Sunlit Design > InfoSearch > Seasons of the Year
Index: A-D, E-R, S-Z
A
- Accuracy of Sundials
- A.D. Years
- Altitude, Solar
- Angle above Horizon, Solar
- Apparent Time
- "Astronomical Algorithms"
- Astronomical Calculations, Time Basis of
- Azimuth, Solar
- Daylight Saving Time
- Declination, Solar
- Degrees, Minutes and Seconds
- Degrees of Rotation
- Dynamical Time
Seasons of the Year
The Seasons of the Year: summer, autumn, winter and spring are marked astronomically by the Equinoxes and Solstices. These solar events occur as the earth moves around the sun and reaches points in it's orbit that are integral multiples of 90 degrees.Equinoxes and Solstices
Informally, the Equinoxes in March and September are the times of the year when the length of day and night are the same and when solar declination is 0.
More rigorously, the (Vernal) Equinox in March is defined as the 0 point in reckoning the progress of the earth in orbiting the sun. When the earth orbits 180 degrees away from this point the September Equinox occurs.
The June and December Solstices occur when the earth has reached 90 degrees and 270 degrees respectively in it's orbit around the sun.
Informally the Solstices the times of year when the day is of minimum and maximum length and and when solar declination is at it's minimum and maximum.
Times of Equinoxes and Solstices 2000-2004
| 2000 | Equinoxes | March | 20 07:35:21.4770 [UT] | September | 22 17:27:35.9507 [UT] |
| Solstices | June | 21 01:47:46.2446 [UT] | December | 21 13:37:31.1415 [UT] | |
| 2001 | Equinoxes | March | 20 13:30:52.6748 [UT] | September | 22 23:04:30.6638 [UT] |
| Solstices | June | 21 07:37:54.4232 [UT] | December | 21 19:21:30.7143 [UT] | |
| 2002 | Equinoxes | March | 20 19:16:15.1619 [UT] | September | 23 04:55:25.2033 [UT] |
| Solstices | June | 21 13:24:22.2168 [UT] | December | 22 01:14:30.2728 [UT] | |
| 2003 | Equinoxes | March | 21 00:59:53.8487 [UT] | September | 23 10:46:51.5557 [UT] |
| Solstices | June | 21 19:10:20.1759 [UT] | December | 22 07:03:46.4641 [UT] | |
| 2004 | Equinoxes | March | 20 06:48:36.7287 [UT] | September | 22 16:29:49.0017 [UT] |
| Solstices | June | 21 00:56:48.7443 [UT] | December | 21 12:41:32.0381 [UT] |
Calculate it!
The Sun API provides the sdxFindAnnFeat function to find the times of the following seasonal events:
- Solstice in June
- Solstice in December
- Equinox in March
- Equinox in September
- Maximum Equation of Time in May
- Maximum Equation of Time in November
- Minimum Equation of Time in February
- Minimum Equation of Time in July
- Zero Equation of Time in April
- Zero Equation of Time in June
- Zero Equation of Time in September
- Zero Equation of Time in December
- Maximum Declination
- Minimum Declination
- Zero Declination in March
- Zero Declination in September
- Crossing point of Analemma in April
- Crossing point of Analemma in August