The vernal equinox, which marks the first day of spring in the Northern Hemisphere, has equal parts night and day. Depending on the year, this can vary between March 19, 20, and 21. A March 21 equinox hasn’t happened in the continental United States since 1979 and won’t happen again until the 22nd century.

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What’s the Difference Between a Solstice and an Equinox?

You may know that the solstices and equinoxes signal the changing of the seasons on Earth, but do you remember which is which? Are they just different names for the same thing? Actually, a solstice and an equinox are sort of opposites. The seasons on Earth change because the planet is slightly