Earth's Seasons and Apsides
Equinoxes, Solstices, Perihelion, and Aphelion
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You can obtain the dates of the seasons (equinoxes and solstices) and apsides (perihelion and aphelion) of the orbit of the Earth by typing the year (1700-2100) in the space below and clicking on the "Find dates" button.

Use Form A for Universal Time, or time zones in the U.S. or its territories. Use Form B for all other time zones. Both forms are immediately below.

Form A - U.S. Time Zones



No Yes

Form B - International Time Zones

Time Zone:    
Need a time zone?  Try the time zone map.


The calculator provides the computed times of the beginning of the seasons as well as Earth's perihelion and aphelion. The times of the equinoxes mark the beginning of spring and fall. The times of the solstices mark the beginning of summer and winter. Definitions of these terms can be found in The Astronomical Almanac Online glossary.

Variation in Times of Perihelion and Aphelion explains why the times of these events appear to vary more than those of the others while The Seasons and the Earth's Orbit discusses how all of these phenomena relate.

Time Zones

For U.S. time zones (Form A), phenomena times are presented in the standard time or daylight time (see below) requested. Standardized time zones were introduced in the U.S. in 1883.

For worldwide time zones (Form B) that require it, the time zone can be entered in hours and a fraction. For example, for locations in India, the time zone may be entered as 5.5 hours east of Greenwich. The time zone field can accommodate up to five characters.

Daylight Time

In accordance with the Uniform Time Act of 1966 and subsequent legislation, daylight time (DST) can be implemented only for U.S. time zones (Form A) from 1967 to the present day.

Application Programming Interface

This data service uses one of our new Application Programming Interfaces (APIs). The API returns data in JavaScript Object Notation (JSON) format for users who wish to manipulate data into a customized format. For more information on the API, please see the documentation page.

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