What Does Uranus Smell Like?

     Readers for whom English is not a first language probably will not appreciate the pun here. In English, Uranus is pronounced the same as "your anus," the anus being the opening at the end of the alimentary canal through which solid waste matter leaves the body. The opening also has other more crass names. Hence, when a few headlines read "Uranus Smells Like Rotten Eggs" it evoked a chuckle. 
     A study by lead author Patrick Irwin, of Oxford University in England, concluded that the clouds in Uranus' upper atmosphere are composed largely of hydrogen sulfide, the molecule that makes rotten eggs so stinky. 
     Let me remind you that flatus (aka farts) is composed of about 59 percent nitrogen, 21 percent hydrogen, 9 percent carbon dioxide, 7 percent methane and 4 percent oxygen. About one percent of a contains hydrogen sulfide gas and mercaptans, which contain sulfur, and the sulfur is what makes for the stink. 
     Hydrogen sulfide gas causes a wide range of health effects. One is primarily exposed to hydrogen sulfide by breathing it. The effects depend on how much hydrogen sulfide you breathe and for how long. 
     Exposure to very high concentrations can quickly lead to death. Some people who breathed in levels of hydrogen sulfide high enough to become unconscious continue to have headaches and poor attention span, memory, and motor function after waking up. The effect called knockdown (rapid unconsciousness) often results in falls that can seriously injure the worker. 
     Problems with the cardiovascular system have also been reported at high exposures. People who have asthma may be more sensitive to hydrogen sulfide exposure. That is, they may have difficulty breathing at levels lower than people without asthma. 
     Hydrogen sulfide is a highly flammable, explosive gas; the explosive range of hydrogen sulfide in air is 4.5 to 45.5 percent. In addition, hydrogen sulfide gas burns and produces other toxic vapors and gases, such as sulfur dioxide. 

     In addition to exposure to hydrogen sulfide in the air, exposure to liquid hydrogen sulfide can cause "blue skin" or frostbite. If clothing becomes wet, avoid ignition sources, remove the clothing and isolate it in a safe area to allow it to evaporate. 
     Irwin states that if a person descended through Uranus' clouds, they would be met with very unpleasant and foul smelling conditions. The clouds in Uranus' upper atmosphere are composed largely of hydrogen sulfide, the molecule that makes rotten eggs so stinky. 
     But wait! There's more! Exposure to the minus 328 degree Fahrenheit atmosphere (negative 200 degrees Celsius) wold kill you long before the gases in the atmosphere suffocated you. 
     The composition of the clouds high up in Uranus' sky has proved elusive, because it's tough to make observations with the required detail because Uranus is so far away...1.6 billion miles (2.6 billion kilometers) at the closest. The closest we ever got to it was a brief flyby by NASA's Voyager 2 probe in January 1986. 
     Irwin and his colleagues studied Uranus' air using the Near-Infrared Integral Field Spectrometer (NIFS), an instrument on the 26-foot (8 meters) Gemini North telescope in Hawaii and spotted the signature of hydrogen sulfide. Above the clouds only a tiny amount remains and that is why it is so challenging to capture the signature. It is he superior capabilities of the Gemini telescope finally gave them the capability to make their observations.