At night, someone is in a completely empty field. He sees absolutely nothing around him and there are no stars in the sky. He does not have a compass, or any other tools that can be used for navigation, and the only think he knows about the time is that it's before midnight. He's been there for less than a minute, but he already knows which way is north.

How did he know?

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    $\begingroup$ Can he see the moon? $\endgroup$ – user14478 Aug 22 '15 at 16:11
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    $\begingroup$ None of the answers there work, but a really interesting article on wikihow $\endgroup$ – Rohcana Aug 22 '15 at 18:25
  • $\begingroup$ "No stars in the sky"? This raises many issues, doesn't it? Can't he just not know which stars are which, like most people? $\endgroup$ – Roland Aug 22 '15 at 18:25

Even though this answer got accepted: This answer will not really work and it is not 100% correct. Thanks to Peter Taylor and Anachor for catching that. I would be interested if there is a better answer (there surely is).

I'm just gonna post my answer...

Becuase it's before midnight, the illuminated side of the moon faces west. (After midnight it's east). Now just face west and turn right - Then you face north.

  • $\begingroup$ You got it!​​​​ $\endgroup$ – Runemoro Aug 22 '15 at 16:18
  • $\begingroup$ This can only work if the midnight in the question is geographic/astronomical rather than political. The politics of time zones cause midday in some places to be wildly different to the time when the sun is at its zenith. $\endgroup$ – Peter Taylor Aug 22 '15 at 16:36
  • $\begingroup$ And it doesn't work half the time, because of lunar phases. Because he is there only a minute, the moon isn't visible for half the lunar cycle. $\endgroup$ – Rohcana Aug 22 '15 at 17:02
  • $\begingroup$ Yes, so the answer to "How did he know?" would be "The moon was low enough in the sky to make any differences between the timezone and astronomical timezone insignificant, and the moon was visible." $\endgroup$ – Runemoro Aug 23 '15 at 1:39
  • $\begingroup$ @Runemoro Then, you have no valid reason to deny chasley's answer. $\endgroup$ – Rohcana Aug 25 '15 at 10:21


He is on the ice field at the South pole. Any direction is North.

  • $\begingroup$ Sorry, that's not the right answer, but good try! $\endgroup$ – Runemoro Aug 22 '15 at 16:15
  • $\begingroup$ Yes, I didn't mean an ice field. $\endgroup$ – Runemoro Aug 22 '15 at 16:19
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    $\begingroup$ Actually, you are. There is no light pollution at the south pole so he should be able to see the stars. And there also is no "midnight", as there are no days. $\endgroup$ – Runemoro Aug 22 '15 at 16:27
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    $\begingroup$ @chaslyfromUK How does he know he is at the south/north pole? $\endgroup$ – Rohcana Aug 22 '15 at 17:05
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    $\begingroup$ It is also an assumption that you can see the moon. 1. It may not have risen or 2. If the stars are obscured so may the moon be, e.g. by heavy cloud. Incidentally does he know what hemisphere he is in? $\endgroup$ – chasly from UK Aug 22 '15 at 18:28

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