Stellafane
Village Idiot.
- Joined
- Apr 14, 2006
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I am not sure if Ptolemy catalogued the stars in Orion's belt, I would have to go do some digging. They all have Arabic proper names (Alnitak, Alnilam, and Mintaka) if you are looking them up. In addition, you may want to throw in the star positions calculated by Tycho Brahe, as they are close to your 500-year mark, and are famous for their accuracy. It also gives those people interested another easily researched and verified data point.
I'm pretty sure Ptolemy cataloged the stars in Orion's belt, because they're bright and it's an important constellation. But his positions would probably be of limited value for this purpose. Although he was reasonably accurate, he used a coordinate system different from the one we now use. Instead of using the celestial poles and equator as references, Ptolemy measured a star's position relative to the ecliptic (see here). Thus his measurements must be converted into modern coordinates to be useful for comparison. (Prolemy was accurate enough, however, for Edmund Halley to assume the fact that the Almagest placed Sirius one degree away from its position in Halley's time was evidence that the star itself must have moved, rather than due to measurement error. Halley was correct of course, and thus discovered proper motion of stars.)
ETA: The stars in Orion's Belt actually would be good "landmarks" because they're relatively far away and therefore less subject to proper motion. Thus the major factor in any change of position over the course of a few thousand years would be mostly due to precession.
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