OK, so what's the big whoopee, you may wonder? Well, in my experience this is one of those things people hear about, but haven't a clue as to what it means. So I am here to clear up this little matter.

OK, here we go: as you may (or may not) know, the axis of the earth's rotation is tipped 23 & 1/2 degrees from the plane of the ecliptic. (Big fancy words, easily imagined as thus: picture a big piece of paper stuck in the Sun at it's equator. The planets would be rolling around the sun in their orbits on that piece of paper. This paper represents the "plane of the ecliptic;" it's a spatial orientation thing.)

Anyway, this means that as the revolves about the Sun, it does not rotate like a ball spinning upright. It's axix does not make a 90 degree angle with the plane of it's orbit. It's tipped.

Ok, so what's the big deal? Well, if it didn't have a tipped axis, we wouldn't have the seasons. But it does, and so during part of its orbit the Northern Hemisphere is pointed at the sun, and during another part of its orbit the Southern Hemisphere is pointed in that direction. (This is why when it's summer here, it's winter in New Zealand.)

During the summer months when the northern hemisphere is pointed toward the sun, we in this hemisphere have more hours of daylight than we do night. The opposite is true during our winter, when the southern hemisphere is pointed that way. The times of year where we have the most hours of daylight versus night is called the June Solstice; when we have the least hours of daylight and most hours of night is the December Solstice.

OK, midway between the earth reaches a position in its orbit where the axis is oriented to where it points toward its orbital path, and not the sun. On these days, the spinning earth is heated equally from pole to pole, as all parts of it receive 12 hours of daylight and 12 hours of night. These are the Equinoxes; the term "equinox," by the way, means "equal night."

The equinoxes have always been of special meaning to ancient cultures. I believe Stonehenge was built with the main "doorway" looking out to that point where the sun rises on the vernal equinox (spring). We use that point as the starting place in determining right and left ascension of star positions, too. When you use a circle as a measuring device, you need some sort of starting point!

Oh yeah, in closing, it is proper to refer to the solstices and equinoxes as the "March Equinox," "June Solstice," September Equinox," and "December Solstice." Remember, the earth has a northern and a southern hemisphere; this lessens confusion when speaking of this subject!

And now you know more than you ever really wanted to about this sort of thing!