How do we know that Mount Everest is exactly 8,848m high? When did we start to have data so accurate?
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Trigonometry , I leaned about that when I was in highschool sorry, I can’t remember the whole process
According to Bill Bryson, triangulation is “a popular technique based on the geometric fact that if you know the length of one side of a triangle and the angles of two corners, you can work out all its other dimensions without leaving your chair.”
You look at something from two different places, you measure the angle between the ground and the thing at each position, and you keep track of how far you have walked between those two places. You will then know enough to work out your distance from the thing.
Apparently, the greek astronomer Hipparchus of Nicaea used this method in 150 bc to work out the distance to the moon.
To figure out the altitude, you need to know your altitude during the measurement. Starting at sea level, you’re gonna have to chain triangles together as you make your way to mount everest. Altitude is just another distance, really.
That’s the most basic method, anyway. There are probably lots of shortcuts using the sun, air pressure or, you know, gps.
Well now we can use GPS satellites and other satellite mapping tools like synthetic aperture radar, but before that, we just used good old fashioned trigonometry. To measure the height of a mountain, surveyors used a method called triangulation. Observers examined the peak from several points. Knowing the distance from the points to the mountain, they were able to measure the angle from the summit to their observation points. Given the distance and the angle, they used trigonometry to calculate the mountain’s height relative to themselves. To calculate the mountain’s actual height above sea level, the observers themselves had to know their own elevation above sea level. They also had to take into account things like atmospheric refraction which can make distant objects appear higher or lower as light bends through the atmosphere. This method is remarkably accurate. In 1856, surveyors measured the peak of Mt. Everest to be 29,002 ft (8,840 m) above sea level from over 100 miles away. They were only off by 27 ft (8 m).
If you have the angle of the mountain and the length of his slope it’s simple math: length of the slope × sine of the angle = height of the mountain.
Its based on the level of the ocean otherwise referred to as “sea level”. Since sea level is always lower then the ground ( otherwise it would be under water) then the top is 0 ft. So Everest would be 8848 ft above sea level
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