Each year we experience two equinoxes and two solstices. These four events are used to define our seasonal changes – officially that is.
Today is the autumnal or fall equinox in the northern hemisphere. An equinox is simply the point at which the sun crosses the equator and day and night are of equal length. In the northern hemisphere the fall equinox occurs in September (a slightly different day each year). It’s the opposite in the southern hemisphere.
Today, September 23rd at 4:21 am the sun crossed the equator and the fall equinox began. The fall equinox leads to the winter solstice when the night is the longest and day is the shortest (around Dec 22nd). Again, the opposite in the southern hemisphere. As the daylight hours reduce it gets colder, hence why the coming solstice officially kicks off the season of winter.
In Reality……..
The truth is the further north you live the earlier you start to experience the seasonal changes so although the equinox and solstice are good rules of thumb as to the seasonal changes and associated weather (brrrr!) they are not absolute.
Before I forget though, welcome to the first day of Fall 2015. (Unless you live in the southern hemisphere than it’s the opposite.)
Of course if you live on or near the equator the seasonal changes are minimized. It’s sort of like your weather is just one season year round.
Who figured this out and how did they do it?
Sometimes I wonder how human kind figured out the mechanics of the seasons, the cause (that is, earth orbiting the sun, earth rotating). I only know this because I was taught in school and it makes sense, so I believe it (and I guess Wikipedia say’s it’s true too so it must be). It might be strange but I wonder if I was not taught about the earths obit and rotation would I have been able to figure it out.
It is actually pretty fabulous that others did all the analysis for us, does leave me wondering about my own capabilities though.
Again Happy Fall 2015 and don’t forget to bring in the tomatoes before they freeze on the vine – they won’t turn red and are not really edible after that.