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In this activity, students examine the first line of evidence, galactic motion, for the notion of an expanding universe. By examining the spectrum of light from a galaxy, students can determine whether a galaxy is moving toward or away from us, and how fast. Students will look at optical images of four galaxies, compare the emission spectra from these same four galaxies, and measure the wavelength of the red hydrogen line for each galaxy. This activity is part of the "Cosmic Questions" educator's guide developed to support the Cosmic Questions exhibit. This activity can be used in conjunction with, or independently of, the exhibit.
This resource is located on page 48 of the PDF document.