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As recently as 2004, nosotros knew Saturn's largest moon Titan basically every bit a fuzzy orange blob, a cold, Mercury-sized satellite of a afar gas behemothic. Scientists knew it had a dense, nitrogen-rich atmosphere — the just one that nosotros knew of, other than our own — but they weren't sure about how the temper was organized, nor how the planet's surface dynamics went. Now Cassini has changed all that. In a recently released written report worthy of NASA'south Titan Hall of Fame, Cassini peers through the nitrogen fog at the surface, and specular highlights and radar measurements confirm our predictions. Titan is covered in surface features that are just similar what we have on World… but a whole lot different, too.

It's hard to depict Titan without getting a lilliputian breathless — the place is a piffling like Earth'south "upside downwardly." Earth is a moisture, temperate planet, with continents bounded by surface water, clouds, and a water bicycle. Titan is so cold that information technology has liquid methane, and yet it likewise has clouds and surface atmospheric condition that imply a hydrocarbon cycle. There are lakes of marsh gas about Titan's n pole, and closer to its equator prevarication vast deserts of hydrocarbon dunes, made of granules of h2o water ice coated in dark hydrocarbons that autumn from the sky like pelting. Possibly upside-down-iest is the fact that at that place'south a hidden interior bounding main of h2o and ammonia that covers the entire moon — submerged beneath the thick rime of frozen organic chemical science. It'due south all topsy-turvy.

As hydrocarbon pelting turns into rivers and carve through the surface, canyons proportionate to our Yard Canyon run with flowing methane. New photos from Cassini show us rivers of methane and ethane that stretch for hundreds of miles before they empty into Titan's northerly sea, Ligeia Mare. And Cassini has been watching the transition from fall to wintertime at Titan's southward pole: Seasons on Titan last for seven years or so, and winter is coming. In fact, this is the first time anyone has ever seen the onset of a Titan winter. "We're monitoring the weather on Titan, watching for predicted methane rainstorms at the north pole," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory.

"I am intrigued by how many features on Titan's surface are remarkably Earth-similar," said Spilker, "including hydrocarbon rivers, lakes and seas, and equatorial dunes, with liquid marsh gas playing the role on Titan that h2o plays on Globe."

Observations like the ones we go from Cassini and Huygens are important because they bear out our expectations about what we tin safely infer from spectrographic readings of remote worlds. Before Cassini, we knew very little about Titan, except that nosotros had seen nitrogen in its atmosphere with a spectrograph. Cassini's instrumentation non only confirmed our predictions of nitrogen, only gave us the power to peer through the obfuscating atmosphere to the surface beneath — and beamed back a gallery of visual imagery to bring it all together. With a robust theory of Titan'south limerick and chemic dynamics, we'll exist able to keep digging deep into our solar system's history — and also rest more than securely on the idea that we tin point a prism at a planet light-years away, and nonetheless gather useful data that reflects reality.

Titan's planetary chemistry also poses some fascinating questions about the origin of life, and what extraterrestrial life might look similar on the fine scale. Retrieve nearly this. The unabridged chemistry of life on earth depends on how life probably arose in seawater, a polar solvent. What sort of fantastical information-transfer biopolymer might life on a nonpolar planet employ? Imagine a Deoxyribonucleic acid analog from a hydrocarbon planet, where the information is encoded in benzene rings and stereochemistry. If nosotros can apply Titan to advance our own understanding, nosotros could put along answers to some big questions about life, the universe, and everything.