Vera C. Rubin Observatory will detect millions of previously unknown supernovae and faint galaxies, providing a wealth of data that reveals that the Universe is expanding and that the rate of expansion is changing with time. Students examine the expansion rate of the Universe for different galaxies, and learn that the Universe appears to be expanding uniformly regardless of location. Together, these observations provide evidence to support the Big Bang theory.

Prerequisite Concepts

• Students should understand the idea of “lookback time” and that light from a distant object provides us information about what that object (and the Universe) was like in the past.

• Students should be familiar with the idea that distant galaxies appear to be moving away from us, with farther away galaxies moving faster, leading to the idea that the Universe is expanding.

• Students should be familiar with the idea that it is the spacetime of the Universe that is expanding and causing galaxies to appear to be moving away.

Learning Outcomes

• Students analyze and interpret a Hubble Plot to explain the relationship between a galaxy’s recessional velocity and its distance.

• Students use models to demonstrate that the Universe has no center.

• Students use Hubble plots to provide evidence for the expansion rate of the Universe over time.

• Students use data to argue how the idea of expansion provides supporting evidence for the Big Bang Theory.

Essential Questions

• How do we know that the Universe is expanding?
• What do observations of the expansion of the Universe tell us about our location in the Universe?
• How do we know that the expansion of the Universe is accelerating?
• How does the observed expansion of the Universe support the Big Bang Theory?