Equinox
| UTC Date and Time of solstices and equinoxes | ||||||||
|---|---|---|---|---|---|---|---|---|
| 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 | 22 | 00:22 |
| 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 | 11:11 |
| 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 | 20 | 04:30 | 20 | 22:34 | 22 | 14:21 | 21 | 10:44 |
| 2017 | 20 | 10:28 | 21 | 04:24 | 22 | 20:02 | 21 | 16:28 |
An equinox is when the sun passes directly over the equator. There are two equinoxes each year. Equinox can also mean either of the two days when this happens. On these days, the nights are equal in length at latitudes L° North and L° South. The word equinox comes from two Latin words meaning "equal" and "night".
Around the day of the equinox, the length of the day is a little over twelve hours and the length of the night is a little under twelve hours. They are not exactly equal because the sun is not a point in the sky and because the sunlight bends as it comes to earth. The exact day and time when this happens depend on how far away from the equator it is being measured. They occur on or around March 21 and September 21. Solstices fall around June 21st and December 21st at odd intervals.
The equinoxes are the beginning of spring, and autumn (or fall in the US).
The time of daylight is quite easy to measure. This was done in many cultures where festivals were celebrated at the equinoxes.
Equinox Media
Contour plot of the hours of daylight as a function of latitude and day of the year, showing approximately 12 hours of daylight at all latitudes during the equinoxes
Earth at the September 2022 equinox
Diagram showing the Celestial sphere with ecliptic and equinoxes
Diagram of the difference between the Sun's celestial longitude being zero and its declination being zero. Its celestial latitude never exceeds 1.2 arcseconds, but is exaggerated in this diagram.
Day arc at 20° latitudeThe Sun culminates at 70° altitude and its path at sunrise and sunset occurs at a steep 70° angle to the horizon. Twilight still lasts about one hour.
Day arc at 50° latitudeTwilight lasts almost two hours.
Day arc at 70° latitudeThe Sun culminates at no more than 20° altitude and its daily path at sunrise and sunset is at a shallow 20° angle to the horizon. Twilight lasts for more than four hours.
Day arc at 90° latitude (pole)If it were not for atmospheric refraction, the Sun would be on the horizon all the time.
Related pages
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