Latitude and Longitude are how your site location is defined on the surface of the earth
Latitude is used to express how far north or south you are, relative to the equator. If you are on the equator your latitude is zero. If you are near the north pole your latitude is nearly 90 degrees north. If you are near the south pole your latitude is almost 90 degrees south.
Conventionally latitude is expressed as degrees north or south. For inputting to the satellite dish pointing calculator, south latitude figures need to be input as negative numbers.
Note that from small regions around the north or south poles you cannot see geostationary satellites at all. The geostationary satellites are below the horizon and directly above the equator, in a circle all around.
Longitude shows your location in an east-west direction, relative to the Greenwich meridian. Places to the east of Greenwich (such as Middle East, India and Japan) have longitude angles up to 180 degrees east. Places to the west of Greenwich (such as the Atlantic and North and South America) have angles up to 180 deg west. For inputting to the satellite dish pointing calculator, longitude west figures need to be input as negative numbers.
|Geostationary satellites are located in orbit directly above the equator and stay in the same place in the sky since they go around the earth at the same angular speed as that of the earth as it rotates. Satellite locations may thus be defined by longitude only. The use of east and west longitudes is popular for public use since the numbers are smaller. Use of degrees east only (0 to +360 deg, going east from Greenwich) however is my preference since the satellites go around this way and it makes sense for the numbers to keep increasing if the satellite moves forwards. Trying to do orbit calculations is bad enough without having numbers that keep switching forwards and backwards. Many satellite operators also use the 0 to +360 deg method, but may additionally provide the "deg west" notation for some output publications.|
Maps and GPS receivers show latitude and longitude angles. Maps usually show bold lines marked in degrees (whole numbers) plus possibly intermediate lines marked 15, 30, 45 minutes or 10, 20, 30, 40, 50 minutes. GPS receivers typically show degrees plus minutes and decimal fractions of a minute. e.g. 45 : 23.1234 You can normally alter the display options on a GPS using the setup menu.
Each degree can be subdivided into 60 minutes (and each minute into 60 seconds for very high precision).
In cases where the map (or GPS readout) is in degrees and minutes, you need to convert the minutes part to decimal parts of a degree, by dividing the number of minutes by 60, so for example.
50 deg 30 minutes north = 50.5 degrees
Dynamically generated satellite view image.
The viewpoint is random and changes every time you come here. The coastline is recalculated and redrawn just for you.
See here for Geostationary satellite view maps from all 10 deg longitude positions.
I have made you a degrees, minutes, seconds to decimal degrees calculator if you want to do it online.
|A latitude measuring experiment for you to try:
If you are in the northern hemisphere here is an interesting project suggestion. How about determining your latitude yourself by measurement ?. You need to go outside on a clear sky evening and look in a northerly direction and identify the Pole star or Polaris.
This star is in line with the earth's axis and if you measure the elevation angle of the star you determine your latitude.
You need to do two things, first Find the north pole star and Measure its elevation angle.
|Go to maps to see
an index page with a listing of all the map pages. Tell me if
you want a page made for your country.
This page started 2005, last amended 15 April 2010. Any problems, please email me, Eric Johnston
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