The equinoxes, solstices and seasons only exist because the axis of rotation of the Earth is at an angle of
23.4 degrees, to the vertical with respect to the plane (the ecliptic) formed by the revolution of the Earth about the Sun.
Because the Earth's axis is directed at the same point in space as it revolves around the Sun, the angle of tilt of the axis with respect to the Sun varies, from a minimum of 0 degrees (which defines the equinoxes) to a maximum of 23.4 degrees toward or away (which defines the summer and winter solstices, respectively).
Southern Hemisphere |
|
Northern Hemisphere |
|
|
|
The change in angle between the southern end of the Earth's axis and the ecliptic for 1 year (ie. 1 revolution).
Positive values indicate tilt toward the Sun. |
|
The change in angle between the northern end of the Earth's axis and the ecliptic for 1 year (ie. 1 revolution).
Positive values indicate tilt toward the Sun. |
The subsolar point is the point on the Earth's surface where the Sun's radiation strikes at a 90 degree angle; alternatively it is the point on the Earth where the Sun is directly overhead at noon.
|
June Solstice |
Equinoxes |
December Solstice |
|
Subsolar point |
Tropic of Cancer |
Equator |
Tropic of Capricorn |
|
|
23.4 degrees N |
0 degrees |
23.4 degrees S |
|
Because the Earth's orbit is slightly elliptical, there is a point on the orbit where the Earth is further away from the Sun than at any other time (Aphelion, ~July 4) and a point approximately opposite on the orbit where the Earth is closer to the Sun than at any other time (Perihelion, ~Jan 3).
The times for equinoxes and solstices (as well as aphelion & perihelion) are shown on the U.S. Navy web site , for Greenwich, England. An explanation of Universal Time (UT), which approximates to Greenwich Mean Time (GMT), is given on the same site.
Melbourne, Australia: |
|
Longitude: 145° 08' East |
Event |
March Equinox |
Tue, 20 Mar 2012, 4:14 PM. EDT |
|
GMT values have been converted to Australian Eastern Standard Time (GMT + 10), and are shown below:
Note: Add 1 hour to obtain correct local times for the December Solstice and March Equinox for the states in Australia that change to Australian Eastern Daylight Time during the warmer months.
|
|
March Equinox
Autumn |
|
June Solstice
Winter |
|
September Equinox
Spring |
|
December Solstice
Summer |
|
2001
|
|
Mar 20
|
23:31
|
|
Jun 21
|
17:38
|
|
Sep 23
|
9:04
|
|
Dec 22
|
5:21
|
|
2002
|
|
Mar 21
|
5:16
|
|
Jun 21
|
23:24
|
|
Sep 23
|
14:55
|
|
Dec 22
|
11:14
|
|
2003
|
|
Mar 21
|
11:00
|
|
Jun 22
|
5:10
|
|
Sep 23
|
20:47
|
|
Dec 22
|
17:04
|
|
2004
|
|
Mar 20
|
16:49
|
|
Jun 21
|
10:57
|
|
Sep 23
|
2:30
|
|
Dec 21
|
22:42
|
|
2005
|
|
Mar 20
|
22:33
|
|
Jun 21
|
16:46
|
|
Sep 23
|
8:23
|
|
Dec 22
|
4:35
|
|
2006
|
|
Mar 21
|
4:26
|
|
Jun 21
|
22:26
|
|
Sep 23
|
14:03
|
|
Dec 22
|
10:22
|
|
2007
|
|
Mar 21
|
10:07
|
|
Jun 22
|
4:06
|
|
Sep 23
|
19:51
|
|
Dec 22
|
16:08
|
|
2008
|
|
Mar 20
|
15:48
|
|
Jun 21
|
9:59
|
|
Sep 23
|
1:44
|
|
Dec 21
|
22:04
|
|
2009
|
|
Mar 20
|
21:44
|
|
Jun 21
|
15:45
|
|
Sep 23
|
7:18
|
|
Dec 22
|
3:47
|
|
2010
|
|
Mar 21
|
3:32
|
|
Jun 21
|
21:28
|
|
Sep 23
|
13:09
|
|
Dec 22
|
9:38
|
|
2011
|
|
Mar 21
|
9:21
|
|
Jun 22
|
3:16
|
|
Sep 23
|
19:05
|
|
Dec 22
|
15:30
|
|
2012
|
|
Mar 20
|
15:14
|
|
Jun 21
|
9:09
|
|
Sep 23
|
0:49
|
|
Dec 21
|
21:12
|
|
2013
|
|
Mar 20
|
21:02
|
|
Jun 21
|
15:04
|
|
Sep 23
|
6:44
|
|
Dec 22
|
3:11
|
|
2014
|
|
Mar 21
|
2:57
|
|
Jun 21
|
20:51
|
|
Sep 23
|
12:29
|
|
Dec 22
|
9:03
|
|
2015
|
|
Mar 21
|
8:45
|
|
Jun 22
|
2:38
|
|
Sep 23
|
18:20
|
|
Dec 22
|
14:48
|
|
2016
|
|
Mar 20
|
14:30
|
|
Jun 21
|
8:34
|
|
Sep 23
|
0:21
|
|
Dec 21
|
20:44
|
|
2017
|
|
Mar 20
|
20:28
|
|
Jun 21
|
14:24
|
|
Sep 23
|
6:02
|
|
Dec 22
|
2:28
|
|
2018
|
|
Mar 21
|
2:15
|
|
Jun 21
|
20:07
|
|
Sep 23
|
11:54
|
|
Dec 22
|
8:22
|
|
2019
|
|
Mar 21
|
7:58
|
|
Jun 22
|
1:54
|
|
Sep 23
|
17:50
|
|
Dec 22
|
14:19
|
|
2020
|
|
Mar 20
|
13:49
|
|
Jun 21
|
7:43
|
|
Sep 22
|
23:30
|
|
Dec 21
|
20:02
|
|
Number of times for a particular date:
| |
|
Mar 20
|
10
|
|
Jun 21
|
15
|
|
Sep 22
|
1
|
|
Dec 21
|
5
|
|
|
|
Mar 21
|
10
|
|
Jun 22
|
5
|
|
Sep 23
|
19
|
|
Dec 22
|
15
|
|
Toronto, Canada: |
|
Longitude: 79° 22' West |
Event |
March Equinox |
Tue, 20 Mar 2012, 1:14 AM. EDT |
|
GMT values have been converted to Eastern Standard Time (GMT - 5), and are shown below:
Note: Add 1 hour to obtain correct local times for the March Equinox, June Solstice and September Equinox for the areas that change to Eastern Daylight Time during the warmer months.
