# Which is the great circle?

A great circle is any circle that divides the earth into a circumference of two equal halves. Examples of small circles include all lines of latitude except the equator, the Tropical of Cancer, Tropic of Capricorn, the Arctic Circle, and Antarctic Circle.
A Great Circle is any circle that circumnavigates the Earth and passes through the center of the Earth. A great circle always divides the Earth in half, thus the Equator is a great circle (but no other latitudes) and all lines of longitude are great circles.
For example, the Prime Meridian at 0° is half of a great circle. On the opposite side of the globe is the International Date Line at 180°. The only line of latitude, or parallel, characterized as a great circle is the equator because it passes through the exact center of the Earth and divides it in half.
A rhumb line, also called a loxodrome, is a line of constant bearing. For example, if you steer your ship or airplane on a constant bearing of, say, 045°, you will be following a rhumb line. A great circle is the line formed by the intersection of a plane through the earth’s centre and the earth’s surface.

how many great circles are there? A great circle is created by any line that slices through the center of a sphere. Great circles on Earth are roughly 40,000 kilometers (24,855 miles) all the way around.

What is the longest parallel?

Why are latitudes parallel?