4/5/2023 0 Comments When does spring start 2021![]() The United States, most of North America, Europe and many countries in the Northern Hemisphere use astronomical spring to determine when spring season officially starts and ends. The March equinox occurs in the Northern Hemisphere between the dates of March 19 to 21 followed by the Summer solstice - June 20 to 22 and then the September equinox - September 21 to 23 and finally the Winter solstice - December 20 to 23. When the sun is over the equator you have the equinoxes and when the sun is over the Tropic of Cancer in the most northern position you have the Summer solstice and conversely when the sun is over the most southern position over the Tropic of Capricorn you have the Winter solstice. The tilt of the earth does not change as it goes around the sun so in the Northern Hemisphere the earth is tilted toward the sun in June and away from the sun in December. Seasons are caused by the tilt of the earth on its axis by 23.5 degrees. For countries located west of UTC your spring will start earlier than countries located east of UTC.Īstronomical Spring is determined by the changing positions of the earth relative to the sun giving us the solstices and equinoxes. ![]() This is referred to as astronomical spring or the March equinox or vernal equinox.Īstronomical spring starts at different times around the planet because of the different time zones as related to Coordinated Universal Time (UTC, same as Greenwich Mean Time based on the Royal Observatory in Greenwich, London ). The first day of spring (March equinox or vernal equinox) is when the sun shines directly on the celestial equator passing from south to north and the length of day and night are almost the same. ![]()
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