How does the prime Meridian divide the earth?
Because the earth is more or less a sphere, it can be divided in half various ways. One way is to draw a line between the two poles, such that each pole is at the center of a hemisphere. That line is the equator. Dividing the earth in half the other way (with the line running from pole to pole) is harder, because there is no obvious center reference (like the two poles going the other way). The “prime meridian” was chosen arbitrarily because it ran through the best observatory available at that time, so measuring where it was seemed easier than elsewhere. To answer your question, the prime meridian (if run all the way around the earth) is an arbitrary line that cuts the earth in half at a right angle to the way the equator cuts it in half. It has no real importance other than the fact that it has become convenient to use it (rather than other meridians).
