6) The redshift of a galaxy is observed to be 1.5. Calculate the recessional velocity of the galaxy.

• Redshift takes place when the source is moving away from the observer. This reduces the frequency which will in turn increase the wavelength shifting the spectrum to the red side.

• The velocity at which the source is moving away from the observer will be given by,

$\boxed{\frac{\mathbf{v}}{\mathbf{c}}\mathbf{=}\frac{{\left(z+1\right)}^{\mathbf{2}}\mathbf{-}\mathbf{1}}{{\left(z+1\right)}^{\mathbf{2}}\mathbf{+}\mathbf{1}}}$

Here v is the recessional velocity, c is the speed of light, and z is the redshift.