"Why is the Summer Triangle Overhead on the First Night of Fall?"

Scheduled air date: 2001 Sep 17-23

Friday, September 22nd marks the beginning of Fall (or Autumn) in the Northern Hemisphere, when the Sun appears directly on the Celestial Equator.

As a result, the Sun will rise exactly due East the morning of September 22nd...

...and set exactly due West that evening.

Because of Daylight Saving Time, the Summer Triangle can be seen nearly directly overhead shortly after dusk at the beginning of Autumn...

...and the constellations of Autumn (e.g. Pegasus, Cassiopeia, Perseus) are instead visible over the Eastern horizon.
(Shown about 80 minutes after Sunset for mid-Northern latitudes.)

If you wish to view illustrations for other episodes, please see our Star Gazer Illustrated directory.

Illustrations on this page were created using TheSky Astronomy Software, an advanced desktop planetarium program designed for Windows.

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