Titan is the only other place in the solar system that has rivers, lakes, and seas. But they are not like those on Earth. They are not composed of water, but of liquid hydrocarbons, especially methane. On the surfaces of these seas, observations from orbit revealed the presence of bright spots that last from a few hours to several weeks. These are the “magic islands” and researchers may have finally discovered what they are.
The first theories after its discovery in 2014 were that waves or bubbles of nitrogen gas or solid materials either float or float to the surface. The former isn't really a Titan feature. The waves are only a few millimeters high, making these liquid bodies particularly smooth.
The new work focused on the interplay between the composition of solids in the atmosphere and what happens when they end up in lakes. Many organic compounds are formed in the dense atmosphere of the moon, and some of them fall into sand hills, rivers and seas. The question is, will they sink? No, as long as it is porous enough.
“I wanted to investigate whether “magic islands” could actually be organic materials that float on the surface, like pumice that can float in water here on Earth before eventually sinking.Lead author Xinting Yu, of the University of Texas at San Antonio, said in a written statement.
Many simple organic molecules land as solids once they form in Titan's atmosphere, including molecules such as benzene. The liquid methane and ethane that make up rivers and lakes have low surface tension, so solids struggle to float on them.
“Looking at the magical islands, they cannot float for a second and then sink,” Yu said. “It should float for a while, but not forever.”
So the model looks at porous solids like pumice, full of holes or tubes into which methane can slowly seep out, allowing those solids to float on top of Titan's liquid properties. Magic islands will form not only in the middle of lakes, but on the shores, where they can grow to a large size before laying eggs and washing away.
“By looking at how long the material would float in each scenario, our study shows this Magic carrots may consist of large pieces of porous organic solids“, the group wrote in the newspaper.
And that's not all. The presence of a solid layer of ice on the surface of lakes and rivers would help explain their smoothness. One solution Two puzzles for the price of one.
The study was published in the journal Geophysical Research Letters.
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