Saturday, March 19, 2011

Dear Rachel - A Note From Uncle Zah

Hi Rachel;

TOMORROW (SUNDAY)
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Did you know that in Raleigh tomorrow night the sun will set at 7:26pm.

And then just 5 minutes before at 7:21pm the Vernal Equinox will occur.

So what is the Vernal Equinox?  This is the time of year when the length of the day and the length of the night are the same.  The sun rises and then 12 hours later (1/2 of 24) it will set.  So the night is just as long as the day.

Every since last September the NIGHTS have been longer than the DAYS.

Starting tomorrow (well actually Monday) the DAYS will be longer than the NIGHTS.

Tomorrow is considered to be the start of spring by some folks an the middle of spring by other folks depending on how they figure it.

Another thing that happens on the DAY OF THE EQUINOX is the the location on the horizon where the sun rises is DUE EAST and the location on the horizon where the sun sets is DUE WEST.

So if you want to know "Which Way Is West" all you have to do is be outside tomorrow  (Sunday) when the sun sets and THAT WAY IS WEST!!!

Also tomorrow morning if you get up and go outside at 7:19AM you will see the sun rise and that way is DUE EAST!!!!

SOME MORE ABOUT THE EQUINOX
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If you know about the tilt of the earth's axis of rotation, you know it is tilted a little bit from being straight up and down when you think about the earth going around the sun.

The axis always sticks in the same direction.  That direction is always pointed right at the NORTH STAR.  

Because the axis is pointing the same way all the time and at the same time the earth goes around the sun in a big circle like path then sometimes the earth is tipped toward the sun and sometimes it it tipped away from the sun.  

When in it's orbit around the sun the earth is tipped away from the sun that makes the nights long and the days short and the weather cold. That is what makes winter.

When in it's orbit around the sun the earth is tipped toward the sun that makes the nights short and the days long and the weather warm.  That is what makes summer.

Then twice a year (in September and March) the axis is NOT pointed toward the sun or away from the sun and the days and nights are EQUAL.  Those times are called the Equinox.

There are two: One in the Autumn and one in the Spring.  The one in September is called the Autumnal Equinox and the one in March is called the Vernal Equinox. 

Tomorrow is the 'EQUAL-DAY' and the start of the days getting longer than the night and the start of warmer weather.

Your Uncle,

Zach