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SolsticeFrom Wikipedia, the free encyclopediaJump to: navigation, search
For other uses, see Solstice (disambiguation).
UTC date and time of solstices and equinoxes[1]
year Equinox
Mar Solstice
June Equinox
Sept Solstice
Dec
day time day time day time day time
2004 20 06:49 21 00:57 22 16:30 21 12:42
2005 20 12:33 21 06:46 22 22:23 21 18:35
2006 20 18:26 21 12:26 23 04:03 2200:22
2007 21 00:07 21 18:06 23 09:51 22 06:08
2008 20 05:48 20 23:59 22 15:44 21 12:04
2009 20 11:44 21 05:45 22 21:18 21 17:47
2010 20 17:32 21 11:28 23 03:09 21 23:38
2011 20 23:21 21 17:16 23 09:04 22 05:30
2012 20 05:14 20 23:09 22 14:49 21 11:12
2013 20 11:02 21 05:04 22 20:44 21 17:11
2014 20 16:57 21 10:51 23 02:29 21 23:03
2015 20 22:45 21 16:38 23 08:20 22 04:48
2016 2004:30 20 22:34 22 14:21 21 10:44
2017 20 10:28 21 04:24 22 20:02 21 16:28

A solstice is an astronomical event that happens twice each year when the Sun's apparent position in the sky, as viewed from Earth, reaches its northernmost or southernmost extremes. The name is derived from the Latin sol (sun) and sistere (to stand still), because at the solstices, the Sun stands still indeclination;[citation needed] that is, the apparent movement of the Sun's path north or south comes to a stop before reversing direction.

The term solstice can also be used in a broader sense, as the date (day) when this occurs. The solstices, together with the equinoxes, are connected with the seasons. In some cultures they are considered to start or separate the seasons, while in others they fall nearerthe middle.

Contents [hide]
1 Definitions and frames of reference
2 Heliocentric view of the seasons
3 Geocentric view of the seasons
4 Cultural aspects
4.1 Ancient Greek names and concepts
4.2 English names
4.3 Solstice terms in East Asia
4.4 Solstice celebrations
4.5 Solstice determination
5 See also
6 References
7 External links
7.1 Calculations, plots and tables
7.2 Debateabout season start


[edit] Definitions and frames of referenceOf the many ways in which solstice can be defined, one of the most common (and perhaps most easily understood) is by the astronomical phenomenon for which it is named, which is readily observable by anyone on Earth: a "sun-standing." This modern scientific word descends from a Latin scientific word in use in the late Roman republicof the 1st century BC: solstitium. Pliny uses it a number of times in his Natural History with the same meaning that it has today. It contains two Latin-language morphemes, sol, "sun", and -stitium, "stoppage."[2] The Romans used "standing" to refer to a component of the relative velocity of the Sun as it is observed in the sky. Relative velocity is the motion of an object from the point of view ofan observer in a frame of reference. From a fixed position on the ground, the sun appears to orbit around the Earth.[3]

To an observer in an inertial frame of reference, the planet Earth is seen to rotate about an axis and revolve around the Sun in an elliptical path with the Sun at one focus. The Earth's axis is tilted with respect to the plane of the Earth's orbit and this axis maintains aposition that changes little with respect to the background of stars. An observer on Earth therefore sees a solar path that is the result of both rotation and revolution.

The component of the Sun's motion seen by an earthbound observer caused by the revolution of the tilted axis – which, keeping the same angle in space, is oriented toward or away from the Sun – is an observed daily increment(and lateral offset) of the elevation of the Sun at noon for approximately six months and observed daily decrement for the remaining six months. At maximum or minimum elevation, the relative yearly motion of the Sun perpendicular to the horizon stops and reverses direction.

The maximum elevation occurs at the summer solstice and the minimum at the winter solstice. The path of the Sun, or...