Submitted by vaterp t3_z10idk in askscience
derioderio t1_ixaorek wrote
Reply to comment by Grundyloop in How do astronomers share coordinates with each other? by vaterp
Why don't they just use Earth's rotation axis, or Polaris? Is that because Earth's axis wobbles slightly, and the star positions slowly change over 1000s of years?
Blakut t1_ixc15bm wrote
they do. Earth's north pole projected onto the sky is the North Celestial Pole, and Earth's equator is projected onto the sky to give the Celestial Equator. Where the Sun's path in the sky intersects the Celestial Equator in spring defines the zero point.
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