The heavenly bodies do their seasonal dance and shift their steps tomorrow. We call it it the start of autumn, though is another hemisphere they will be entering spring.
The Autumnal Equinox 2010 will occur September 22 at 11:09 PM EDT.
Some science teacher probably tried to get you to understand that an equinox is either of two points on the celestial sphere where the ecliptic and the celestial equator intersect. Eventually, you could grasp that it was one of two times each year when the Sun crosses the equator, and the day and night are of approximately equal length.
Four seasons but two equinoxes.
When the Sun passes this point on about 23 September each year, the nights begin to grow longer than the days. They will continue to do so until the Winter Solstice in December.
As an October baby, I have always preferred autumn to summer. Cooler weather, sweaters, colored forests. Even the beach is better in September to me. No crowds, no badges, few tourists, no blazing sun to hide from.
Though we mark this time as the beginning of autumn in the Northern Hemisphere, folks on the other side of the globe are marking the start of spring with their vernal equinox.
That’s a tough concept to wrap your mind around. The sun will continue to shift southward, bringing cooler weather to we Northerners, and warmer weather to the Southern Hemisphere.
People often confuse the solstice and equinox. The Summer and Winter Solstices mark when the Sun is farthest north or south and the length of time between Sunrise and Sunset is the shortest of the year while the equinoxes mark the equal points in between.
Enjoy the cool breeze. Rub your hands and enjoy that first evening that you catch a wood fire from a distance. Brew a cup of tea.
For more information more about why we have changing seasons, go to http://crh.noaa.gov/fsd/astro/season.php.