The Terrestrial Space

The Greek mathematician Eratosthenes, towards 240 BC, was the first to evaluate the circumference of the terrestrial globe. He used the following method. Knowing that at noon the same day of the year the sun hit to the bottom of a well in Aswan, Egypt but produced a shade on an obelisk in Alexandria located to the north, he measured the distance between these two points. With the angle of the shade on the obelisk and the distance he then made an approximate evaluation of the terrestrial circumference, which was only within 15% of the real size.

Surface	510,900,000 km2
Equatorial diameter	12,746.32 km
Polar diameter	12,713.55 km
Equatorial circumference	40,075.15 km
Polar circumference	39,940.80 km
Rotation	The earth's movement around its polar axe (24 hours)
Revolution	The earth's movement around the sun (365 days and 1/4)
Earth's axis	23 degrees
Solstice	Summer: 21-22 June. Winter: 22-23 December.
Equinox	Spring: 20-21 March. Fall: 22-23 September.
Tropic of Cancer	Summer solstice, 23 degrees north.
Tropic of Capricorn	Winter solstice, 23 degrees south.
Meridian	Half circle having extremities at each of the poles.
Parallel	Circle produced on a parallel plan to the equator.
Latitude	Arc measured in degrees of a meridian according to the distance from the equator (0-90).
Longitude	Arc measured in degrees of a parallel between the place and the meridian of origin, Greenwich (0-180).
Co-ordinate	A longitude and latitude pair.