What is the diameter of the earth, and how many decimal places are relevant in all these latitude/longitude pairs that I’m quoting on web pages?
Its been bugging me for a while, finally dug around and had a quick look. 40,075.16km at the equator, 40,008km through the poles. Hmm, that means that one degree is approximately 111km, one decimal point is 11km, two decimal points is 1.1km and more than that is pretty much irrelevant… at least until I get my hands on a GPS unit.
From the MaNIS Georeferencing guidlines:
**Uncertainty based on coordinate precision**
**using the WGS84 reference ellipsoid**
| Precision | 0° Latitude | 30° Latitude | 60° Latitude | 85° Latitude |
|---|---|---|---|---|
| 1.0° | 156904 m | 146962 m | 124605 m | 112109 m |
| 0.1° | 15691 m | 14697 m | 12461 m | 11211 m |
| 0.01° | 1570 m | 1470 m | 1247 m | 1122m |
| 0.001° | 157 m | 147 m | 125 m | 113 m |
| 0.0001° | 16 m | 15 m | 13 m | 12 m |
| 0.00001° | 2 m | 2 m | 2 m | 2 m |
| 1.0 minutes | 2615 m | 2450 m | 2077 m | 1869 m |
| 0.1 minutes | 262 m | 245 m | 208 m | 187 m |
| 0.01 minutes | 27 m | 25 m | 21 m | 19 m |
| 0.001 minutes | 3 m | 3 m | 3 m | 2 m |
| 1.0 seconds | 44 m | 41 m | 35 m | 32 m |
| 0.1 seconds | 5 m | 5 m | 4 m | 4 m |
| 0.01 seconds | 1 m | 1 m | 1 m | 1 m |
- Home:
Richmond(-37.833,145.000)
- Work:
Clayton North(-37.916,145.133)
