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What is the Darkest Hour of the Night?
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Eugene Shubert (or somebody else of the same name) wrote thusly in message
: What is the darkest hour of the night? Eugene Shubert http://www.everythingimportant.org Isn't it supposed to be just before dawn? Sounds unlikely on scientific grounds though, so I'd say it's around the (real local) midnight. -- Paul Townsend Pair them off into threes Interchange the alphabetic letter groups to reply |
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Prai Jei wrote in message ...
Eugene Shubert (or somebody else of the same name) wrote thusly in message : What is the darkest hour of the night? Eugene Shubert http://www.everythingimportant.org Isn't it supposed to be just before dawn? Yes. Sounds unlikely on scientific grounds though, so I'd say it's around the (real local) midnight. Googling the phrase "It's always darkest before dawn" turn up 1750 hits. An astronomer should know when it really is the darkest hour of the night. I'm looking for a confident, scientifically measured answer, not a reasonable guess. Eugene Shubert http://www.everythingimportant.org |
#6
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"Mr. 4X" wrote in message ...
(Eugene Shubert) wrote in message om: What is the darkest hour of the night? That depends on a lot of things. There is almost no direct sunlight 2-3 hours after sunset, Isn't there a measurable amount of sunlight that's scattered by the atmosphere, reaching further into the night than a mere 2-3 hours of earth rotation? When a sizable part of the earth's surface and atmosphere is heated up during the day, doesn't a measurable fraction of that heated material reradiate energy in the visible spectrum? To keep the calculations simple, let's ignore artificial lighting but factor in the reflected light of the Moon if you know how to do that. Eugene Shubert http://www.everythingimportant.org |
#7
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"Eugene Shubert" wrote in message om... "Mr. 4X" wrote in message ... (Eugene Shubert) wrote in message om: What is the darkest hour of the night? That depends on a lot of things. There is almost no direct sunlight 2-3 hours after sunset, Isn't there a measurable amount of sunlight that's scattered by the atmosphere, reaching further into the night than a mere 2-3 hours of earth rotation? Zodiacal light. When a sizable part of the earth's surface and atmosphere is heated up during the day, doesn't a measurable fraction of that heated material reradiate energy in the visible spectrum? To keep the calculations simple, let's ignore artificial lighting but factor in the reflected light of the Moon if you know how to do that. It will be darkest at local midnight in midwinter when the Moon is new and Venus is below the horizon. I wonder how often that combination occurs (if ever). George |
#8
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"Eugene Shubert" wrote in message om... What is the darkest hour of the night? It doesn't have one. "Will there really be a morning? Is there such a thing as day? Could I see it from the mountains If I were as tall as they? Has it feet like water-lilies? Has it feathers like a bird? Is it brought from famous countries Of which I have never heard? Oh, some scholar! Oh, some sailor! Oh, some wise man from the skies! Please to tell a little pilgrim Where the place called morning lies!" By E Dickinson s Eugene Shubert http://www.everythingimportant.org |
#9
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"George Dishman" wrote in message ...
"Eugene Shubert" wrote in message om... "Mr. 4X" wrote in message ... (Eugene Shubert) wrote in message om: What is the darkest hour of the night? That depends on a lot of things. There is almost no direct sunlight 2-3 hours after sunset, Isn't there a measurable amount of sunlight that's scattered by the atmosphere, reaching further into the night than a mere 2-3 hours of earth rotation? Zodiacal light. I thought that the zodiacal light was scattered off of Solar System dust in the plane of the ecliptic, rather than Earth's atmosphere? When a sizable part of the earth's surface and atmosphere is heated up during the day, doesn't a measurable fraction of that heated material reradiate energy in the visible spectrum? To keep the calculations simple, let's ignore artificial lighting but factor in the reflected light of the Moon if you know how to do that. It will be darkest at local midnight in midwinter when the Moon is new and Venus is below the horizon. I wonder how often that combination occurs (if ever). How can Venus *not* be below the horizon at local midnight? Venus reaches a maximum elongation of about 48 degrees relative to the Sun. If I've done the math correctly, Venus should always be below the horizon by 3 hours and 12 minutes after sunset. George -- Rainforest laid low. "Wake up and smell the ozone," Says man with chainsaw. John J. Ladasky Jr., Ph.D. |
#10
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(Eugene Shubert) wrote in
message om: "Mr. 4X" wrote in message ... (Eugene Shubert) wrote in message om: What is the darkest hour of the night? That depends on a lot of things. There is almost no direct sunlight 2-3 hours after sunset, Isn't there a measurable amount of sunlight that's scattered by the atmosphere, reaching further into the night than a mere 2-3 hours of earth rotation? I think that scattering probably decreases as you get closer to the Equator (same angular distance = more linear distance). When a sizable part of the earth's surface and atmosphere is heated up during the day, doesn't a measurable fraction of that heated material reradiate energy in the visible spectrum? NO. Thermal radiation has no (or at least no significant) visible component under 300 C or something like that. To keep the calculations simple, let's ignore artificial lighting but factor in the reflected light of the Moon if you know how to do that. Eugene Shubert http://www.everythingimportant.org |
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