04Time Machine
The sky across twenty-six thousand years
The zodiacs are clocks set against different references. Turn time back and watch the equinox, the pole and the signs move against the stars, and read one moment as nine traditions would have written it.
01Ptolemy
Tropical: true ecliptic and equinox of dateSidereal: tropical longitude minus the ayanamsa, LahiriWhat would Ptolemy have seen?
Ptolemy anchored the zodiac to the seasons. Slide from 500 BCE to today and watch the tropical signs drift across the stars and away from the sidereal ones.
Today the two zodiacs are 24°14′ apart (Lahiri); the equinox lies in Pisces.
Open the instrument02Precession
Star-fixed: mean ecliptic and equinox of J2000.0Equatorial: true equator and equinox of dateThe 26,000-year axis
Earth's axis sweeps a slow cone. Follow the celestial pole from Thuban past Polaris toward Vega, over twenty-six thousand years.
Polaris is 0°38′ from the pole today; Polaris comes closest in 2102 CE (0°28′).
Open the instrument03Historical Sky
Tropical: true ecliptic and equinox of dateSidereal: tropical longitude minus the ayanamsaOne moment, nine traditions
Babylonian, Hellenistic, Hipparchus, Ptolemy, Islamic, medieval, Renaissance, modern tropical and modern sidereal: the same sky in each one's frame, with its history and sources.
The Sun now: 1°41′ Libra tropical, 7°27′ Virgo sidereal (Lahiri).
Open the instrument
Precession changes the relationship between Earth's equatorial coordinate system and the distant stellar background. It does not physically move the planets into different locations.