September President's Message
The equinox is coming! The equinox is coming! The equinox is coming on September 22 at 9:29 p.m.
I will get to the equinox in a bit, but first, our PAS meeting is coming! It is the first Friday this month, September 5. The meeting will be back on UNO's campus in Room 1001 of the Science Building. The meeting starts at 7:30 p.m. Our very own Paul McDonald will present on stargazing in the national parks of the southwest. Also, if you plan to attend this year's Deep South Regional Star Gaze, Barry Simon will be on hand to answer your questions.
The autumnal or September equinox marks the beginning of autumn. It also marks a specific point in the Earth's orbit and a unique occurrence in the daytime sky. On September 22 at 9:29 p.m. Central Daylight Time, the Earth reaches the halfway point in its orbit between the solstices. In the daytime sky, the Sun's path across the sky intersects the celestial equator.
The celestial equator is a projection of the Earth's equator onto the night sky. If you were at the equator looking up at the sky, the celestial equator will be an imaginary line across the sky starting on the eastern horizon, going straight overhead and ending at the western horizon. An equinox marks the time when the Sun's path crosses this imaginary line.
Basically, the Sun appears to rise directly in the east and set directly in the west on the equinox. This September equinox is another great chance to start your study of the analemma. Also, the Sun's path across the sky is called the ecliptic in case you were wondering.
I hope to see you at this month's meeting, and be sure to ask me about the Full Harvest Moon.