Friday, June 8, 2012
The Sun and Venus From Mauna Loa
Many of us watched the Venus transit on a live feed from the NOAA observatory at 11,000 feet on Hawaii's Mauna Loa volcano.Light winds pushing the telescopes caused the images to shimmer.Venus was a big black dot much larger than the sunspots also visible on the sun's surface.Sunspots are magnetic storms a few hundred degrees cooler than the surface of the sun,hence darker in appearance.They have a black umbra,or center,and a gray penumbra,or border.Giant convection cells of heat rise from beneath the solar disc;they are from hydrogen bubbling up from below the surface,causing lighter and hotter regions on the sun.We are near a solar maximum,when there are a lot of sunspots and other activity on the sun.It is the peak of a solar cycle.This was the longest period of time-45 minutes just before sunset-that I have ever observed the sun.It's so liquid and alive:an aspect of the sun we aren't normally aware of.The astronomer Galileo first discovered this;but,in his ignorance of the danger,paid with his priceless eyesight,his retinas damaged by the intensity of the solar rays.Now Venus moved along the sun's rim;but the sun itself,looking blue,red and yellow in the telescopes' filters,had become my fascination.
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