`v = ((\Delta \lambda)/(lambda)) c`

599584.916

The Speed from Light Wavelength Shift calculator computes the relative speed of an object based on the shift in wavelength of the observed emitted light verses the normal (not shifted) wavelength of light emitted.

INSTRUCTIONS: Choose units and enter the following:

• (Δλ) Shift in wavelength of the light emitted.
• (λ) Wavelength of light (normal) emitted.

Relative Speed (v):  The calculator returns the relative velocity in meters per second.  However, this can be automatically converted to other velocity units via the pull-down menu.  

The Math / Science

For objects moving a speeds well below the speed of light there is a simple relationship between the speed of the object, the shift in the wavelength of the light emitted by the object, and the unshifted wavelength of the light (what the wavelength would be if the object were not moving). This equation computes that speed based on the other two numbers.

The formula for velocity based on light wavelength shift is:

   v = (Δλ / λ) * c

where:

• v = velocity 
• Δλ = shift in wavelength of light
• λ = base wavelength of light
• c = speed of light

Astronomy Calculators

• Kepler's 3^rd Law formula T² = (4π • R³)/(G • M)
  • (M) - mass of the system. 
  • (T) - period of the orbit.
  • (R) - separation distance between the two objects.
  • (G) - universal gravity constant
• Small Angle Formula
  • (α) - angle
  • (D) - distance to astronomical object
  • (S) - size or diameter of astronomical object
• Flux and Magnitude formulas
  • Change in Magnitude from Flux Ratio
  • Flux Ratio from Magnitudes
• Telescope formulas
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  • Magnification of a Telescope
• Mass formulas
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  • Mass from Acceleration and Radius
  • Mass from Speed and Separation
  • Mass of extra-solar planet from mass of star, radius of star orbit and radius of exoplanet orbit
  • Mass of extra-solar planet from mass and velocity of star and velocity of planet
• Relative Size Formulas
  • Relative Size from Relative Temperature and Luminosity
  • Relative Temperature from Relative Size and Luminosity
  • Relative Luminosity from Relative Temperature and Size
• Wavelength Formulas
  • Velocity from shift in Wavelength and Unshifted Wavelength
  • Wavelength Shift from Wavelength and Speed
  • Blackbody Wavelength from Temperature
  • Blackbody Temperature from Peak Wavelength
  • Photon Energy from Wavelength
  • Photon Wavelength from Energy
• Luminosity and other Formulas
  • Distance from absolute and apparent magnitude
  • Radius from Speed and Period
  • Speed of Circular Motion
  • Hubble Time
  • Luminosity from Mass

Related Astro Calculators:

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• Ellipse Calculator
• 3D Vector Calculator:
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• Exoplanet Calculator contains formulas for studying planets outside of our Solar System.
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