure). “The south pole is now on the ‘dark side’ of the planet, out of view and facing the darkness of space.” “In contrast, when NASA’s Voyager 2 spacecraft visited Uranus it was summer at the south pole.” “Currently, it is late spring for the northern pole, which is visible here Uranus’ northern summer will be in 2028,” Webb astronomers explained. For nearly a quarter of each Uranian year, the Sun shines directly over each pole, plunging the other half of the planet into a 21-year-long, dark winter. This unique tilt causes the most extreme seasons in the Solar System. Uranus is the only solar system planet whose equator is nearly at a right angle to its orbit, with a tilt of 97.77 degrees - possibly the result of a collision with an Earth-sized object long ago. The atmosphere is almost equal to Neptune’s as the coldest in the Solar System with cloud-top temperatures in the minus 218-degree Celsius (minus 360 degree Fahrenheit) range. Winds blow in its deep blue-green atmosphere mainly east to west at speeds up to 900 km per hour (560 mph), in spite of the small amounts of energy available to drive them. 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 is characterized as an ice giant due to the chemical make-up of its interior. And the planet makes a complete orbit around the Sun in about 84 Earth years. Uranus has the third-largest diameter in our Solar System, and is surrounded by 13 faint rings and 27 moons. It was the first planet found with the aid of a telescope, Uranus was discovered in 1781 by the German-born British astronomer William Herschel, although he originally thought it was either a comet or a star. Uranus is the seventh planet from the Sun at a distance of about 2.9 billion km (1.8 billion miles). The planet displays a blue hue in this representative-color image, made by combining data from two filters (F140M, F300M) at 1.4 and 3 microns, which are shown here as blue and orange, respectively. This image of Uranus, captured by Webb’s Near-Infrared Camera (NIRCam) on February 6, 2023, reveals stunning views of the planet’s rings.
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