6 Km
1000 Km
3600 Km
36000 Km
Isaac Newton
Eratosthenes
Copernicus
Galileo
High latitudes
Low latitudes
Mid latitudes
Sub tropics
The earth’s orbit
The celestial sphere
The elliptic path
The ecliptic plane
Poles
Tropic of Cancer
Tropic of Capricorn
Equator
Triangular
Circular
Hexagonal
Rectangular
0°C
17°C
23°C
31°C
March 21
June 21
September 23
December 21
Thermal radiation
Solar radiation
Solar heat
Insolation
25km/sec.
31km/sec.
39.5km/sec.
9.72km/sec.