Question: I live in Bethesda Maryland. Today is March 17. The forecast shows sunrise at 7:16 AM and sunset at 7:18 PM. Yesterday it was 7:17 AM to 7:17 PM. But the equinox is still three days away. How is this possible? I thought the word “equinox” literally meant “equal night.” —Matthew Koll, Bethesda, MD
Answer: I’ve gotten this question before, so I figured it was about time to do a post explaining the Equinox in more detail. The word “equinox” does indeed mean “equal night (and day)”. See the etymology here. And this would seem to require sunrise at exactly X:00 am and sunset at exactly X:00 pm. Obviously, that doesn’t quite happen. It’s close, but no cigar. There’s a lot of misconceptions about the Equinox, not the least of which is that myth about “balancing an egg.”
The graphic above was sent with this week’s question. It’s the kind of printout provided by many websites and mobile apps, and it’s what prompted Matthew’s question. It shows the data for March 17, three days before the official Equinox date.
The first thing to know is: Although the Equinox happens on a specific calendar date (March 20), it actually ...