- Precession: North Pole drift
- Is Polaris always the north star?
- When will Polaris be closest to true north?
- What was the north star when the Great Pyramid of Khufu
(Cheops) was built?
- What will be the north star 2000 years from now?
- What is the period of precession?
- Sky chart showing north pole drift during
- Precession: Equatorial slip
- What happens to the right ascension of Orion during
- How does the celestial equator appear to slide along the
- Imagine that a star is located exactly at the location of
the September equinox.
- Where will that star be located at the next September
- At a September equinox a hundred or a thousand years
- Imagine that you are riding the sun in its course around
the ecliptic. Which is longer, a sidereal year or a tropical
- In what way does an equinox "precede" the stars it was
associated with before? (This is "precession of the
- Does the angle between the ecliptic and celestial equator
remain at 23.5 degrees, or does it change with precession?
- Why is your horoscope hopelessly out of
- Hipparchos of Nicaea discovered precession around 150 B.C.
using Babylonian records and some ingenious mathematics.
- Further study:
- Examine Crowe's modern explanation of the cause of
precession on pp. 8&endash;10, Theories of the World from
Antiquity to Copernicus.
- See also Bob Berman, Secrets of the Night Sky,
"Puzzles of the Pole Star," pp. 80-89.