As the summer solstice begins to approach on Titan, Saturn’s largest moon, scientists are puzzled by a bright, mysterious object seen in the hydrocarbon lake Ligeia Mare which seems to appear and disappear, earning it the name “magic island.” However, just as soon as it appeared, the “magic island” vanished in the next Cassini spacecraft flyby. A study by an international team has been published in the Journal of Nature Geoscience. The explanation breaks down into four different hypotheses including waves, floating solids, suspended solids and bubbles. The best explanation is that it appears as though after several earth years of winter or spring occurring on the northern part of the moon, summer seems to be bringing with it strong winds that are causing waves, which look like an island in images. Several have now been spotted using the instrumention aboard the Cassini spacecraft. Experts also say the “magic island” spots might be floating or suspended icebergs made up of a frozen mixture of ethane and methane. There is even the possibility that certain conditions on Titan may cause methane-ethane ice to sink during winter months and float in the summer. Other possibilities include gases rising from the sea floor to the surface as bubbles or volcanic vents releasing gasses through the liquid, creating an image that appears as a landmass. Furthermore, the surface of the moon is thought to be covered in organic compounds, including polyacetylene, which has a density low enough to allow it to float, which means it might be suspended below the surface of the sea.
The spots are the initial hints that Titan’s lakes may be stirring in response to summertime warmth, quite similar to the way lakes on Earth respond to changing seasons. Scientists are interested in the effects various processes, such as rain, wind and tides will have on the methane and ethane lakes of Titan. Experts are comparing geological processes with those here on Earth. Until now, the lakes were incredibly smooth, a puzzling fact due to Titan’s other wind-driven features like dunes. Researchers hope that as the summer solstice approaches that “magic island” may appear on Titan, which will help determine if the active processes are powered by the sun. Heat and moisture rising from the surface of the lake could even potentially trigger small-scale tropical cyclones, similar to Earth’s hurricanes. Scientists believe it may ultimately even help to explain our own liquid environments better here on Earth.
Far milder than Earth’s dramatic temperature differences between seasons, temperatures during the summer solstice will only be a few degrees warmer than in winter, when Titan’s surface temperature is just below methane’s freezing point, -297 degrees Fahrenheit (-183 degree Celsius). However, Titan is expected to become a much more dynamic body as it reaches the peak as it approaches the summer solstice in May 2017, which could cause the appearance of the “magic island.” Titan is the only body in the solar system besides Earth to have lakes, rivers and small seas. Titan functions on a 30-year season cycle. The surface of the moon is so cold that liquid water cannot exist there. Its mountains and dunes are made of ice instead of rock. Titan also has a very dense atmosphere, with qualities not so different from a primordial Earth containing all the ingredients for life, which is why scientists are so interested in the methane and ethane cycle of precipitation. Amongst the “magic island” of Titan may exist the building blocks for life.
By Samantha Levy