How to Calculate a Red Shift

A "redshift" is the displacement of an astronomical object toward the red end of the color spectrum, meaning that its light wave is lengthening. This change in length indicates that the source of waves and the observer are both in rapid motion in relation to each other. In astronomical terms, this indicates that objects are pulling away from the observing point of view. The length of the redshift is directly proportional to the distance increased, therefore calculating the span of red light indicates how far the distance between those two object increased during that time.

Things You'll Need

• Calculator

Show More

Instructions

1. • 1

     Determine and record the total observed wavelength of light between the two objects.

   • 2

     Record the rest wavelength of the light between the objects. Rest wavelength is the spectral line between two objects when there is no motion in respect to each other.

   • 3

     Place these values into the equation (observed wavelength - rest wavelength) / (rest wavelength) = z, where z equals the value of the redshift. A positive value for z indicates that the two objects have increased in distance.