This blog provides commentary on interesting geological events occurring around the world in the context of my own work. This work is, broadly, geological fluid dynamics. The events that I highlight here are those that resonate with my professional life and ideas, and my goal is to interpret them in the context of ideas I've developed in my research. The blog does not represent any particular research agenda. It is written on a personal basis and does not seek to represent the University of Illinois, where I am a professor of geology and physics. Enjoy Geology in Motion! I would be glad to be alerted to geologic events of interest to post here! I hope that this blog can provide current event materials that will make geology come alive.

Banner image is by Ludie Cochrane..

Susan Kieffer can be contacted at s1kieffer at gmail.com

Wednesday, October 14, 2015

Jupiter's Red Spot is shrinking!!

Comparison of Jupiter's Red Spot
with Earth. Image from
After a 2-month hiatus, I'm going to work my way back into regular posting. But will start in a very lazy way by referring you to a really cool video here, a new NASA time-lapse portrait of Jupiter!
      Jupiter is the largest planet in the Solar System with an equatorial radius of about 11 times that of the Earth, and about 1/10 of the radius of the sun.  It is a gassy planet, and it's upper atmosphere consists of about 75% hydrogen and 24% helium by mass, with a trace of methane, water, ammonia, .... It's atmosphere spans 5,000 km (3100 miles) in altitude, though since Jupiter has no solid surface of rocks like the earth, the base is rather arbitrarily defined as the point where atmospheric pressure is about 10 times the surface pressure on Earth.
     The Great Red Spot is a vortex, an anticyclonic (rotating counterclockwise) storm that is known to have existed since 1831, and possibly since 1665 where it was reported in the very first volume of the Philosophical Transactions (of England)  that a small spot in the biggest of the three observed belts had been spotted with a twelve foot telescope. The Great Red Spot is about three times the diameter of the earth as shown in the image to the left. It "sticks out" above the surrounding cloud tops by 8 kilometers.
      For a technical paper on the topic, see Asay-Davis et al., Icarus, 203(1), pp. 164-188, September 2009, in which they show that "between 1996 and 2006, the area circumscribed by the high-speed collar of the Great Red Spot (GRS) shrunk by 15%...."

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