To pinpoint your position on a map of the world you need to work out your co-ordinates, known as latitude and longitude. Latitude is your position north or south of the Equator. Lines, or parallels, are drawn around the Earth at intervals. The North Pole is assigned the latitude 90º north and the South Pole latitude 90º south.
Lines of longitude, or meridians, are drawn a little differently. The line of longitude corresponding to 0º, which passes through Greenwich in London, is called the Prime (or Greenwich) Meridian. Longitude lines run along the Earth’s surface in a north–south direction, and unlike latitude lines, they divide the globe into segments like those of an orange, rather than regular strips.
It’s possible to measure latitude by comparing your position on Earth with the position of either the sun or the North Star (Polaris). Measurements using the sun are possible on a clear day in the northern or southern hemispheres, when the sun is easy to find. However, measurement of latitude isn’t as straightforward as you might think. Accurate readings can only be taken at noon, when the sun is at its highest in the sky. To complicate matters further, the sun rises higher in summer than in winter, and this must be allowed for in any calculation.
Being so far away and only one of a myriad stars visible to the naked eye, the North Star isn’t as easy to find as the sun. Furthermore, you can only see it at night, which isn’t always convenient. Its major limitation, however, is that it isn’t visible from the southern hemisphere.
For our purposes, we shall therefore assume that we’re in the northern hemisphere. You can use a simple quadrant to measure latitude using either the sun or the North Star.
Picture Credit : Google