View source for Celestial sphere

==Parts of the Celestial Sphere==

There are parts of the celestial sphere that are useful to know when talking about where things are in the night sky or defining the various coordinate systems used to locate objects in the sky.

=== Celestial Equator and Celestial Poles ===
[[Image:Pole_equator.png|right|thumb|200px|The Celestial Equator and Poles]]
If you project the Earth's equator onto the night sky you produce an imaginary line across the sky known as the celestial equator. This means that if you were standing on the Earth's equator looking due east, the celestial equator would start at the horizon, go straight up overhead and then down due west directly behind you. The height above the ground the celestial equator appears depends on how close you are (in [[latitude]]) to the Earth's equator. As with the terrestrial equator on the ground, the celestial equator divides the sky into northern and southern hemispheres.

If you project the Earth's geographic/terrestrial [[Earth's poles|pole]] out onto the celestial sphere, you would then create the north and south celestial poles. Thus if you were to stand on one of the Earth's poles the and looked straight up you would be looking in the direction of one of the celestial poles (north if you were standing on the Earth's north pole, south if you were standing on the south pole). As with the celestial equator the height of the celestial pole depends on your latitude. In fact the height above the northern horizon of the north celestial pole is your latitude (change to the southern pole and horizon for south of the terrestrial equator).

[[Category:Astronomical concept]]