Answer Happy

Exercise 3: The Distance to the Andromeda Galaxy The distance to the Cepheid variable star also gives us the distance to the Andromeda galaxy (after all, the star is inside Andromeda). We can get the distance to the Cepheid by comparing its luminosity to its apparent brightness and using the inverse square law: Equation 2. B L 47d² L 4TB You just figured out the luminosity, L. The apparent brightness can be found from these images just by measuring the amount of light received. It is: B = 1.92 x 10-16 W/m² (Watts per meter squared). Use luminosity, L from Exercise 2, and apparent brightness, B given above, with equation 2 to calculate the distance to Andromeda in meters. Now convert to light years by multiplying it by 1.46 x 10-16 m/LY. Distance to Andromeda: d= m, d= light years Now check your answer in your astronomy notes or online to see if it makes sense.