«
»

Autumnal Equinox 2009

Posted by BC on September 14th, 2009

   Autumnal Equinox for 2009 is 22 Sept. at 21:19 UT. What does that mean?

I will be glad for autumn again. The cooler season generally brings more stable air and shuts down the mosquito population as well as the pollen that fills the air. The season change also means that the stars in the night sky are advancing overhead, and we have different objects to view. The summer sky is full of wondrous objects, and the summer Milky Way is awesome, but the winter sky is just as appealing.

One person has commented

Sophtware said,

“Equal hours of daytime and nighttime”

Actually, this will never happen. If the sun were just a pin-point on the horizon, it might. But since the sun has a very large diameter, we have to take into account the radius of the sun that is still setting when crossing over the horizon. Because of this, during the equinox there is more daylight than nighttime. Not by much, but daylight is still longer. Probably by a few minutes at most.


Leave a Comment

 

Article Sections

Astronomy articles
Solar System Guide
Space Exploration
Cosmology articles
Book Reviews

Features

Night Sky Guide
Buying a Telescope
Historical Eclipses
Meet Astronomers
Astrophotography
The Constellations

Our Community

Read blog posts
Our newsletter
Meet the Team