c******n
发帖数: 16666 | |
H********g
发帖数: 43926 | |
H********g
发帖数: 43926 | 3 这个虽然不很相关，但是有点意思
Seeing stars and planets during the day was discovered thousands of years
ago. It was noticed first when digging deep water wells... from the bottom
of a deep well the diggers saw stars in the day time. A very "deep"
discovery. :) The principle was applied in the construction of some early
pyramids... One face of the pyramid had a vertical slot a few inches wide
splitting the whole structure back down to the observer positioned in a
chamber well back within and deep under the structure, able to watch the
apparent passage of stars and planets as the pyramid rotated under the sky
with the Earth's rotation, watching sky objects apparently pass across the
slot, which subtended about 90 vertical degrees of the sky... using candle
clocks or water clocks, the timing of these passages were recorded and
charts drawn (aligning a local curved rule featuring graduate marks like a
protractor against the distant slot for reference), so solar and lunar
positions tracked, planet movements tracked, stars mapped, etc. These were
basically astronomical observatories, cleverly aligned and designed, staffed
by shifts of sophisticated fellows with keen eyesight, allowing 24 hour sky
watching... a very long time ago. If you make a tube inner lined with black
felt, and make the tube long enough, you can try this yourself... it
basically absorbs almost all of the light that is not strictly parallel to
the longitudinal axis of the tube, which favors the light from distance
sources and reduces the light from scattered sources.
Reference https://www.physicsforums.com/threads/seeing-stars-during-the-
daytime.778550/ |
H********g
发帖数: 43926 | 4 哦，真的是微光夜视仪拍的么？因普乳癌西五。
【在 c******n 的大作中提到】
: http://i.imgur.com/jJ59S0P.gifv
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H********g
发帖数: 43926 | |
H********g
发帖数: 43926 | |
c******n
发帖数: 16666 | 7 你这个看着有点好玩啊+
【在 H********g 的大作中提到】
: 这个虽然不很相关，但是有点意思
: Seeing stars and planets during the day was discovered thousands of years
: ago. It was noticed first when digging deep water wells... from the bottom
: of a deep well the diggers saw stars in the day time. A very "deep"
: discovery. :) The principle was applied in the construction of some early
: pyramids... One face of the pyramid had a vertical slot a few inches wide
: splitting the whole structure back down to the observer positioned in a
: chamber well back within and deep under the structure, able to watch the
: apparent passage of stars and planets as the pyramid rotated under the sky
: with the Earth's rotation, watching sky objects apparently pass across the
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y****g
发帖数: 36950 | 8 这个不是纯光学的镜头吧？估计有芯片实时计算增强光线色彩
【在 c******n 的大作中提到】
: http://i.imgur.com/jJ59S0P.gifv
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H********g
发帖数: 43926 | 9 首先得够灵敏 信噪比要高
这个不是纯光学的镜头吧？估计有芯片实时计算增强光线色彩
【在 y****g 的大作中提到】
: 这个不是纯光学的镜头吧？估计有芯片实时计算增强光线色彩
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