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View Full Version : Questions Show: The Source of Atmospheres, the Vanishing Moon, and a Glow After Sunse



Fraser
2009-May-19, 09:30 PM
How do planets get their atmospheres? What would happen to the Earth if the Moon just disappeared? And what’s that strange glow we see after sunset? If you've got a question for the Astronomy Cast team, please email it in to info@astronomycast.com and we'll try to tackle it for a future show. Please include your location and a way to pronounce your name.http://feeds2.feedburner.com/~r/astronomycast/~4/KFtGSQQJXkU

More... (http://feedproxy.google.com/~r/astronomycast/~3/KFtGSQQJXkU/)

tarashnat
2009-May-28, 10:42 PM
Pamela & Fraser:

You guys totally forgot about noctilucent clouds as a possible source of light after sunset.

Taras

robross
2009-May-29, 08:41 AM
Pamela & Fraser:

You guys totally forgot about noctilucent clouds as a possible source of light after sunset.

Taras

They didn't mention this specifically, but Pamela did say there was an effect where dust in orbit could reflect sunlight back into the atmosphere. But note : both of these require the setting sun slightly below the horizon, which sets in the *West*. The questioner specifically said he saw this in the *East*, so I think Pamela's hypothesis that it was the lights from a city is probably accurate. At any rate, this could not have been noctilucent clouds, since it's in the wrong part of the sky.

Rob

tarashnat
2009-Jun-04, 10:49 PM
They didn't mention this specifically, but Pamela did say there was an effect where dust in orbit could reflect sunlight back into the atmosphere. But note : both of these require the setting sun slightly below the horizon, which sets in the *West*. The questioner specifically said he saw this in the *East*, so I think Pamela's hypothesis that it was the lights from a city is probably accurate. At any rate, this could not have been noctilucent clouds, since it's in the wrong part of the sky.

Rob

http://spaceweather.com/archive.php?view=1&day=04&month=06&year=2009

"Last night, we had our first really beautiful display of noctilucent clouds this season. They have really taken off now!" reports John C. McConnell of Maghaberry, Northern Ireland, who took the picture below using a Canon 400D. "The display started just after twilight ended and lasted until 03:00 o'clock in the morning."

If they are only visible in the West after twilight, then how could they last until 3 AM? I'm sure the geometry would allow them to be visible in the Eastern sky after twilight, though probably not at the horizon.