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> When the sun is completely blocked by the moon (which appeared about 3% larger than the sun during this particular eclipse), the total power delivered becomes

• dahart 9y ago
  Bummer that a nit that small would change your summary and overall emotional response, and prevent you from enjoying a great blot post, especially when the author pointed it out. "0%" is numerically accurate to at least 3 significant figures, isn't it? For me, it's really interesting that there's a discrepancy between the heat you feel and the light you see, and I love the writeup that is explaining the primary reason why -- because our perception of brightness is logarithmic, but our sensation of heat seems more linear in this case. The experience of being there and having it go cold before it got dark was startling, and I have to agree with the author, it's easy to see why this stuff caused so much emotional stir before science showed us how it all works. There's a much larger source of error, btw, in using a straight decibel scale as a proxy for brightness. (Also admitted & linked in the article.) It just doesn't matter, it's close enough, it's true, it's interesting, and it supports the narrative.
  • nayuki 9y ago
    The author's rushed approximation of "-infinity dB" is disingenuous, and discounts the efforts of people who handle low-level signals. For example, his claim makes it impossible to compare the ambient light level of an eclipse versus the light level from a full moon or new moon. For example, not knowing the noise floor will make it impossible to tell whether a 16-bit audio recording, or 20-bit, or 24-bit is the best choice. What is the "larger source of error" in using a decibel scale for brightness? Maybe the fact that human eyes are not perfectly logarithmic? But such a scale is very appropriate for calculating camera exposures.
    • dahart 9y ago
      Aww, come on, don't double-down, just let it be. If you want some benefit of the doubt, feel free to give some benefit of the doubt. We can nit pick each other to death, but that isn't going to be productive or fun at all. You can't take something out of context and claim that it's insulting people that he wasn't talking about. He wasn't discounting anyone. Yours is a bigger and more intentional error than his statement that totality is 0% energy. You're picking a fight instead of acknowledging that totality really is approximately 0% solar power for the purpose of figuring out how much heat you're going to feel on your arm during the eclipse, compared to before the eclipse. He admitted the noise floor is not really zero. He wasn't contradicting himself, he was clarifying for the sake of the nit pickers. You're using that against him instead of accepting that both of his statements can be true at the same time. He was never claiming absolute zero with infinite precision, that is completely clear from the article. He also wasn't asking what bit depth to use for audio recording. That would be weird, wouldn't it? Because he's talking about the sun's heat and not the sound it makes. He wasn't talking about photographing it either, or even measuring the heat precisely. He was showing why it gets cold before it gets apparently dark. You can do that in even less than 16 bits. Yes, human eyes are not perfectly logarithmic. Interesting that you don't care for the sake of camera exposures in the middle of a conversation about the sun and moon, where you just cited bit depths and people who handle low-level signals. The logarithmic approximation isn't particularly good, which the link in the article discusses in detail. Log is good enough for this article, but not for vision scientists. The logarithmic brightness approximation really truly breaks down when you look at the sun or the night sky, human vision does not give an approximately logarithmic response to either the sun or the night sky, not even close. Camera film and camera sensors also break down and begin to clamp at either end of a moderate log range that is narrower than human vision. Photographing the corona well is really hard due to the extreme dynamic range and the way that camera response stops being logarithmic at the ends.
      • ars 9y ago
        The person you are replying to is not wrong though. The author of the article is. Even during totality it's not as dark as night. It's around the illumination of just after sunset, and he could have definitely plotted that - it's not that hard to lookup how much there is then, he doesn't have to measure it himself.