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Comment by __alexs | Hacker News Reader

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__alexs·

Similarly you can estimate the time before sunset using your body.

Hold out your arm and see how many fingers fit between the bottom of the sun and the horizon.

Each finger is about 15 minutes.

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I was taught 1 fist == 1 hour. Then you'd stack fist over fist to determine how many hours left of sunlight. I just tried using fingers and that also seems pretty easy, and likely to result in a similar estimate.

As long as you have four fingers on each hand, a fist is about the same height as four fingers, so I think the math checks out.

Is there a measure of when the sun is behind the “horizon” (tall mountains) so it’s not directly visible but is still producing a lot of daylight? Maybe length of dusk or something

A bit longer if you're within a polar circle.

I doubt the method does give a good approximation even at about 60° north in July, although I did not verify by how much. I live near 49° north and recently travelled to Scandinavia. While my intuition at home is pretty accurate, my idea of how long it takes for the sun to set so far north in the evening was completely off the mark at first. To calibrate it, I changed my mental model of the sunset to a double-flat angle and estimated how long it might take the sun to (virtually) cover the longer resulting distance.

...how do you do this without looking at the sun?

I would think that a single quick glance in the general direction of the sun won't do much harm

You don't, but it won't work until the answer is three fists or less, and glancing at the sun in the evening isn't going to hurt you for the time it takes to put your fist/fingers next to it.

cover the sun with your left hand and position it so the bottom of that hand is just covering the bottom of the sun. then start measuring with your other hand, from the sun to the horizon

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