In an unprecedented study lasting two decades, scientists have gained new insights into the composition and dynamics of Uranus‘ atmosphere. This was made possible by the Hubble telescope.
Uranus is a strange and mysterious world that moves around the Sun, tilted on its side. When Voyager 2 flew past it in 1986, it took a close-up photo of the planet. There was something it saw that resembled a blue-green billiard ball without any distinguishing features.
Fortunately, thanks to the Hubble telescope, astronomers have been able to study the seventh planet without sending new instruments to it. It observed the planet four times: in 2002, 2012, 2015 and 2022. Hubble data has provided unique insights into the composition and dynamics of its atmosphere and how it responds to changes in the amount of sunlight.
Uranus’ atmosphere is composed mostly of hydrogen and helium, with small amounts of methane and traces of water and ammonia. It is methane that gives Uranus its blue color, absorbing the red wavelengths of sunlight.
Hubble found that unlike the gas giants Saturn and Jupiter, methane is not evenly distributed across Uranus. Its reserves are severely depleted near the poles. This depletion remained relatively constant for two decades. However, the structure of the aerosol and haze has changed dramatically, significantly increasing in brightness in the north polar region as the planet approaches the northern summer solstice in 2030.
The fact is that it takes Uranus just over 84 Earth years to make one orbit around the Sun. Thus for two decades the Hubble team has only seen mostly spring in the Northern Hemisphere. Telescope data indicate complex atmospheric circulation patterns during this period, including a downward flow in the polar regions and an upward flow in other regions.
Observational results also indicate a direct relationship between aerosols (haze) in the atmosphere of Uranus and the amount of sunlight. The more light that reaches Uranus, the stronger the concentration of haze becomes — and vice versa.
We’ve previously covered how the oscillations of Uranus’ moons can help reveal their hidden oceans.
According to NASA
