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Concorde flew to an altitude of 60,000 ft (18.3 km) where stars should be visible at noon, aren't they? This question asks on how high stars become visible, and it is said Blackbird pilots could see them at 80,000 ft. Concorde flew at the Armstrong line when highest, above more than 90% of the atmosphere's mass. Are there reports of passengers and pilots on Concorde seeing stars (other than the Sun) when at peak altitude? Also, did the Sun appear whiter due to the thinner atmosphere?

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    $\begingroup$ You can see Sirius from sea level. Climbing to 18 km doesn't change anything, still only Sirius. "The daylight visibility of stars has been investigated for an observer altitude of 100 000 ft, using published visual threshold data and calculated sky luminance. Venus, Jupiter, and Sirius, plus Mars at its brighter phases, can be detected with the naked eye", source. Sirius has a magnitude of -1.46 at sea level. At night an eye can see down to +6 only. Someone may build an answer starting with these elements. $\endgroup$
    – mins
    Sep 19, 2020 at 2:04
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    $\begingroup$ @Someone -- there's nothing wrong with referring to the Concorde as "the Concorde", even if the accepted usage (for some weird reason, no other plane is treated this way, and this has been the subject of an ASE question aviation.stackexchange.com/q/57085/34686) is simply "Concorde". IMHO that was a totally superfluous edit (version #3). $\endgroup$ Feb 28, 2023 at 17:14
  • $\begingroup$ @Someone-- actually, I forgot that you were the one who bountied that question not so long ago. Thanks, that was nice-- but I still do feel the recent edits are superfluous. $\endgroup$ Feb 28, 2023 at 17:46
  • $\begingroup$ @quietflyer okay, I won't change it in old questions anymore. If I'm editing one anyway for another reason, should I change it then? $\endgroup$
    – Someone
    Feb 28, 2023 at 18:30
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    $\begingroup$ Your call-- I'd prefer you not on my own question, but I only asked one question about the Concorde, so prob won't be an issue. Thanks for replying. $\endgroup$ Feb 28, 2023 at 18:46

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Yes, in at least one exceptional circumstance. The book Racing the Moon’s Shadow with Concorde 001 describes a 1973 scientific flight that remained in the moon's umbra for more than an hour, in daytime. As stars are quite visible from the ground during a solar eclipse's totality, they would have been even more visible from a 17 km altitude.

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    $\begingroup$ I don't think the question was asking about a solar eclipse! Even though it's technically "in daytime", the question is clearly about normal daylight. $\endgroup$
    – Bianfable
    Sep 14, 2020 at 16:16
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    $\begingroup$ I don't think so, either! But I couldn't resist, that flight was just so cool. $\endgroup$ Sep 14, 2020 at 16:43
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    $\begingroup$ @CamilleGoudeseune Sorry but during a total eclipse you can see them even from the sea level as you say yourself. :-) $\endgroup$
    – Giovanni
    Sep 14, 2020 at 16:48
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This page has some images of the view from the Concorde. On one image two stars can be seen. So obviously one could see some.

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    $\begingroup$ Can't tell which photo you're referring to as having stars in it. Also, FWIW, even at midnight photos that size have a hard time depicting individual stars - they're just so tiny & pretty dim. Doesn't mean that stars are, or aren't, there for the eye to see, just that they're hard to capture in small photos with nearer (and much brighter) objects in view & in focus. $\endgroup$
    – Ralph J
    May 11, 2021 at 14:59
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    $\begingroup$ Is this answerer a duplicate account of the questioner's? $\endgroup$ May 11, 2021 at 15:32
  • $\begingroup$ @RalphJ On the image on which you only see the horizon, no Concorde window and no Concorde wing, only the Earth from cruise altitude. You can see a star on the upper left and another on the upper right of the dark sky. Or at least I assume it are stars. $\endgroup$
    – Giovanni
    May 11, 2021 at 16:01
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    $\begingroup$ meta.stackexchange.com/help/merging-accounts fyi $\endgroup$ May 11, 2021 at 17:36
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    $\begingroup$ Those specks look both too large and way too bright to be stars. They're basically as bright as the clouds in daylight, and stars aren't nearly as bright as that. Try taking a picture of the night sky on a clear, dark night with your phone's camera... you might get individual stars, but probably not. Now try it with something moderately bright (like that cloud layer) in part of the photo... the camera won't see stars at all. I'd strongly suspect those specks are either on the camera lens or the aircraft window. $\endgroup$
    – Ralph J
    May 11, 2021 at 21:27

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