Thursday, September 23, 2010

Happy Equinox!!!

Today, September 23rd, is the first full day of autumn in the Northern Hemisphere and the first day of spring in the Southern Hemisphere.

My friend Bob Johnson from the World Union of Deists reminds us of what Thomas Paine said;
"The Equinox reminds us of the truth to this statement about the Creation being the only true word of God which Thomas Paine wrote in The Age of Reason: "It is only in the CREATION that all our ideas and conceptions of a word of God can unite. The Creation speaketh an universal language, independently of human speech or human language, multiplied and various as they may be. It is an ever-existing original, which every man can read. It cannot be forged; it cannot be counterfeited; it cannot be lost; it cannot be altered; it cannot be suppressed. It does not depend upon the will of man whether it shall be published or not; it publishes itself from one end of the Earth to the other. It preaches to all nations and to all worlds; and this word of God reveals to man all that is necessary for man to know of God."

The September Equinox Explained

The September equinox occurs at 03:09 (or 3:09am) Coordinated Universal Time (UTC) on September 23, 2010. It is also referred to as the autumnal or fall equinox in the northern hemisphere, as well as the spring or vernal equinox in the southern hemisphere (not to be confused with the March equinox). This is due to the seasonal contrasts between both hemispheres throughout the year.

The equinox will occur in the evening of September 22, 2010, for locations on US Eastern Daylight Time or further west. To find the September equinox date in other time zones or other years, please use the Seasons Calculator.

This illustration, which shows an example of the September equinox, is not to scale.

What happens during the September equinox?

The sun crosses the celestial equator and moves southward in the northern hemisphere during the September equinox. The location on the earth where the sun is directly overhead at solar noon is known as the subsolar point. The subsolar point occurs on the equator during the September equinox and March equinox. At that time, the earth’s axis of rotation is perpendicular to the line connecting the centers of the earth and the sun. This is the time when many people believe that the earth experiences 12 hours of day and night. However, this is not exactly the case.

Dispelling the “exactly 12 hours of daylight” myth

During the equinox, the length of night and day across the world is nearly, but not entirely, equal. This is because the day is slightly longer in places that are further away from the equator, and because the sun takes longer to rise and set in these locations. Furthermore, the sun takes longer to rise and set farther from the equator because it does not set straight down - it moves in a horizontal direction.

Moreover, there is an atmospheric refraction that causes the sun's disk to appear higher in the sky than it would if earth had no atmosphere. has a more detailed explanation on this topic. has more information on why day and night are not exactly of equal length during the equinoxes.

The vernal equinox occurs in the spring while the autumnal equinox occurs during fall (autumn). These terms are derivatives of Latin. It is important to note that the northern hemisphere’s vernal equinox is in March while its autumnal equinox is in September. In contrast, the southern hemisphere’s vernal equinox is in September and its autumnal equinox is in March.

This is a time to celebrate life! Spring and new life for the Southern Hemisphere. Harvest and plenty for the North.

Enjoy your spring or autumn Equinox!