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. 40,075.16 ㎞ at the equator, 40,008 ㎞ through the poles. Hmm, that means that one degree is approximately 111 ㎞, one decimal point is 11 ㎞, two decimal points is 1.1 ㎞ 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)
