1. Geographic position is an exact area position compared to a different surrounding region.
2. Geographically, Indonesia was placed between two continents which are Asia and Australia and two oceans which are the Pacific Ocean and the Indian Ocean.
3. Indonesia’s northern territory limits are 6o 08′ parallel north through Weh Island, southern territory limits are 11o 15′ south latitude through Rote Island, western territory limits are 95o 45 ‘ longitude east through Beureuh Island and the limits of the eastern territory are 141o 05’ longitude east across the Fly River and Merauke River.
4. Indonesia had a longitude leg of 46o (141o BT – 99o Lon East) and a latitude leg of 17o (6o LU + 11o South Lat).
5. Astronomical positions is a position of a region in the ground service that is based on longitude and latitude coordinates. This astronomical position is known as the absolute position because it is definite.
6. Equator line [0o ] it is a virtual line that crosses from west to east or from east to west parallel with the orbital lines of the sun 0o at the equator that makes the separation region on earth become southern territory and northern territory.
7. Meridian Line [0o ] it is a virtual line that runs vertically from the north pole to the south pole through the Greenwich observatory in England that makes the region of separation become the western region and the eastern region. The meridian line, also known as the GMT line, stands for Greenwich Mean Time.
8. The line of latitude is a virtual line that runs horizontally from west to east, parallel to the equator.
9. The line of longitude is a virtual line that runs vertically from north to south parallel to the meridian line.
10. Coordinate point is a crossing point or a meeting point of longitude and latitude.
11. Astronomically, Indonesia’s position is 6o Par North – 11o Southern Lat and 95o Lon East – 141o Lon West.
12. Due to its astronomical position, Indonesia resides in a tropical zone. Indonesia has three different time zones. It happens because each circular rotation of the earth changes 15° (360°/24 hours) from the meridian line, which causes a time difference of 1 hour.
13. Western Indonesia Time Zone [WIB] at the edge of 105o Lon East it covers Sumatera, Jawa, Madura, Central Kalimantan and West Kalimantan. Central Indonesia Time Zone [WITA] at the edge of 120o Lon East it covers Bali, West Nusa Tenggara, East Nusa Tenggara and Sulawesi. Northern Indonesia Time Zone [WIT] at the edge of 135o Lon East it covers Maluku and Papua.
14. From April to October, around September 22, the relative position of the sun is in the tropics of the constellation of Capricorn. [Tropica Capricorn] against the territory of the South of the Earth (23.5o Lat. South), so in those periods the sun moves from the Tropic of Capricorn to the equator. This condition contributes to Australia’s climate. Monsoon breeze from Asia to Australia across the Indian Ocean. And Indonesia has rainy season during the time.
15. From April to October, around June 21, the position of the sun is relatively in the tropics of the constellation of Cancer. [Tropica Cancer] against the territory of the North of the Earth (23.5o Par. North), so in that period the sun moves from the Tropic of Cancer to the equator. This condition contributes to the climate of Asia and Australia against the cold season and the breeze of the wind in Asia. Monsoon weather was a breeze from Australia to Asia through poor water vapor over the ocean. And Indonesia has a dry season during the time.
16. Between those seasons, from September to October and from April to May, the wind direction was unpredictable and had an impact on weather conditions in Indonesia. Those conditions known as transition period [pancaroba].
Krisnadi N. Wahyudi