Astronomy
The Summer Solstice

The Summer Solstice Explained



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The Summer Solstice
Jose Juan Gutierrez's image for:
"The Summer Solstice Explained"
Caption: The Summer Solstice
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Image by: Andrew Dunn
© Creative Commons Attribution-Share Alike 2.0 Generic license. http://commons.wikimedia.org/wiki/File:Sun_behind_the_Heel_Stone.jpg

The summer solstice occurs when the Earth´s axial tilt reaches its highest point at 23° 26´ altitude either north or south of the equator. During the solstices, the Hemispheres are most inclined towards the Sun. The summer solstice occurs twice a year around June 20-22 in the Northern Hemisphere, and around December 20-23 in the Southern Hemisphere. The day of the solstice can be either the longest or shortest day of the year for any region outside of the tropics. The term solstice is of Latin origin ¨sol¨ means sun and ¨sistere¨ means to stand still. The day of the summer solstices is usually the day when there is more daylight.

Solstices and equinoxes

The summer solstice occurs once a year in the Northern Hemisphere; hence its name because it occurs in the summer, while in the Southern Hemisphere is the winter solstice. Half of a year later, the Southern Hemisphere experiences the summer solstice, while the Northern Hemisphere experiences the winter solstice. Halfway between the solstices are the equinoxes, which are the times when the ecliptic, the path on which the Sun travels, crosses the equator, which occurs around March 20 and September 22.

Summer solstice in the Northern Hemisphere

The Earth completes an orbit around the Sun in a year. During its travel around the Sun, the Earth´s axis tilts gradually, experiencing the seasons. In the summer its tilt has gotten as far as 23° 26´ north of the equator, and as it continues orbiting the Sun, it reaches the autumnal equinox, the time of the season when the ecliptic and the equator meet. Then it continues until it reaches the winter solstice, which is when the Sun has gotten at 23° 26´ south of the equator, and appears at its lowest altitude in the horizon. As the Earth continues orbiting the Sun, it then reaches the vernal equinox around March 20-21, and three months later, the summer solstice again.

Summer solstice in the Southern Hemisphere

Likewise, when in the Southern Hemisphere is experiencing the summer solstice, the axial tilt of the Earth has reached 23° 26´ south of the equator, which is the furthest the Earth´s tilt can get, and as it continues orbiting the Sun, it reaches the autumnal equinox, which is when the ecliptic crosses the equator. Another three months later, it reaches the winter solstice, which is when the Sun is seen at its lowest point in the northern sky at 23° 26´ north of the equator. Three months later, is the vernal equinox, which is when the ecliptic crosses the equator, and finally it reaches the summer solstice again.

The summer solstices occur in both hemispheres; however, they occur within a six month period of time one from the other. While in the Northern Hemisphere we are experiencing the summer solstice, in the Southern Hemisphere, they´re experiencing the winter solstice, and six months later, while in the Southern Hemisphere, they´re experiencing the summer solstice, in the Northern Hemisphere, we are experiencing the winter solstice. Halfway between these two margins are the equinoxes, when days and nights are of equal length.

Over the course of a year, the Sun displaces itself back and forth along the horizon. At the time of the solstices the Sun´s path on the horizon appears to have stopped, and this is the time when the Sun has reached its highest or lowest points in the sky, after which the sun´s path on the horizon is reversed. The solstices, along with the equinoxes are related to the seasons. According to windows2universe.org, the height that the Sun reaches in your region depends on the season, as well as your latitude.

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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://scienceworld.wolfram.com/astronomy/SummerSolstice.html
  • InfoBoxCallToAction ActionArrowhttp://www.windows2universe.org/the_universe/uts/summer.html