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Orbital night city light visibility
How visible are the lights of cities from orbit at night? Is it something
you'd see with the naked eye without really trying? Same with lightning, can you see the clouds light up easily? Thanks, David |
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Orbital night city light visibility
On May 11, 2:37 am, David Findlay wrote:
How visible are the lights of cities from orbit at night? Is it something you'd see with the naked eye without really trying? Same with lightning, can you see the clouds light up easily? Thanks, David I remember one of the early astronauts (from Mercury, IIRC) describing looking down on Africa at night and seeing campfires. One of the rules of thumb from photographic lighting is that, for extended objects (not point light sources), the observed surface brightness is independent of distance. That's because both the observed angular area and the total brightness vary with the inverse square of distance, so the brightness per unit angular area stays constant. If that doesn't make sense, here's a more relevant illustration of the point: If you've ever flown in an airliner at night, you'll notice that cities near the horizon appear about as bright as cities directly below you, assuming they're relatively equally densely populated and equally lit. And cities near the horizon from a 35,000 ft airliner are at close to the same distance as cities directly below an orbiting spacecraft. I've never been in an orbiting spacecraft, but I'd expect that, once you're on the dark side of Earth, if your interior lights are suitably dimmed and your eyes are properly dark-adapted, it should be easy to pick out cities at night. |
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Orbital night city light visibility
On May 11, 12:05 pm, wrote:
On May 11, 2:37 am, David Findlay wrote: How visible are the lights of cities from orbit at night? Is it something you'd see with the naked eye without really trying? Same with lightning, can you see the clouds light up easily? Thanks, David I remember one of the early astronauts (from Mercury, IIRC) describing looking down on Africa at night and seeing campfires. Found a further reference: http://science.nasa.gov/headlines/y2...noseprints.htm |
#4
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Orbital night city light visibility
wrote in message ups.com... On May 11, 12:05 pm, wrote: On May 11, 2:37 am, David Findlay wrote: How visible are the lights of cities from orbit at night? Is it something you'd see with the naked eye without really trying? Same with lightning, can you see the clouds light up easily? Thanks, David I remember one of the early astronauts (from Mercury, IIRC) describing looking down on Africa at night and seeing campfires. Found a further reference: http://science.nasa.gov/headlines/y2...noseprints.htm Way back in 62 the city of Perth , Australia turned their lights on for John Glenn on his orbital flight. He was able to see them clearly. They did it again for his shuttle trip. Perth was not a huge city in 62, terry |
#5
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Orbital night city light visibility
"David Findlay" wrote in message ... How visible are the lights of cities from orbit at night? Is it something you'd see with the naked eye without really trying? Same with lightning, can you see the clouds light up easily? Thanks, David I am not sure about city lights, but I have talked to astronauts that have told me lightening/thunderstorms are VERY visible from orbit. Michael Collins also mentions this in his book. Danny Deger |
#6
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Orbital night city light visibility
On May 11, 2:37 am, David Findlay wrote:
How visible are the lights of cities from orbit at night? Is it something you'd see with the naked eye without really trying? Same with lightning, can you see the clouds light up easily? Thanks, There's that composite photo of the USA at night, taken with DOD satellite cameras (the weather one, IIRC). One of the filenames you may find this under is "nightlights-081503-0103z.jpg" (although my copy is just the NE states). I think there is also some post-Katrina pix showing how the Gulf Coast stayed in the dark. True, satellite cameras often have better resolution than the human eye, but they are also often farther out, so I think there's a lot of opportunity for spotting cities, and maybe towns. /dps |
#7
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Orbital night city light visibility
"snidely" wrote in message ups.com... On May 11, 2:37 am, David Findlay wrote: How visible are the lights of cities from orbit at night? Is it something you'd see with the naked eye without really trying? Same with lightning, can you see the clouds light up easily? Thanks, There's that composite photo of the USA at night, taken with DOD satellite cameras (the weather one, IIRC). One of the filenames you may find this under is "nightlights-081503-0103z.jpg" (although my copy is just the NE states). I think there is also some post-Katrina pix showing how the Gulf Coast stayed in the dark. True, satellite cameras often have better resolution than the human eye, but they are also often farther out, so I think there's a lot of opportunity for spotting cities, and maybe towns. /dps I've seen a poster of the whole world in night time clear views from orbit. It's amazing, because you can see the city lights all over the heavily populated and developed areas. The most interesting point I saw was the difference in North and South Korea. You can make out the 38th parallel from the sudden absence of lights. Mike Ross |
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