Lab Exercises in Astronomy: Hubble's Law

"It is a remarkable fact that a vital clue to the nature of the universe is revealed by a very simple observation." In this astronomy lab exercise, students verify Hubble's Law and determine the Hubble constant, thereby calculating the age of the universe. The lab exercise should take 2 hours or so, though it can be shortened as needed.

Hubble’s constant, which gives the rate of the expansion of the universe, is of basic significance in modern cosmology. This exercise clearly presents one way of deriving this quantity from observational data. The redshifts of five elliptical galaxies are measured from their spectra, and the distances of the same galaxies are found from their angular sizes on photographs. By plotting the galaxies’ redshifts against their distance, Hubble’s constant is determined, leading to a discussion of the universe’s age and size, Prepared by Aneurin Evans, University of Keele.