November 22, 2012

Watching Time Fly

ivideo by NASA/Goddard Space Flight Center Scientific Visualization Studio

Do you have a Moon phase calendar yet for 2013? NASA's Goddard Space Flight Center has just released an animated one with a variety of additional types of information. At Goddard's website you will find 4 different versions of the video that the above image comes from. I like the second version because it has wonderful music by Mozart (if you prefer a more modern and spacey score Phil Plait has one). Using LRO altimetry data and shadow-casting algorithms the Moon is shown with the correct phase, libration and shadows for every hour of 2013's 365 days. Images from Clementine apparently were used for high Sun albedos - notice that Cassini's Bright Spot is suitably saturated for a short time. The smaller globe in the bull's eye at bottom left mimics the librational tilts and phases of the big image with a blue dot marking where on the Moon's surface that the Earth would be directly overhead, and the yellow dot does the same for the Sun - notice how it circles the entire Moon. At right center a dot on a line tracks the Moon's changing distance from the Earth due to its elliptical orbit. While this is a fun and informative animation I have some suggestions. Add a speed control - it changes so fast that I can't look at the date and time and the illuminated phase, and the top left orrey of the Moon circling the Earth makes me dizzy with the chronologically correct rapid rotation of Earth. Finally, the most important piece of the data block at bottom right is the date and time - that line needs to be larger and perhaps in a distinctive color to aid correlation with the animation. With each 24 hrs taking about 1.5 seconds everything is just too fast.

Chuck Wood
Note: I can't help but remember that 49 years ago President Kennedy - the man who decided the US should go to the Moon - was murdered in Dallas. I remember that day very well.

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