Physics

Redshift Calculator

Find redshift and recession velocity from wavelengths.

Calculated Output

Redshift z 0.0056

Recession velocity (km/s) 1,690.13

Formula: z = (λ_obs − λ_rest) ÷ λ_rest

Step-by-Step Breakdown

1. Values used:

2. Rest wavelength = 656.3 nm

3. Observed wavelength = 660 nm

5. Redshift z = 0.0056

6. Recession velocity = 1,690.13km/s

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The math behind it

z = (λ_obs − λ_rest)/λ_rest. For small z, velocity ≈ c·z.

Hydrogen 656.3 nm seen at 660 nm → z ≈ 0.0056, about 1690 km/s.

Blueshift vs redshift?

Redshift means receding (longer λ); blueshift means approaching (shorter λ).