We just solved the mystery of Titan’s islands in the most unexpected way: organic matter.

• Titan’s seas are perhaps the strangest in the solar system.

• The “magic islands” of these lakes may be accumulations of organic matter.

Saturn’s moon Titan is a unique place in our solar system. This singularity is caused by the large amount of methane in its atmosphere and on the surface of this natural satellite. Methane, which is alternately in liquid and gaseous states, like water on our planet.

New explanation. A recent study has provided a new possible explanation for two of the most intriguing features of Titan’s methane seas: the so-called “magic islands” and the seas’ surprising calm.

Magic Islands. Perhaps the most intriguing of these features are the magical islands. These islands were discovered between 2013 and 2014 by the Cassini-Huygens mission. During one of its flybys of Saturn’s largest moon, the SAR (Synthetic Aperture Radar Imager) the probe’s radar captured a type of island in the region of the Ligeia Mare satellite.

But the most curious thing happened later, when the images showed that the island had disappeared. It was this disappearance that gave rise to the nickname “magic island”.

Icebergs. New research suggests that these islands may be similar to the icebergs we see in Earth’s oceans. With one important difference: the magical islands are not made of solid water, but of organic compounds.

“Water” cycle. Titan is one of the few bodies in our solar system where we can observe a water cycle. Only it is not water, but methane that moves between liquid and gaseous states, between lakes and the atmosphere.

But this hydrocarbon is not only found on the planet’s surface. In the planet’s atmosphere, methane can collide with other compounds, such as hydrogen gas, and condense to form a solid that falls to the moon’s surface.

Two conditions. According to the team responsible for the study, two conditions had to be met for these ephemeral islands to form. First, these solids did not dissolve when in contact with liquid, which was facilitated by the fact that the lakes were already saturated with organic particles.

The second is that they lack the density to sink. By analyzing possible organic compounds, the team found that in order to stay afloat for any length of time, these frozen compounds would have to be porous, like a sponge.

Otherwise, they would sink too quickly under their own weight for us to notice their existence. “For us to see the magical islands, they cannot float for a second and then sink,” Xinting Yu, who led the team responsible for the discovery, explained in a press release. “They must float for a while, but not forever,” the researcher added.

Calm sea. The work also helped to understand another curious feature of Titan: the calmness of its seas. Despite the presence of an atmosphere, the interaction between it and the liquid hydrocarbons on the surface does not lead to the formation of waves, as here on Earth.

The answer may lie in this thin layer of solid material that continually falls onto the lakes, making their surfaces less mobile, the team explains. Details of the work have been published in a journal article. Letters on Geophysical Research.

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Image | NASA/JPL-Caltech/ASI/USGS