The Eye on the Sky weather forecast this morning noted that “The 18th of March features a sunrise at 6:58, setting at 7:00, with the length of the day totaling 12 hours and 2 minutes.”

What?!  I checked another source about the length of day and night and that source told me that on March 20 (the day of the official spring equinox, which occurs at 12:57 pm in Montpelier, VT) day will be 9 minutes and 8 seconds longer than night.

What does Spring Equinox actually mean, then?  Wikipedia reports that one of the definitions of equinox is, indeed, when day and night are the same length, but then goes on to cooly explain that “The equinox is not exactly the same as the day when day and night are of equal length for two reasons. Firstly, because of the size of the sun, the top of the disk rises above the horizon (constituting ‘sunrise’ which is the start of ‘daytime’) when the center of the disk is still below the horizon. Secondly, Earth’s atmosphere refracts sunlight which means that an observer can experience light (daytime) even before the first glimpse of the sun’s disk has risen above the horizon. To avoid this ambiguity the term equinox is sometimes used in this sense.”  

None of these explanations convince me that I haven’t somehow been sold down the river on the significance of the equinox.  

Who do I blame for this deception?  To whom do I complain?

 

How can the days be longer than the nights before the solstice? 

Advertisements