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I know it's a bit late for the UK eclipse, but for future reference: Welders goggles do not cut out the same frequency of light that Mylar/Black Polymer eclipse glases do. Arc welding glass #14 is much darker than brazing welders glass but there is no guarantee that they will block the Sun's ultra-violet and infrared rays. The problem is there are no ...


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Wasn't it pretty obvious to a careful astrologer a thousand years ago, that the Moon does not have a circular orbit and does not describe epi-cycles? The ancient Greek model of the motion of planetary bodies remained unchallenged for almost two millennia, so obviously not. Hipparchus' model did a fairly good job dealing with the elliptical motion of ...


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The core of the question has already been answered, but it's still interesting to illustrate just how difficult it is to make a naked eye observations of a the extremely bright nearby galaxy M81. The astronomer Brian Skiff gives an account of his successful naked eye observation of this galaxy here. Now, galaxies of a given brightness are more difficult to ...


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Can a Human See a Single Photon? The human eye is very sensitive but can we see a single photon? The answer is that the sensors in the retinacanrespond to a single photon. However, neural filters only allow a signal to pass to the brain to trigger a conscious response when at least about five to nine arrive within less than 100 ms. If we could ...


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The format of the files seems to be described in this file, the content of which I've included below. The annual files (1939-1993) contain the green coronal emission line 530.3 nm observations. The coronal intensities are given in millionths of intensity of the solar disk (coronal units) and converted to the photometrical scale of Lomnicky Stit Station at ...



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