This is the coordinate system that we use on Earth. It
is measured in angular units: degrees, minutes, and seconds.
There are 60 minutes in a degree, and 60 seconds in a minute.
||Latitude is the angular distance north or south of
the equator. The equator is the middle location
on the Earth's surface, and is located halfway between
the North and South poles.
|If a line is drawn from any point on the Earth's
surface to the center of the Earth, the angle that line
makes with the equator is that location's latitude.
The diagram on the right shows the equator (highlighted
in red), as well as other lines of latitude and
The North Star (Polaris) is located directly above
the North Pole. This means that the altitude of the
North Star in the sky is equal to the latitude of the
person observing it. If you are at 90 degrees North
latitude (the North Pole), Polaris will be 90 degrees
above the horizon (directly overhead).
As shown in the example to the right, this method
will work for any location in the northern hemisphere.
The girl in the diagram must be at 42 degrees North
||Longitude is the angular distance east or west of the
Prime Meridian. The Prime Meridian is designated
as 0 degrees longitude, and passes through Greenwich,
|The diagram on the right shows the Prime Meridian
(highlighted in red), as well as other lines of latitude
Solar noon is defined as being the time at which the
sun reaches its highest point in the sky. Since the
Earth rotates on its axis at a rate of 3600
per day, it rotates at a rate of 150
per hour (3600
divided by 24 hours). This means that the occurrence of
solar noon will move from east to west at a rate of 150
per hour. Longitude can be calculated, if
when solar noon occurs, the observer knows what time it
is at the Prime Meridian. By determining how many hours
difference there is between you and the Prime Meridian,
you can calculate how many degrees of longitude away you
are (using the formula of 150