“The majority of Jupiter is hydrogen and helium which don’t smell really. There is ammonia which might smell a bit like cat wee or sweat and the hydrogen cyanide might have a bit of an almond-like smell (like marzipan) but commonly doesn’t have a smell at all.” Dr Louisa Preston, Dept of Space & Climate Physics at University College London, and Planetary Groups' Habitability Lab at the Mullard Space Science Laboratory.
“I think Jupiter's atmosphere might have quite an oily smell owing to hydrocarbons/tholins produced by UV-driven Miller-Urey-type reactions that give the clouds their orange/brown colours.” Ian Crawford, Professor of Planetary Science and Astrobiology at Birkbeck University of London, and Chair of Sub-Commission B3 (The Moon) of the Committee on Space Research (COSPAR).
According to NASA, the composition of Jupiter’s atmosphere is approximately 89.8% molecular hydrogen and 10.2% helium; also methane, ammonia, hydrogen deuteride, ethane and water in parts per million and aerosols of ammonia ice, water ice and ammonia hydrosulphide.
As depth increases, we expect three main cloud layers with different temperature gradients, and chemistry changing from ammonia at the top, to ammonium hydrosulphide and water deeper down. We can observe the upper ammonia clouds and many belts (dark bands) and zones (light bands) that run parallel to the Equator, as well as the iconic Great Red Spot, a giant storm that is bigger than the Earth and has been raging for hundreds of years.
Pressure also increases with depth and the atmosphere gradually transitions into liquid hydrogen first, and metallic hydrogen deeper down.
The reddish and orange colours that we observe on the haze layers above the main clouds, are thought to be caused by the presence of organic molecules such as polycyclic aromatic hydrocarbons (PAHs) including ethane and acetylene. These molecules are produced by the chemical reactions of methane interacting with ultraviolet radiation, and are the type of molecule that we would smell, if such a thing were possible on Jupiter.
As well as PAHs, there was some speculation in the past about small amounts of hydrogen cyanide in the deeper layers of the Jovian atmosphere, a molecule that was observed following the cometary impact of Shoemaker-Levy 9 in 1994. It is the smell of this molecule that captivated our perfumer’s mind, because is often described as having a faint smell of bitter almonds, although not everybody can detect this odour.
MORE ABOUT JUPITER
Average distance from the Sun: 778.3 million km
Length of year: 4,333 Earth days
Length of day: 9.9259
Equatorial radius: 71,492 km
Mass: 1.898 × 10^27 kg (317.8 Earth masses)
Surface gravity: 24.79 m/s2
Mean density: 1,326 kg/cm3
Escape velocity: 59.5 km/s
Surface temperature: -145 °C. It gets much hotter with depth and, according to NASA, the temperature at the core may reach 24,000 °C!
Number of moons: 95
Atmospheric pressure at surface: the surface of Jupiter is defined as the point where the atmospheric pressure is equal to that of Earth.
Jupiter has a ring system, but the rings are very difficult to see unless they are back-lit by the Sun.
Jupiter’s magnetic field is about 20 times stronger than Earth’s.
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