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To non-coronavirus news now - it's the first day of spring. For the first time in more than a century, the vernal equinox has fallen on March 19 nationwide. NPR's Rebecca Hersher reports.
REBECCA HERSHER, BYLINE: Good news - the earth is still going around the sun. And today is one of the two moments in its orbit when day and night are roughly equal everywhere. In the northern hemisphere, it's the first day of spring. And it's extra early this year. Wait a second, you might be thinking - if the first day of spring is a moment in the Earth's orbit, shouldn't it happen at the same time every year? And it would if there were exactly 365 days in a year. Michelle Thaller is an astrophysicist at NASA.
MICHELLE THALLER: So the problem is that we're happily spinning away on our axis, and the earth is going around the sun. But one year - one complete path around the sun isn't an even exact number of days and nights. It's 365.24 (laughter).
HERSHER: Because of the extra .24 days each year, we add a leap day every four years. So the time of the equinox moves six hours later each year for three years, and then February 29 happens and the clock gets turned back. And that would be that if the number of days in a year was 365 and a quarter - or .25. But it's not. It's .24.
So if we just kept having leap days every four years, our calendar would eventually be totally out of whack with the movement of the earth. So we skip leap days in years that are divisible by one hundred, like 1800 and 1900, except we keep the leap day in years that are divisible by 400, like the year 2000.
THALLER: In the year 2000, we had an extra leap day.
HERSHER: That leap day in 2000 turned back the clock. So this century, we're experiencing the equinox earlier. Then, it was just a matter of time zones and a thing about daylight saving time that I won't even get into. Suffice it to say, it took 20 more years after 2000 for all the major U.S. time zones to experience the equinox a day early, on March 19. So here we are.
And if all of this is a reminder of the profound unimportance of the human race to the vast and terrifying solar system, Michelle Thaller has a thought for you.
THALLER: You know, we're all on this little rotating rock together, and we're tiny. And the only thing we have is each other. You know, the only thing that's going to help the loneliness is each other.
HERSHER: So happy spring.
Rebecca Hersher, NPR News.
(SOUNDBITE OF ITZHAK PERLMAN PERFORMANCE OF VIVALDI'S "THE FOUR SEASONS - SPRING")
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