The mystery of "magic islands" on Saturn's moon Titan may have been solved, according to a study.
The ephemeral phenomena, which temporarily appear as bright spots on radar, were first observed in 2014 by the Cassini-Huygens mission. Since then, researchers have been trying to work out what they are.
Now a study published in the journal Geophysical Research Letters has proposed a potential explanation.
Titan, Saturn's largest moon, has a hazy, orange atmosphere around 50 percent thicker than Earth's that is rich in methane and other carbon-based, or organic, molecules. The surface of the moon is covered with dark dunes of organic material, while it also features lakes and seas consisting of liquid methane and ethane.
It is on these hydrocarbon lakes that the "magic islands" appear in the radar imagery as bright spots that can last a few hours to several weeks, or more, before vanishing.
Previous research had suggested that these phenomena could be phantom islands caused by waves, or real islands made of suspended solids, floating solids, or bubbles of nitrogen gas.
In the latest study, Xinting Yu—a planetary scientist and lead author of the paper at the University of Texas at San Antonio—investigated the relationship between Titan's atmosphere, liquid lakes and the solid materials deposited on the moon's surface to see if it could reveal the causes of the mysterious islands.
"I wanted to investigate whether the magic islands could actually be organics floating on the surface, like pumice that can float on water here on Earth before finally sinking," Yu said in a press release.
"Our team decided to conduct this study out of a fascination with Titan and its complex atmospheric and surface chemistry," Yu told Newsweek. "Titan is unique in our solar system, with its dense atmosphere and liquid hydrocarbon lakes. The 'magic islands' phenomenon observed on Titan has been a subject of intrigue for many years since its discovery in 2014. We aimed to explore this mystery using a theoretical approach, leveraging data on the physical and chemical properties of organics that could be found on Titan's surface."
Titan's unique atmosphere transforms simple gases like methane and nitrogen into more complex organic compounds. These compounds can clump together, freeze and fall onto the moon's surface—including onto the lakes of liquid methane and ethane.
In the latest study, Yu and colleagues explored what happens to these compounds when they reach the surface. They found that most of the organic clumps would land as solids.
The team also looked at what happens when these solids land on Titan's hydrocarbon lakes, finding that these structures could have a porous nature enabling them to float—at least temporarily—under certain certain circumstances.
"Imagine a sponge, full of holes; if the solids are like this, with 25–60 percent of their volume being empty space, they can float. Some solids, like hydrogen cyanide ice, can also float due to surface tension effects. If these conditions are not met, they sink into the lake liquids, adding to the lakebed sediments," the authors wrote in the study.
By looking at how long the materials would float for each scenario, the researchers proposed that floating chunks of porous, frozen, organic solids likely explain the "magic island" phenomenon seen on Titan.
"Our study suggests that [the magic islands] could be floating 'icebergs' of organic material," Yu told Newsweek. "This research offers a potential explanation for one of Titan's most intriguing mysteries, enhancing our understanding of this distant world's environment."
"It also sheds light on the complex interplay between atmospheric chemistry and surface processes on Titan. By understanding these processes, we can gain insights into not only Titan's environment but also broaden our knowledge of planetary science and the behavior of similar extraterrestrial bodies. This could have implications for future missions to Titan, guiding where to look and what to study to unravel more of this moon's secrets."
Update 1/15/24, 8:01 a.m. ET: This article has been updated with comments from Xinting Yu.
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