Empirical Earth · The Sky — Sun, Moon & Stars

Star trails

The claim

“Star trails are just stars wheeling over a flat disc.”

What is measured

Long-exposure photos show stars circling two opposite points, one over each pole, the mark of a single rotating sphere, not a dome over a disc. See also pole stars and precession and the southern sky.

What would show this is wrong

star trails not circling two opposite celestial poles, or sharing a single center worldwide.

Sources

  1. IERS Conventions. Sidereal rotation period and Earth-orientation parameters. International Earth Rotation and Reference Systems Service. Earth rotation / IERS link
  2. Pole stars & axial precession. Standard positional astronomy — Polaris and σ Octantis; ≈25,772-yr precession cycle; Thuban (~2700 BC) and Vega (~13,700 AD) as past/future pole stars (Meeus, link
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