Uranus is one of the most fascinating places in the Solar System, an ice giant with a mass 14.5 times the Earth that scientists find difficult to understand. Uranus is blue-green in color due to large amounts of methane, which absorbs the red component of light and reflect the blue component back into space. The James Webb Telescope with his resolution tries to reveal hidden aspects of the planet.
A new look at Uranus 👀
— NASA (@NASA) December 18, 2023
@NASAWebb observed the unique planet in new detail, highlighting features such as rings, moons, storms, and a seasonal polar cap. Webb’s infrared vision and sensitivity expand on a version taken by the telescope earlier this year: https://t.co/de3EhIqvvJ pic.twitter.com/TRVQX1yuIc
Uranus: a mysterious planet
Uranus is the seventh planet by distance from the Sun, and despite it is not the last, it’s still the coldest with a temperature on its clouds that goes down to -216 Celsius. This has raised quite a few questions over the years about this icy world.
A very special feature of this planet is that it rotates on its side at an angle of 99.77 degrees and it is not known for sure what caused this inclination. This has several effects, for example, the period between sunrise and sunset on Uranus lasts 42 years. The planet in fact takes 84 years to make a complete revolution around the Sun but due to its inclination one pole remains for 42 years exposed to light and then 42 years in darkness.
Consequently, one would expect the pole exposed to light to be much hotter than the opposite pole that has been in shadow for decades, but instead the Voyager 2 probe on its passage in 1986 measured similar temperatures between the two poles, another oddity of this planet.
The inclination of Uranus also causes extreme seasonal changes resulting in storms with winds reaching 820 km/h. A further peculiarity concerns the magnetic field, which has a completely different inclination from the axis of rotation of the planet itself, precisely 59 degrees of inclination. This causes aurorae far from the planet’s geographic poles and a very intricate magnetic field that the planet leaves behind during its orbit. It is a planet as fascinating as it is unsuitable for life.
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A detailed close-up of Uranus
Planets such as Uranus are difficult to photograph with good detail. This is because their size-distance ratio is very low compared to that of other celestial bodies outside the Solar System such as nebulae and other galaxies. In addition, Uranus rotates around its axis in 17 hours, this makes it difficult for observatories to capture one simple image of the entire planet because storms and other atmospheric features, move visibly within minutes. This image combines several longer and shorter exposures of this dynamic system to correct for those slight changes during the observing time.
In visible colors, Uranus appears as a quiet blue ball. However, thanks to Webb’s sensitivity to infrared wavelengths, a strange and dynamic scenario emerges, revealing intriguing details of its unique atmosphere.
This close-up of Uranus obtained by the NIRCam (Near-Infrared Camera) of NASA’s James Webb Space Telescope shows the planet and its rings with new clarity. Webb captured Uranus’ inner and outer rings including the elusive Zeta ring, the extremely faint ring closest to the planet.
Notable among the most stunning features is the seasonal north polar cap. Compared with previous images, this view offers more defined details, including the bright white inner canopy and a dark band at the bottom, extending into the lower latitudes.
Also visible are bright storms present near and below the southern boundary of the polar cap. Astronomers are fascinated by the questions these storms raise: how many are there, how often do they occur, and where do they occur in Uranus’ atmosphere? Webb will be a valuable ally in unraveling the intricate seasonal and meteorological effects that shape the planet’s storms, providing information to decipher Uranus’ complex atmosphere.
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Uranus Wide-Field Image
Looking at the wide image it is possible to see the planet with a series of distant galaxies in the background. Also visible in this image are 14 of the 27 moons that rotate around Uranus: Oberon, Titania, Umbriel, Juliet, Perdita, Rosalind, Puck, Belinda, Desdemona, Cressida, Ariel, Miranda, Bianca, and Portia. These are the blue dots surrounding the planet’s rings.
Uranus’ moons play an important role in its rings. In the ring system of Uranus, moons are not only a cosmic spectacle but also an important modeling force. Because of their gravity, these moons maintain order among the ring particles, preventing chaotic dispersion. The result is precise structure and defined divisions in the rings of the icy planet, which highlight the critical role of gravitational forces in modeling such astronomical systems.
Finally, Uranus can also serve as a reference point for the study of the nearly 2,000 exoplanets of similar size discovered in recent decades. This “exoplanet in our backyard” can help astronomers understand how planets of this size work, what their meteorology is like, and how they formed. This, in turn, can help us understand our Solar System putting it in a larger context.
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