In a distant galaxy, an emission line of hydrogen that has a rest wavelength of 656 nm has an observed wavelength of 662.6 nm. Is the galaxy moving away from us or toward us? How fast is it moving in (km/sec)?
velocity = ((shifted wavelength - rest wavelength)(c)) / rest wavelength
The Attempt at a Solution
velocity = ((6.626 x 10^-10 km - 6.56 x 10^-10 km)(3 x 10^5 km)) / 6.56 x 10^-10 km = 3018 km/sec
My answer is: the galaxy is moving away from us at 3018 km/sec. I'm hoping someone can tell me if this answer is correct. My instructor assigned this as a homework question and will be using it as a quiz question as well, so it's a double whammy if I don't have the right answer.