TKS Ephemeris · research · axial precession · 3D sky
Dhruva — the changing North Pole star
Drag the sky to turn it. The Earth's axis sweeps a cone (half-angle = the obliquity ≈ 23.4°) once in ~25,772 years, so the north celestial pole rides a circle across the stars — and the pole star changes: Thuban → Kochab → Polaris (today) → Errai → Vega. The pole's altitude equals your latitude.
2026 CE
Virtual sky · 3D
pole sky
⚠ |year| > ~5,000: the IAU-2006 F-W precession here extrapolates — the pole path/stars may be off (figure-eight). A Vondrák-2011 long-term module is required for the full cycle.
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At this epoch
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Dhruva timeline — which star, and for how long
live · ±30,000 yr
… computing …
Two distinct products: the reign = the interval (from→to) during which a given star is the nearest bright star to the pole (no angular threshold); and the closest approach = that star\'s actual minimum NCP separation (with its date) — these dates differ. Category is by the closest separation: ≤1° true pole star · 1–5° near-pole · 5–10° pole-marker/guide. Stars: Hipparcos/GAIA + proper motion; precession: Vondrák 2011. Live scan; ±200 kyr validity (few arcsec historical → few tenths of a degree at the edges).
Why? The Earth is a spinning top: the Sun & Moon pull on its equatorial bulge, so the axis slowly sweeps a cone. The axis — not the stars — moves; whichever bright star it points to is the “pole star”, and it changes over millennia. The pole's altitude above your horizon equals your latitude.