At this very moment 09/22/2004 at 11:30am is the Autumnal Equinox where there is exactly 12 hours of light and 12 hours of night at the equator. (thanks to tom’s blog for reminding me).
It’s noteworthy that this equal night/day thing is also occuring when just happens to be a half moon.
Both of these half phenomenons are all based on right angles. Here’s some fun diagrams.
The moon is at a right angle with the sun and earth.
The sun is at a right angle with the earth and its celestial equator. I wonder where the moon would be in this diagram.
: ) Thanks for the nod! I was going to post the very same diagram [the bottom one”> on my blog, but decided against it. I’m glad to see it here! Happy 1st Day of Fall, friend.
The other thing to note is that the first day of fall also marks the beginning of the Aurora Borealis “season”! According to spaceweather.com fall is the time of year when people are most likely to see the A.B. phenomenon!
Here’s a link to the spaceweather.com article on the Aurora Borealis season http://science.nasa.gov/headlines/y2002/23sep_auroraseason.htm