how does a sextant work?
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It’s like a protractor…**FOR THE STARS!**
Seriously though, that’s what it is. It helps you sight two different far away objects (typically 2 stars, or the horizon and a particular star), and then has little gradations so you can measure how many degrees apart they are from where you’re standing.
The main use of a sextant is to figure out your latitude (that is, how far you are from the equator). In the northern hemisphere, there is a star that’s almost exactly at the north pole. The angle between that star and the horizon gives you how far you are from the equator. In the southern hemisphere, there is unfortunately no convenient star, but you can figure it out by taking the intersection of a couple of lines made by a couple constellations. A similar method is to measure the height of the sun at noon (90 minus this number is your latitude), though obviously it’s somewhat dangerous to look directly at the sun without a filter.
Sextants may also be used more generally to measure distance between any pair of celestial objects – planets, stars, the moon, etc., which together with complex tables can be used to figure out other stuff like the time and date, or your approximate longitude.
They can also be used to figure out your distance from shore if you find the angular distance between two objects (like a pair of lighthouses, or a lighthouse and a church spire) whose straight-line distance you know.
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