(based on Earth's position relative to the Sun)
(the longest and shortest days of the year). Because a full orbit takes approximately 365.24 days, these dates shift slightly each year. in the Northern Hemisphere, the astronomical timeline is: Starts March 20 (Vernal Equinox) and ends June 20. Starts June 21 (Summer Solstice) and ends September 21. Fall (Autumn): when do the four seasons start and end
(Note: Dates for the Southern Hemisphere are reversed. When it is astronomical summer in the north (June 21), it is astronomical winter in the south.) Spring: March, April, May Summer: June, July, August
In the Southern Hemisphere:
Implications