What could it be?!
Scientists once again are scratching their heads over a mysterious surface feature on the Saturn moon Titan that some are calling a "magic island."
The feature -- observed in a large sea on Titan known as Ligeia Mare -- was first spotted in images taken by NASA's Cassini spacecraft in July 2013. Photos snapped of the area over the ensuing months failed to show the feature, but it reappeared in images from a Cassini flyby on August 21, 2014.
Between the two sightings, the feature doubled in size from 30 to 60 square miles (see below).
These three images, created from Cassini Synthetic Aperture Radar (SAR) data, show the appearance and evolution of a mysterious feature in Ligeia Mare, one of the largest hydrocarbon seas on Saturn's moon Titan.
“Science loves a mystery, and with this enigmatic feature, we have a thrilling example of ongoing change on Titan," Stephen Wall, deputy leader of Cassini's radar team at NASA's Jet Propulsion Laboratory, said in a written statement. "We’re hopeful that we’ll be able to continue watching the changes unfold and gain insights about what’s going on in that alien sea.”
The researchers say they're confident the feature isn't simply a glitch in their data. Rather, they think it might be evidence of bubbles, surface waves, solids floating on or just below the surface, or "perhaps something more exotic," according to NASA. They believe the "magic island's" appearance may be linked to the onset of summer in Titan's northern hemisphere.
Cassini was launched in 1997 and entered into orbit around Saturn in 2004. The probe has conducted flybys of Titan -- which scientists consider to be one of the most Earth-like worlds -- for 10 years.
While some scientists believe Titan's liquid seas of methane and ethane suggest the alien world may be habitable, the researchers say it's unlikely the strange feature is linked to any sort of life form.
"There's no reason to suspect this is a signal for biology," Jason Hofgartner, a planetary scientist at Cornell University and one of the researchers involved in the mission, told NBC News. "But in general, more energetic processes may enhance the suitability for life on Titan."