The James Webb Space Telescope pointed towards the enigmatic Uranus and, as always, did not disappoint with the result. NASA’s powerful instrument, equipped with the best technology available so far, captured like never before the series of 13 rings of the ice giant and several of its moons.
Until this year, Uranus had only been photographed directly twice. The first photo was taken by the Voyager 2 spacecraft — in 1986 — and then by the Earth-based Keck Observatory — the first time, in 2004. The planet was for us a blue ball, placid and solid. But James Webb transformed this image.
The powerful telescope gave us its first postcard of Uranus last April. An impressive image in which, however, only 11 of his 13 rings could be seen. The other two rings of Uranus, the outermost ones, had not been captured because they are very faint.
The James Webb has now taken advantage of its infrared light sensors to show us more details than what he had revealed before. And finally, it exposes the last two elusive rings of Uranus, the seventh planet in our system from the Sun. He also imaged many of the 27 known moons and even saw some small moons inside the rings.
Other new details that NASA showed have to do with the seasonal cloud cover at the planet’s north pole. Compared to Webb’s image from last April, some aspects of the cap are now easier to see. These include the bright white inner cap and the dark lane at the bottom of the polar cap, toward lower latitudes.
Uranus, the cold giant with many rings
Uranus is very cold and windy. It is distinguished by a rarity: It rotates at an angle of almost 90 degrees with respect to the plane of its orbit. This tilt makes it appear that the planet is turning on its side. Because of this way of spinning, Uranus has the most extreme seasons in the solar system.
For almost a quarter of each Uranian year, the Sun shines on one pole, plunging the other half of the planet into a dark winter that lasts 21 years. And it is that A day lasts a little more than 17 hours, but a year is equivalent to 84 years on Earth.
In the new James Webb image, several bright storms can be seen near and below the southern edge of the polar cap, NASA explained in a statement. The number of these storms, the frequency and where they appear in Uranus’s atmosphere could be due to a combination of seasonal and meteorological effects.
The polar cap appears to become more prominent as the planet’s pole begins to point toward the Sun, as the solstice approaches and it receives more sunlight. Uranus will reach its next solstice in 2028. That’s why astronomers are eager to observe any possible changes in the structure of these features.
The atmosphere is composed primarily of hydrogen and helium, but also includes large amounts of water, ammonia, and methane. Uranus is greenish blue because, precisely, it has large amounts of methane that absorb red light, but allows blues to be reflected into space.
The details exposed thanks to the James Webb technology, such as those of the nearby Zeta ring, will be key to planning future missions to Uranus. The planet also serves as a sample for scientists to study. the almost 2,000 exoplanets of similar size that have been discovered in recent decades.