Question

Which of the following latitudes is a great circle?
A. Equator
B. ${66}^{\circ }\text{N}$
C. ${20}^{\circ }\text{S}$
D. ${23}^{\circ }\text{S}$

Answer 1

Hint: Latitude and longitudes are imaginary lines used for pointing a position on the surface of a planet. Latitudes translate into circles on a planet, which are parallel to each other. A great circle is a circle whose plane also passes through the center of that planet.

Complete answer: While longitudes are half circles running from pole to pole, latitudes are complete circles. Longitudes converge at poles and are measured east and west of the prime meridian (zero degrees). Latitudes are parallel to the equator and measured North or South of it. These two combined help us to pinpoint a location on the surface. Maps are the biggest example of, where these circles are represented as straight lines and display the curved surface of the earth as flat. One example of this is a map, either printed or digital. The biggest use of maps is in the maritime industry and the aviation industry. Big maps of various scales are required for plotting a path for sailing from one place to another. The concept of a great circle is important because, for two places on a planet, the shortest possible distance will always fall on a great circle. This helps sailors and pilots in planning the shortest route possible for their journey. This saves time and fuel and eventually cuts down the overall emissions. The Equator is the only latitude which is a great circle.

Thus, option (A) is correct.

Note:On Earth's surface, great circles translate into straight lines but when they are plotted on a chart (flat maritime map), they come out to be curved lines.