What determines the time of sunrise and sunset?
During a recent trip to the Andaman Islands, I noticed that the sunrise and sunset times in the city of Port Blair were almost exactly an hour earlier than those in my hometown of Bengaluru in mainland India. My father believed that sunrise and sunsets are determined by the latitude, while my mother said that it was caused by the longitude. Both cities follow the same time zone (UTC+5.5hrs), which prompted me to study the factors that determine the sunrise and sunset times for a particular place. Longitude The Earth has 360 degrees longitude which runs from 180 degrees in the West to 180 degrees in the East. The longitude of a particular place denotes its location with respect to the Prime Meridian. As the Earth rotates from West to East, places further east will experience sunsets and sunrises earlier. Since 360 degrees of longitude corresponds to one whole day, we can calculate that 1 degree corresponds to a 4-minute time difference for the sun’s movement (assuming both places are ...