The June Solstice
An example of what happens during the June solstice. Illustration is not to scale
June Solstice in San Francisco, California, U.S.A. was on
Saturday, June 21, 2014 at 3:51 AM PDT (Change city)
The June solstice is known as the summer solstice in the northern hemisphere and the winter solstice the southern hemisphere. The date varies between June 20 and June 22, depending on the year.
Varying dates
In the Gregorian calendar the June solstice dates vary. For example, it occurs on June 21 in 2014 and 2015 but on June 20 in 2016. A June 22 solstice will not occur until June 22, 2203. The last time there was a June 22 solstice was in 1971.
The varying dates of the solstice are mainly due to the calendar system – most western countries use the Gregorian calendar, which has 365 days in a year, or 366 days in a leap year. As for the tropical year, it is approximately 365.242199 days, but varies from year to year because of the influence of other planets. A tropical year is the length of time that the sun takes to return to the same position in the cycle of seasons, as seen from Earth. The exact orbital and daily rotational motion of the Earth, such as the “wobble” in the Earth's axis (precession), also contributes to the changing solstice dates.
Seasons, Equinoxes and Solstices
The June solstice explained
A solstice occurs when the sun's zenith is at its furthest point from the equator. During the June solstice it reaches its northernmost point and the Earth’s North Pole tilts directly towards the sun, at about 23.5 degrees. It is also known as the northern solstice because it occurs when the sun is directly over the Tropic of Cancer in the northern hemisphere. If the Earth's rotation was at right angles to the plane of its orbit around the sun, there would be no solstice days and no seasons.
The June solstice day has the longest hours of daylight for those living north of the equator. Those living or travelling to the north of the Arctic Circle are able to see the “midnight sun”, where the sun remains visible throughout the night, while those living or travelling south of the Antarctic Circle will not see sun during this time of the year. For those living near the equator, the sun does not shift up and down in the sky as much compared with other geographical locations away from the equator during this time of the year. This means that the length of day temperature does not vary as much.
The June solstice marks the first day of the summer season in the northern hemisphere. The word solstice is from the Latin word “solstitium”, meaning “sun-stopping”, because the point at which the sun appears to rise and set stops and reverses direction after this day. On this day, the sun does not rise precisely in the east, but rises to the north of east and sets to the north of west allowing it to be in the sky for a longer period of time. In the southern hemisphere, the June solstice is known as the shortest day of the year. It is when the sun has reached its furthest point from the equator and marks the first day of winter.
Moving to other seasons
©iStockphoto.com/Bojan Tezak
After the June solstice, the sun follows a lower and lower path through the sky each day in the northern hemisphere until it reaches the point where the length of daylight is about 12 hours and eight to nine minutes in areas that are about 30 degrees north or south of the equator, while areas that are 60 degrees north or south of the equator observe daylight for about 12 hours and 16 minutes. This is called the September equinox, which is also known as the autumnal equinox in the northern hemisphere. Many regions around the equator have a daylight length about 12 hours and six-and-a-half minutes during the equinox.
It is important to note that Earth does not move at a constant speed in its elliptical orbit. Therefore the seasons are not of equal length: the times taken for the sun to move from theMarch equinox to the June solstice, to the September equinox, to the December solstice, and back to the March equinox are roughly 92.8, 93.6, 89.8 and 89.0 days respectively. The consolation in the northern hemisphere is that spring and summer last longer than autumn and winter.
Useful Tools
The World Clock can also be used to find sunrise and sunset times, as well as the current position of the sun in major cities around the world. Simply select any location that is available from the World Clock and the calculator will adjust the local time in that particular city.
Solstice’s influence on cultures
In ancient times, solstices and equinoxes were important in guiding people to develop and maintain calendars, as well as helping them to grow crops. It was important for many people, especially those who spent a considerable amount of time outdoors, to understand the seasons and weather, which played a key role in their lives. Over the centuries, the June solstice was a time when festivals, celebrations and other festivities were celebrated.
Astronomy calculators
More information
Calendar tools
Related time zone tools
Nancy Atkinson on Google+
