Saturn’s moon Titan is known to possess liquid seas and during a recent flyby by NASA’s Cassini mission a mysterious formation appeared to rise from the depths. But then, just as mysteriously as it appeared, “Magic Island” (as it has become known by planetary scientists) vanished.
In a new paper published in the journal Nature Geoscience on Sunday, an international team of researchers have arrived at some explanations for Magic Island. Sadly, none of them point to an extraterrestrial Atlantis.
Titan is the only moon in the solar system to have a thick atmosphere. However, the Saturnian moon is so cold that liquid water cannot exist on its surface. The large bodies of liquids that do exist are composed of methane and ethane — two organic compounds that have very low freezing points and can exist in a liquid state in Titan’s frigid environment.
Like Earth’s water cycle, Titan’s atmosphere is known to have a methane and ethane cycle, where bodies of the liquids accumulate in seas, evaporate, condense and precipitate as a very alien rain. Rivers cut valleys into the landscape and the seas give way to landmasses awash with hydrocarbons. It’s for these reasons that scientists are fascinated with this little word and its hazy atmosphere — it is not so dissimilar from a primordial Earth containing the ingredients for life, only in different quantities and much further away from he sun.
So it was with great interest when, on July 10, 2013, Cassini beamed back images of Ligeia Mare, a sea located near Titan’s north pole, a bright feature — looking like an island — appeared from the depths. But then, during a follow-up flyby only days later on July 26, the island had gone. Further Cassini flybys confirmed that Magic Island had vanished.
“‘Magic island’ is a colloquial term that we use within the team to refer to this,” Jason Hofgartner, astronomer and lead author from Cornell University, Ithaca, New York, told BBC News. “But we don’t actually think it’s an island.”
So what was it?
Magic Island is “best explained by the occurrence of ephemeral phenomena such as surface waves, rising bubbles, and suspended or floating solids,” the researchers write in their publication. In short, they think the feature was caused by an increase in solar energy as the Titan approaches summer in its 30 year seasonal cycle, making the region a more dynamic place.
“Right now, Titan is basically half way between the vernal equinox (August 2009) — at the beginning of spring — and the summer solstice, the start of summer. It’s roughly equivalent to what we would consider the beginning of May,” said Hofgartner. “As Titan approaches its summer, more of the sun’s energy is being deposited in the northern hemisphere.”
One explanation centers around the occurrence of huge chunks of methane-ethane ice, similar to Earth’s icebergs, that float as the atmosphere warms but sinks as it cools. Another possibility is a mass of organic material that is less dense than the surrounding liquid, allowing it to float or be suspended just below the surface.
Previous observations have shown that Titan’s seas can be whipped up sufficiently by surface winds to cause waves and ripples, glinting in sunlight, so this is another possible answer. Volcanic vents releasing gasses through the liquid may also be to blame, creating a disturbance that, from Cassini’s perspective, looks like a landmass.
Unfortunately, the mechanisms behind Magic Island will likely remain a mystery until we actually send a mission to investigate Titan’s seas.
“These are clearly observations that are close to the limit of detectability — and therefore very difficult to interpret. But it looks like something is going on in Ligeia Mare. Titan surprises us at every turn,” John Zarnecki, of the Open University in Milton Keynes who worked on previous studies into Titan’s rippled seas, told BBC News.
“Is this feature showing us floating solids or gases erupting at the surface — or a phenomenon that we haven’t thought of? After all, we tend to think in terms of Earth-like phenomena. But based on this so far sparse data, any suggestion is likely to be little more than speculation until we get some more supporting information.”
Source: BBC News