What do we mean by the shortest day?
The shortest day, winter solstice and midwinter are the colloquial terms used to describe the 24 hours around an annual astronomical event which occurs around the 22nd December. The shortest day marks the point when the days start to get longer and the nights shorter, and has profound cultural meaning around the world and throughout history. The cultural significance varies, but generally refers to a time of rebirth and renewal and is celebrated with festivals and rituals.
The astronomical event of the solstice occurs when the angle of the Sun to an observer is at its greatest, for an observer in a given hemisphere. For the Northern hemisphere this will be when the Sun is at it's southern most position, and for an observer in the Southern hemisphere the northern most, see Figure 1.
The opposite of the winter solstice is the summer solstice and occurs around the 22nd June, and marks the point when the days are longest and nights shortest.
Timings for the summer and winter solstices are given in Table 1, summarised from the US Naval Observatory page at http://www.usno.navy.mil/USNO/astronomical-applications/data-services/earth-seasons
Figure 1: Winter solstice as seen by observer in Northern Hemisphere.
Some interesting related links
- Winter Solstice Brings Shortest Day of 2011 This Week (21/12/2011)
- Space.com article explaining the December 2011 winter solstice.
- Winter Solstice 2011: Facts on Shortest Day of the Year (22/12/2011)
- National Geographic article with some facts about the shortest day.
- Sky News: Winter solstice sees total lunar eclipse (21/12/2010)
- BBC Radio 4 Today programme: Lunar eclipse coincides with winter solstice (21/12/2010)
- Audio commentary from Dr David Whitehouse describing the first lunar eclipse to coincide with the winter solstice since 1638.
- BBC News: Winter solstice at Maeshowe on Orkney" (17/12/2010)
- An article from the BBC News for NE Scotland, Orkney and Shetland about the significance of the solstice to Neolithic people.
- Shropshire Star: UFO sighting linked to shortest day (07/01/2009)
- An article from the Shropshire Star about the shortest day being linked to an increase in UFO activity.
- BBC News: Hundreds celebrate shortest day (21/12/2008)
- An article from BBC News about the celebrations at Stonehenge in 2008.
Other Resources
- Autumnal Equinox
- The Autumnal Equinox is also known as the September Equinox and is one of two points in the calendar year when the rotational axis of the Earth is perpendicular to the line connecting the centres of the Sun and the Earth. This means that the day and night are essentially of equal length.
| 2000 | June | 21 | 01:48 | December | 21 | 13:37 |
| 2001 | June | 21 | 07:38 | December | 21 | 19:21 |
| 2002 | June | 21 | 13:24 | December | 22 | 01:14 |
| 2003 | June | 21 | 19:10 | December | 22 | 07:04 |
| 2004 | June | 21 | 00:57 | December | 21 | 12:42 |
| 2005 | June | 21 | 06:46 | December | 21 | 18:35 |
| 2006 | June | 21 | 12:26 | December | 22 | 00:22 |
| 2007 | June | 21 | 18:06 | December | 22 | 06:08 |
| 2008 | June | 20 | 23:59 | December | 21 | 12:04 |
| 2009 | June | 21 | 05:45 | December | 21 | 17:47 |
| 2010 | June | 21 | 11:28 | December | 21 | 23:38 |
| 2011 | June | 21 | 17:16 | December | 22 | 05:30 |
| 2012 | June | 20 | 23:09 | December | 21 | 11:11 |
| 2013 | June | 21 | 05:04 | December | 21 | 17:11 |
| 2014 | June | 21 | 10:51 | December | 21 | 23:03 |
| 2015 | June | 21 | 16:38 | December | 22 | 04:48 |
| 2016 | June | 20 | 22:34 | December | 21 | 10:44 |
| 2017 | June | 21 | 04:24 | December | 21 | 16:28 |
| 2018 | June | 21 | 10:07 | December | 21 | 22:22 |
| 2019 | June | 21 | 15:54 | December | 21 | 04:19 |
| 2020 | June | 21 | 21:43 | December | 21 | 10:02 |