9 October 2014

Beyond the rings of Saturn

The hexagon on Saturn is a six-sided hurricane sixty miles deep [and with a circumference that could accommodate] four Earths. It’s ringed by winds of ammonia and hydrogen blowing at 220mph. The storm was seen by the Voyager spacecraft when they passed by in the early 80s. That was the last time until recently that sunlight graced the north pole of Saturn, which takes 30 of our years to make one circuit of the Sun. Soon after the Voyagers departed winter descended. Saturn’s rings tipped away from us, plunging the north pole into fifteen years of darkness. Without sunlight, astronomers were limited to infrared images. They showed the hexagon was still there. But what is it? 
The hexagon is a narrow jet stream that circles the north pole. Researchers think that friction with the clouds on either side of it creates eddies — mini-storms — that push the jet stream into a wave-like shape as it spins around. By spinning water columns at different speeds, scientists have been able to reproduce the six-sided pattern in the lab. In January 2009 the sun began its slow rise in Saturn’s north. Summer was coming. The Cassini spacecraft was there to see it [and passed] right over the storm for a closer look.
— from Storm chasing on Saturn by Dennis Overbye et al.
Let us create vessels and sails adjusted to the heavenly ether, and there will be plenty of people unafraid of the empty wastes. In the meantime, we shall prepare, for the brave sky-travellers, maps of the celestial bodies.
— from a letter by Johannes Kepler to Galileo Galileo written in 1610, cited by Ross Andersen.

Image: NASA

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