Scientists have made the incredible discovery that Saturn's moon Titan has an atmosphere more similar to Earth's than was previously believed.
A team of researchers looked at data gathered over several years by the international Cassini probe, and found interactions in the moon's atmosphere create winds of hydrocarbons and nitriles that move away from the Polar Regions and into space, University College London reported. These winds are very similar to ones that have been observed coming from Earth's Polar Regions. Titan is the only known moon in our solar system with a rocky surface as well as rivers and seas.
"Titan's atmosphere is made up mainly of nitrogen and methane, with 50 [percent] higher pressure at its surface than on Earth," said Andrew Coates, a researcher at UCL Mullard Space Science Laboratory who led the study. "Data from CAPS proved a few years ago that the top of Titan's atmosphere is losing about seven tonnes of hydrocarbons and nitriles every day, but didn't explain why this was happening. Our new study provides evidence for why this is happening."
Hydrocarbons are a class of molecules that include methane, petrol, and natural gas. Nitriles are molecules with nitrogen and carbon bound together. The winds were found to be a product of interactions between sunlight, the solar magnetic field and the molecules in the upper atmosphere.
"Although Titan is ten times further from the Sun than Earth is, its upper atmosphere is still bathed in light," Coates said. "When the light hits molecules in Titan's ionosphere, it ejects negatively charged electrons out of the hydrocarbon and nitrile molecules, leaving a positively charged particle behind. These electrons, known as photoelectrons, have a very specific energy of 24.1 electronvolts, which means they can be traced by the CAPS instrument, and easily distinguished from other electrons, as they propagate through the surrounding magnetic field."
Unlike Earth, Titan does not have its own magnetic field and instead is surrounded by the rapidly rotating one belonging to Saturn. Fly-bys of the moon revealed photoelectrons far from the object, which was most likely made possible by the ease at which they can travel along the magnetic field lines. These negatively-charged photoelectrons spread throughout Titan's ionosphere, creating an electrical field that is strong enough to pull positively charged hydrocarbon and nitrile particles from the atmosphere and create the observed Polar winds.
The findings were published in a recent edition of the journal Geophysical Research Letters.
