Feeling hemmed in by winter? Held back by cold? Time to consider a Web vacation to Saturn’s largest moon Titan. One thing’s for sure, the place has a lot of atmosphere. Thickly cloaked in a blanket of air composed of 98% nitrogen, Titan’s atmosphere is so dense (1.45 times that of Earth) and gravity so weak, that humans could fly by donning a pair of homemade wings and flapping like a bird. Since many of us have dreamed of flying on our own power, who would have guessed Titan would be the closest outpost to offer that opportunity.
Titan spans 3,200 miles (5,150 km) across or almost exactly 1 1/2 times the size of the moon. Besides nitrogen, the atmosphere also contains 1.4% methane and a smattering of hydrocarbons like ethane and propane. Ultraviolet light from the sun cooks these into an orange, smoggy moon-wide haze; to image the surface requires infrared cameras and telescopes that can “see” in haze-busting infrared light.
Today it’s summer in the orange moon’s northern hemisphere and winter in the south. During Cassini’s long stay at Saturn (since 2004), it’s seen seasonal changes on Titan. When it first arrived, a hood of high clouds named the north polar vortex, swirled above the north pole. A similar hood – the south polar vortex – recently formed over the south polar region. Scientists believe it’s related to the beginning of southern winter.
The vortex spins around once every 9 hours hours, some 42 times faster than Titan’s 16-day rotation period, floats above the regular cloud deck, high enough for its curving edge to catch the last of the sun’s rays. A beautiful sight!
According to NASA, scientists think these new images show open cell convection – air sinks in the center of the cell and rises at the edge, forming clouds at cell edges. No one knows exactly what creates the vortex,but it does appear to be a seasonal feature.
Besides a thick atmosphere, methane clouds and hydrocarbon haze, Titan dazzles with thousands of lakes filled with liquid natural gas – ethane and methane – that range in size from pond-size to larger than Lake Superior. Only Titan’s extremely cold surface temperature of -290 F (-179 C) and substantial atmospheric pressure can turn what are normally gases on Earth into liquids and keep them that way.
A most fascinating world where humans might one day fly of their accord and even ply boats across hydrocarbon lakes beneath a peach-colored sky.