Physics / Astronomy
Speed of light from Io
Roemer 1676: Io's eclipses arrive late when Earth is far from Jupiter, and the residuals of the fit measure the speed of light.
What happens
Roemer 1676: Io's eclipses arrive late when Earth is far from Jupiter, and the residuals of the fit measure the speed of light. Circular coplanar orbits and ideal periodic eclipses. The joint fit estimates the period and light delay together.
t_k = a + bk + d_k/c + ε_k
Equations used in the module
Equations t_k = t₀ + kP + d_k/c + ε_k; P ≈ 42.46 h min Σ_k [t_k − (a+bk+q d_k)]²; c = 1/q d_k [m], t_k [s], q [s/m] 2 AU/c ≈ 998 s ≈ 16.6 min c → ∞: q → 0
