Summer Solstice 2009 Facts and Trivia

The word solstice comes from the Latin solstitium or sol (the sun) + -stit-, -stes (standing).

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. Because of the Earth's tilt, the sun will be directly over the Tropic of Cancer at 1145 pm MDT on June 20, 2009. 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 winter solstice occurs when the sun is directly over the Tropic of Capricorn, which is located at 23.5° latitude South of the equator and runs through Australia, Chile, southern Brazil (Brazil is the only country that passes through both the equator and a tropic), and northern South Africa. The winter solstice marks the shortest day of the year in the Northern Hemisphere and will occur at 1047 am MST on December 21, 2009.

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. This means that the distance between the Earth and Sun, which is 93 million miles on average, varies throughout the year. During the first week in January, the Earth is about 1.6 million miles closer to the sun. This is referred to as the perihelion. The aphelion, or the point at which the Earth is about 1.6 million miles farther away from the sun, occurs during the first week in July. This fact may sound counter to what we know about seasons in the Northern Hemisphere, but actually the difference is not significant in terms of climate and is NOT the reason why we have seasons. Seasons are caused by the fact that the Earth is tilted on its axis by 23.5°.

The summer solstice occurs when the sun is directly over the Tropic of Cancer, which is located at 23.5° North, and runs through Mexico, the Bahamas, Egypt, Saudi Arabia, India, and southern China. Because of the Earth's tilt, the sun will be directly over the Tropic of Cancer at 1145 pm MDT on June 20, 2009. 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. As stated above, the winter solstice occurs when the sun is directly over the Tropic of Capricorn, which is located at 23.5° south of the equator.

There are two times of the year when the Earth's axis is tilted neither toward nor away from the sun, resulting in an equal amount of daylight and darkness at all latitudes. These events are referred to as equinoxes and occur near March 21 (Vernal Equinox) and near September 21 (Autumnal Equinox). At the equator, the sun is directly overhead at noon on the two equinoxes. The Vernal Equinox occurred at 544 am MDT on March 20, 2009. The Autumnal Equinox will occur at 318 pm MDT on September 22, 2009.

For a complete listing of the dates of the winter and summer solstice's and spring and fall equinox's through 2020, check out this site from the U.S. Naval Observatory.

*****