|
|
March Equinox
Spring |
|
June Solstice
Summer |
|
September Equinox
Autumn |
|
December Solstice
Winter |
|
2001
|
|
Mar 20
|
8:31
|
|
Jun 21
|
2:38
|
|
Sep 22
|
18:04
|
|
Dec 21
|
14:21
|
|
2002
|
|
Mar 20
|
14:16
|
|
Jun 21
|
8:24
|
|
Sep 22
|
23:55
|
|
Dec 21
|
20:14
|
|
2003
|
|
Mar 20
|
20:00
|
|
Jun 21
|
14:10
|
|
Sep 23
|
5:47
|
|
Dec 22
|
2:04
|
|
2004
|
|
Mar 20
|
1:49
|
|
Jun 20
|
19:57
|
|
Sep 22
|
11:30
|
|
Dec 21
|
7:42
|
|
2005
|
|
Mar 20
|
7:33
|
|
Jun 21
|
1:46
|
|
Sep 22
|
17:23
|
|
Dec 21
|
13:35
|
|
2006
|
|
Mar 20
|
13:26
|
|
Jun 21
|
7:26
|
|
Sep 22
|
23:03
|
|
Dec 21
|
19:22
|
|
2007
|
|
Mar 20
|
19:07
|
|
Jun 21
|
13:06
|
|
Sep 23
|
4:51
|
|
Dec 22
|
1:08
|
|
2008
|
|
Mar 20
|
0:48
|
|
Jun 20
|
18:59
|
|
Sep 22
|
10:44
|
|
Dec 21
|
7:04
|
|
2009
|
|
Mar 20
|
6:44
|
|
Jun 21
|
0:45
|
|
Sep 22
|
16:18
|
|
Dec 21
|
12:47
|
|
2010
|
|
Mar 20
|
12:32
|
|
Jun 21
|
6:28
|
|
Sep 22
|
22:09
|
|
Dec 21
|
18:38
|
|
2011
|
|
Mar 20
|
18:21
|
|
Jun 21
|
12:16
|
|
Sep 23
|
4:05
|
|
Dec 22
|
0:30
|
|
2012
|
|
Mar 20
|
0:14
|
|
Jun 20
|
18:09
|
|
Sep 22
|
9:49
|
|
Dec 21
|
6:12
|
|
2013
|
|
Mar 20
|
6:02
|
|
Jun 21
|
0:04
|
|
Sep 22
|
15:44
|
|
Dec 21
|
12:11
|
|
2014
|
|
Mar 20
|
11:57
|
|
Jun 21
|
5:51
|
|
Sep 22
|
21:29
|
|
Dec 21
|
18:03
|
|
2015
|
|
Mar 20
|
17:45
|
|
Jun 21
|
11:38
|
|
Sep 23
|
3:20
|
|
Dec 21
|
23:48
|
|
2016
|
|
Mar 19
|
23:30
|
|
Jun 20
|
17:34
|
|
Sep 22
|
9:21
|
|
Dec 21
|
5:44
|
|
2017
|
|
Mar 20
|
5:28
|
|
Jun 20
|
23:24
|
|
Sep 22
|
15:02
|
|
Dec 21
|
11:28
|
|
2018
|
|
Mar 20
|
11:15
|
|
Jun 21
|
5:07
|
|
Sep 22
|
20:54
|
|
Dec 21
|
17:22
|
|
2019
|
|
Mar 20
|
16:58
|
|
Jun 21
|
10:54
|
|
Sep 23
|
2:50
|
|
Dec 21
|
23:19
|
|
2020
|
|
Mar 19
|
22:49
|
|
Jun 20
|
16:43
|
|
Sep 22
|
8:30
|
|
Dec 21
|
5:02
|
|
Number of times for a particular date:
| |
|
Mar 19
|
2
|
|
Jun 20
|
6
|
|
Sep 22
|
15
|
|
Dec 21
|
17
|
|
|
|
Mar 20
|
18
|
|
Jun 21
|
14
|
|
Sep 23
|
5
|
|
Dec 22
|
3
|
|
