As the resident astronomy dropout who's solved these problems more often than you've had hot callgirls, let me say that this problem is more complex than it first appears.

First, recall that the earth is (nearly) spherical. Spherical trigonometry is required, as others have pointed out, which is not always the simplest of math. Amongst other things, it takes into account that one degree east-west is a lot greater distance near the equator than near the pole.

However, the earth is not exactly a sphere. It is slightly flatted at the poles; technically, the shape is an 'oblate spheroid', kind of like what you get when you sit on a basketball or soccer ball for a while. And what's more, the earth really isn't an oblate spheroid, either. There is something known as The South Atlantic Anomoly, where the earth's crust bulges a bit, whether in or out I can't recall.

This brings up another issue, that while the earth is mostly at the same distance from the center, it isn't exactly all at the same distance. In the Himalayas you are dealing with a larger distance from the center, and thus 5 miles takes less of an angular distance than, say, next to The Dead Sea.

Normally, these differences are small, but the distance you are 'moving' is also small, only five miles, so those small differences can be a significant percent of what you calculate.

Hope this helps.

--
tbone1
Ain't enough 'O's in 'stoopid' to describe that guy.
- Dave "the King" Wilson

In reply to Re: How do I compute the longitude and latitude of a point at a certain distance? by tbone1
in thread How do I compute the longitude and latitude of a point at a certain distance? by themaetrix

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