First Day of Fall 2012: Autumnal Equinox Marks Start of Longer Nights (PHOTO)

The first day of fall takes place Saturday with the Fall Equinox 2012 officially marking the end of the summer. The autumnal equinox also marks the precise day when day and night are theoretically of equal length.

In the coming weeks the days will begin to get shorter and the nights longer as the northern hemisphere shifts further into fall. That trend will continue all the way through to the winter solstice, which takes place on Dec. 21, and marks the longest night of the year.

The precise equinox taking place Saturday in fact occurred at 10.49 a.m. EDT - this is when the sun arrived at the intersection of the ecliptic and celestial equator.

For sky gazers today also sparks a new opportunity for them, as it is said that with today's seasonal change, people have a better chance of seeing the aurora borealis, otherwise known as the Northern Lights - a spectacular light show for those able to see it.

The Northern Lights occurs due to geomagnetic storms - disturbances in the Earth's magnetic field - which produce amazing light displays when charged particles from the sun smash into the Earth's magnetic field.

These occurrences are more common in the fall and spring than they are in the summer and spring.

The dates of the upcoming equinoxes and solstices are:

Winter Solstice on Dec. 21, 2012
Spring Equinox on March 20, 2013
Summer Solstice on June 21, 2013
Autumnal Equinox on Sept. 22, 2013