It's the outer space case of the vanishing moon island.

That's what astronomers at the National Aeronautics and Space Administration are calling an apparent land mass surrounded by one of the liquid methane spans on Titan, Saturn's largest moon -- the mass seems to have disappeared mere weeks after it was first spotted.

The cosmic mystery rose from images of the moon's Ligeia Mare, or large sea, captured in July by NASA's robotic Cassini spacecraft, which was launched in 1997 and sent into orbit around Saturn in 2004.

The craft's radar captured images of what researchers say was a bright, small island on the methane surface that was not visible in previous images.

The island was gone in images taken only a couple of weeks later.

Details of the here-today-gone-tomorrow encounter have been published in the journal Nature Geoscience.

The scientific team from Cornell University that did the research calls the find a "magic island," despite the fact that the vanishing act was probably caused by weather or some other natural phenomenon on the moon, which has earth-like features, such as mountains, lakes and dunes, but is not known for sudden landscape changes.

"Likely, several different processes, such as wind, rain and tides, might affect the methane and ethane lakes on Titan. We want to see the similarities and differences from geological processes that occur here on Earth," Cornell planetary sciences graduate student Jason Hofgartner, the study's lead author, said in a CNET report. "Ultimately, it will help us to understand better our own liquid environments."

Meanwhile, a study out of the Southwest Research Institute in San Antonio, Texas, and funded by both NASA and the European Space Agency has found firm evidence that the nitrogen in Titan's atmosphere originated in conditions similar to the cold birthplace of the most ancient comets from the Oort cloud, the cloud of relatively small objects circling at the boundary of the sun's gravitational field.

In other words, Titan did not emerge from the heated disk of material scientists believe surrounded Saturn when it was forming.

That implies that the moon was born from the same cold cloud of gas and particles from which the sun was formed.

The insights into Titan's origins were published this week in The Astrophysical Journal Letters.