This means that the distance between the Earth and Sun, which is 93 million miles on average, varies throughout the year. We all know that the Earth makes a complete revolution around the sun once every 365 days, following an orbit that is elliptical in shape.
Naval Observatory. An alternative text link is found here. In the Northern Hemisphere, it occurs when the sun is directly over the Tropic of Capricorn, which is located at 23.5° south of the equator and runs through Australia, Chile, southern Brazil, and northern South Africa.įor a complete listing of the dates of the winter and summer solstices and spring and fall equinoxes through 2025, check out this site from the U.S. The winter solstice marks the shortest day and longest night of the year. For every place north of the Tropic of Cancer, the sun is at its highest point in the sky and this is the longest day of the year. The summer solstice occurs when the sun is directly over the Tropic of Cancer, which is located at 23.5° latitude North and runs through Mexico, the Bahamas, Egypt, Saudi Arabia, India, and southern China. Therefore, on the day of the summer solstice, the sun appears at its highest elevation with a noontime position that changes very little for several days before and after the summer solstice. The summer solstice occurs at the moment the earth's tilt toward/from the sun is at a maximum. Therefore, on the equinox and for several days before and after the equinox, the length of day will range from about 12 hours and six and one-half minutes at the equator, to 12 hours and 8 minutes at 30 degrees latitude, to 12 hours and 16 minutes at 60 degrees latitude. Additionally, the days become a little longer at the higher latitudes (those at a distance from the equator) because it takes the sun longer to rise and set. The "nearly" equal hours of day and night are due to refraction of sunlight or a bending of the light's rays that causes the sun to appear above the horizon when the actual position of the sun is below the horizon. At the equator, the sun is directly overhead at noon on these two equinoxes. The word equinox is derived from two Latin words - aequus (equal) and nox (night).
These events are referred to as Equinoxes. There are only two times of the year when the Earth's axis is tilted neither toward nor away from the sun, resulting in a "nearly" equal amount of daylight and darkness at all latitudes.
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