NATARAJAES-01
Rotating Earth and coordinate systems
Learning outcomes & permitted supports
- Identify axes, poles, equator, meridians and parallels, and read any position as latitude and longitude.
- Distinguish great circles from small circles and say why the difference matters for distance.
- Compute DLat and DLong (shortest way, date-line safe) and convert longitude to miles through latitude.
Supports in this lab: interactive sphere, engine-computed differences and distances. No tables needed.
Glossary: latitude · longitude · DLat/DLong · great circle · small circle · nautical mile · declination
The sphere itself
Coordinates & differences (engine)
| A (vessel) | 18° 56.4′ N 072° 49.8′ E |
|---|---|
| B (destination) | 01° 21.0′ N 103° 49.2′ E |
| DLat A→B | 17° 35.4′ S |
| DLong A→B (shortest) | 030° 59.4′ E |
| Great-circle distance | 2105.3 nm |
| 1′ of latitude | 1.0 nm (everywhere) |
| 1° of longitude at 18° 56.4′ N | 56.8 nm |
Slide A toward the pole and watch one fact do all the work: a minute of latitude is always a mile, but a degree of longitude shrinks with cos(lat) — longitude is an angle, never a distance. DLong is computed the shortest way round; drag B across the date line and watch it stay small while the raw difference would jump to 350°+.