This post has been compiled from information posted on the internet and not written by me.
The longest day of 2013 is finally here—but this year, it comes with a twist!
While the solstice in the northern hemisphere traditionally falls on June 21— and this year it will occur on that date at 1:04 a.m. EDT— it will begin on Thursday, June 20, for parts of the western U.S., according to the website of the Clark Planetarium. The time of the solstice depends upon your position on Earth and, as a consequence, where you are in relation to the sun.
The summer solstice occurs when Earth's axis is the most tilted toward the sun—the angle is known as "maximum axial tilt." As a consequence of this specific orientation, the sun rises at its most northeasterly point along the horizon and also sets at its most northwesterly point in the northern hemisphere.
The solstice isn't the only big celestial event this week. Sky-watchers are gearing up for the arrival of the 2013 “super-moon”, which is set to peak June 22-23 and deliver the biggest, brightest moon of the year.
Solstice celebrations …
The term solstice can also be used in a wider sense, as the date (day) that such a passage happens. The solstices, together with the equinoxes, are connected with the seasons. In some languages they are considered to start or separate the seasons; in others they are considered to be center points (in England, in the Northern Hemisphere, for example, the period around the northern solstice is known as midsummer, and Midsummer's Day is 24 June, about three days after the solstice itself). Similarly 25 December is the start of the Christmas celebration, and is the day the Sun begins to return to the Northern Hemisphere.
Many cultures celebrate various combinations of the winter and summer solstices, the equinoxes, and the midpoints between them, leading to various holidays arising around these events. For the southern solstice, Christmas is the most popular holiday to have arisen. In addition, Yalda, Saturnalia, Karachun, Hanukkah, Kwanzaa and Yule (see winter solstice for more) are also celebrated around this time. For the northern solstice, Christian cultures celebrate the feast of St. John from June 23 to 24 (see St. John's Eve, Ivan Kupala Day, Midsummer), while Neopagans observe Midsummer, also known as Litha. For the vernal (spring) equinox, several spring-time festivals are celebrated, such as the Persian Nowruz, the observance in Judaism of Passover and in most Christian churches of Easter. The autumnal equinox has also given rise to various holidays, such as the Jewish holiday of Sukkot. At the midpoints between these four solar events, cross-quarter days are celebrated.
In many cultures, the solstices and equinoxes traditionally determine the midpoint of the seasons, which can be seen in the celebrations called midsummer and midwinter. In this vein, the Japanese celebrate the start of each season with an occurrence known as Setsubun. The cumulative cooling and warming that result from the tilt of the planet become most pronounced after the solstices, leading to the more recent custom of using them to mark the beginning of summer and winter in most countries of Central and Northern Europe, as well as in Canada, the USA and New Zealand.
In the Hindu calendar, two sidereal solstices are named Makara Sankranti which marks the start of Uttarayana and Karkat Sankranti which marks the start of Dakshinayana. The former occurs around January 14 each year, while the latter occurs around July 14 each year. These mark the movement of the Sun along a sidereally fixed zodiac (precession is ignored) into Makara, the zodiacal sign which corresponds with Capricorn, and into Karkat, the zodiacal sign which corresponds with Cancer, respectively.