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Expanding Universe

Investigation total duration
1.5 hours

Videos and Auxiliary Content

Videos and Slides

These resources are from a teacher workshop on this investigation. They include a talk from a cosmologist (15 minute video) and the accompanying talk visuals (speaker slides).

Video: Keith Bechtol, "The Expanding Universe as Seen with Vera C. Rubin Observatory"

Speaker slides


The Hoberman Sphere video used as the phenomenon for this investigation may be revisited and used for discussion at the end of the lesson.

Options for Extended Exploration

  1. Hubble’s original plot (shown on page 1 of the investigation) shows three points that have a velocity less than zero (a negative velocity). Ask students to reason what this means (they are blueshifting/approaching). What could that indicate about these galaxies’ positions in space?
  2. Examine the slope of the graph produced by the large volume of Rubin Observatory data. Where does the slope of the curve change? What time (in years before present) does that translate to? Ask students to read about what astronomers think may have caused this change.
  3. Calculate the age of the Universe based on your determination of the value of the Hubble Constant (H). The units for the Hubble Constant are km/sec/Mpc. The age in years (t) is inversely related to the Hubble Constant: t = 1/H. Start by using your determined value for the Hubble Constant. First use dimensional analysis to convert megaparsecs (Mpc) to km and then cancel the units. Finally, convert seconds to years.

Make Your Own Rubin Voices Trading Card

Use this activity:

  • To encourage students to imagine themselves in a STEAM career.
  • To Introduce the diversity of people and occupations involved in Observatory operations.
  • As a "get to know you" activity


Make Your Own Rubin Voices Trading Card