Diurnal Motion in the Northern Hemisphere

Celestial Equator

The sky's diurnal or apparent daily motion around the poles gives rise to the celestial equator, a circle lying directly overhead the Earth's equator.
From our northern latitude of 35 degrees in Shawnee, Oklahoma, the celestial equator rises on the horizon straight east, arcs upward to cross the meridian at an altitude of 55 degrees (= co-latitude = 90 - 35), and descends to intersect the horizon in the west.
From night to night and season to season the position of the celestial equator in our sky remains the same.

Sun

On any given day the Sun will follow a path roughly parallel to the celestial equator.
During the northern hemisphere summer the Sun rides high, above the celestial equator, crossing the meridian near the zenith.
During the northern hemisphere winter the Sun travels low, between the celestial equator and the horizon.

Equatorial Constellation

In the northern hemisphere an equatorial constellation rises in the east (on the left as one faces south). Note the angle the celestial equator makes with the horizon to an observer facing east from Shawnee, 35 degrees north latitude.
As seen from this latitude, is Orion's belt nearly vertical as it rises in the east?
Consider the star Mintaka, the northernmost star of Orion's belt, which lies nearly on the equator. Every 24 hours Mintaka rises in the east, follows the path of the celestial equator to cross the meridian at one's colatitude, and then sets in the west. Watch the constellation Orion in the planetarium as it follows this diurnal cycle.
Note that Orion's two shoulder-stars, Betelgeuse and Bellatrix, are seen above Rigel, the bluish-white star of his bright left foot.

Next: Circumpolar Constellations

Star chart created with Voyager II Software for Macintosh, published by Carina Software. This is just a taste of what Voyager can do! For info on Voyager II software, call Carina Software at (510) 355-1266, write them at 12919 Alcosta Blvd Suite #7, San Ramon, CA 94583, or visit Carina Software's home page and check out Voyager II for yourself.