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Earth's mean radius #51

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kretz opened this Issue · 3 comments

2 participants

Martin Kretz James Cox
Martin Kretz

Hi there,

I recently moved from my own distance calculating code to geokit and found that the calculations differ on one point - the earth's mean radius.

Geokit uses a mean radius of 6376.77 km / 3963.19 mi

Wikipedia says 6371 km / 3959 mi (http://en.wikipedia.org/wiki/Earth_radius)

What do you base the current geokit numbers on? Would you be open to changing it?

Keep up the good work!
Martin

James Cox
Owner

I'm not sure where this data came from, but certainly open to change it. Can you find me another piece of evidence to back it up, and i'll change it? :)

thanks!

Martin Kretz

I found may different sources, stating a bit different numbers. The reason is probably that the earth is not perfectly spherical, and that people state the minimum, maximum and average. The one we are after should probably be the average, which is 6371 km.

More sources:
http://wiki.answers.com/Q/What_is_the_Earth's_radius

James Cox
Owner

OK. i will make this change in the release after the next one. I want to make sure that people are aware of this, as it's possibly going to break tests/expectations on that data.

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