This image of a crescent-shaped Uranus, taken on January 24, 1986 by the NASA spacecraft Voyager 2, reveals the icy blue atmosphere of the planet. Despite the near-by fly of Voyager 2, the composition of the atmosphere remained a mystery until now.
Credit: NASA / JPL-Caltech
There's a lot of really foul-smelling stuff around Uranus.
The clouds in Uranus' upper The atmosphere consists mainly of hydrogen sulfide, the molecule that makes rotten eggs so stinky, as a new study suggests.
"If an unfortunate person ever fell through the clouds of Uranus, they would be confronted with very unpleasant and olfactory conditions." Study leader Patrick Irwin, from Oxford University in England, said in a statement.
But this idiosyncratic pioneer would have bigger problems, he added, "asphyxiation and exposure in the negative 200 degrees Celsius [minus 328 degrees Fahrenheit] atmosphere, made up mainly of hydrogen , Helium and methane, would take its toll on the smell for a long time.
Researchers have long wondered about the composition of the clouds in the sky of Uranus – especially if they are dominated by ammonia ice, as in Jupiter and Saturn or by hydrogen sulfide ice – the answer has been elusive because it is difficult is to make observations with the required detail about the distant Uranus. (Jupiter and Saturn are not only closer to Earth, they have also hosted special orbiter missions.) Uranus was only visited once – a brief flyby by NASA's Voyager probe 2 in January 1986.)
Irwin and his colleagues studied Uranus' air with the near-infrared integral field spectrometer (NIFS), an instrument on the 26-foot (8 meter) Gemini North Telescope in Hawaii.NIFS tested the sunlight reflected from the atmosphere directly above the Uranus cloud surfaces and discovered the signature of hydrogen sulfide.
"Only a tiny amount remains as a whole saturated vapor above the clouds, "co-author Leigh Fletcher of the University of Leicester in England said in the same statement. "And so it's so challenging to capture the signatures of ammonia and hydrogen sulfide over Uranus's cloud cover, and Gemini's superior abilities finally gave us that happy break."
Neptune's clouds are likely to resemble those of Uranus, the researchers said. The big difference between the clouds of these two "ice giants" and those of Jupiter and Saturn probably goes back to the educational environments of the worlds: Uranus and Neptune merge much farther from the Sun than the two gas giants.
"During the formation of our solar system, the equilibrium between nitrogen and sulfur – and thus ammonia and the newly discovered hydrogen sulphide from Uranus – was determined by the temperature and location of the [a] planetary formation," said Fletcher.
Study was published online today (April 23) in the journal Nature Astronomy