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VENUS & THE MOON: The crescent moon is approaching Venus and tomorrow night, Sunday, Dec. 4th, they will appear side by side in the sunset sky. Look south for a beautiful view: sky map.
BIG SUNSPOT: Sunspot 826 is still growing. Barely visible only a few days ago, it is now a behemoth as wide as the planet Jupiter. If you have a safely-filtered solar telescope, take a look at this 'spot. It is changing by the hour:
Above: A 3-day SOHO movie of sunspot 826, Nov. 29th - Dec. 3rd.
The magnetic field of a fast-changing sunspot like 826 can easily become unstable and explode. NOAA forecasters estimate a 25% chance of X-class solar flares during the next 24 hours.
GREEN PATCHES: The Sun is a G-type star, which means its surface temperature is about 6000°C and its color is yellow. So where does the green come from? On Nov. 26th, when "Mendonça Jr." of São Luis do Purunã, Brazil, photographed the sunset, he noticed some green patches around the edge of our star: (continued below)
Atmospheric optics expert Les Cowley has the answer:
"Low cost binoculars and telescopes put colored fringes around stars or tree branches silhouetted against the sky. Their imperfect lenses focus blue and red light differently. Earth's atmosphere is also an imperfect lens and it rims the top of the setting sun with green."
"Why green?" he asks. "It would be blue but the air and dust have scattered that color away. The green rim is too narrow to see by eye. People can, however, see a green flash, which needs needs a mirage to magnify the color separation."