Robert Hatch

SUBTOPICS:

1. The discovery of the galaxies
2. The expansion of the universe
3. Women’s contributions to American Astronomy
4. False data in science–scientific fraud

OBJECTIVES:

The students will:

1. understand and explain how the distance to nearby stars can be measured by the parallax method.
2. understand and explain how variable stars provided a key to locating the distance of astronomical objects
3. discuss the role of women in the history of American astronomy
4. discuss the importance of intuition in astronomy
5. discuss the problem of “scientific fraud”
6. form their own opinions of the importance of Harlow Shapley and Edwin Hubble in the history of astronomy
7. understand and explain the Doppler shift and especially the significance of the red-shift

Background Information

In the 1920’s, the size of the known universe increased by a factor of 100 billion and just a few years later came the discovery that the universe was expanding. The story of how these discoveries were made is one of the most exciting in the history of science.

Although this period in history included such obstacles as American women overcoming the rankest kind of discrimination to make important contributions and astronomers being held back by faulty data (or possibly even scientific fraud), two great discoveries were made: 1) the so-called nebulae (cloudy patches in the sky) were external galaxies, and 2) the universe was expanding.

ACTIVITY #1:

Discussion Class

            1-2 class periods

MATERIALS:

THE EXPANSION OF THE UNIVERSE HANDOUT (INCLUDED); SLIDES OF NEARBY GALAXIES (M31 AND M33), GLOBULAR CLUSTERS, AND ASTRONOMICAL OBJECTS; SLIDES OF THE MAJOR PERSONALITIES DISCUSSED IN QUESTIONS BELOW.

PROCEDURE:

1. FOR ADVANCED CLASS: Distribute the handout as a reading assignment and inform the students that a discussion on the questions below will take place the following day. On the next day, present the slides as the discussion progresses.
2. FOR REGULAR CLASS: Summarize the reading material in a lecture discussion format, presenting the slides as you progress (this will probably take 2 lectures).

   **You may wish to distribute these questions before or during the discussion.

   1. What was the difference between Kant’s and LaPlace’s models of the universe?
   2. Who was Annie Jump Cannon? Why did it take Harvard so long to recognize her accomplishments? Does discrimination against women in the sciences still exist?
   3. Explain how cepheid variable stars provided a way of measuring the distance to stars or star clouds. Who made this discovery?
   4. What was Harlow Shapley’s “intuitive leap?” What was Shapley’s chief contribution to astronomy?
   5. Did Shapley make a mistake when he left Mt. Wilson and took a job at Harvard? Explain your answer.
   6. Why was Shapley unconvinced by critics of his ideas?
   7. What was the significance of Adriaan Van Maanen’s data? Was it possible that he was engaged in scientific fraud?
   8. How did Hubble prove that M33 and the Andromeda nebulae were external galaxies?
   9. What did Hubble mean when he scrawled “Var!” on a photographic plate of the Andromeda nebulae?
   10. Can you think of any other explanation for the red shift other than the expansion of the universe?
   11. Describe the career of Milton Humason. Can you draw any lessons from that career?
   12. In your opinion, who made more important astronomical discoveries?
       1. Edwin Hubble or Johannes Kepler
       2. Edwin Hubble or Tycho Brahe

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   ACTIVITY #2:

   Demonstrating Parallax

              30 minutes

   PROCEDURE:

   1. Ask students to extend one arm and raise index finger on the hand of the extended arm.
   2. Have students look at the fingers and a more distant object in the room with one eye.
   3. Repeat the experiment with the other eye. The fingers will appear to have moved relative to the distant object.
   4. Students can calculate the distance to the finger triangulation by using their eyes as a baseline. The same principle applies to measuring the distance to nearby stars, using the earth’s orbit ½ way around the sun as the baseline.

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   ACTIVITY #3:

   Demonstrating the Doppler Effect

               30 minutes

   PROCEDURE:

   1. Take your class outside after school or during a break.
   2. Have one of the students who owns a car drive by the group while blowing the car’s horn. The pitch of the horn will drop noticeably when the car passes the group. This is the Doppler shift in sound which is analogous to the red shift in light.
   3. A second alternative demonstration would be simply to twirl a buzzer overhead in the classroom.

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   ACTIVITY #4:

   The Hubble Space Telescope

               30 minutes

   PROCEDURE:

   1. Remind students that Shapley and Hubble were both using powerful new telescopes.
   2. Ask one student (or a group of students) to report on the extent to which discoveries by Shapley and Hubble were dependent on their access to new instruments.
   3. Ask another student (or group of students) to report on the new Hubble telescope. For example:
      1. How well (or not so well) is the telescope working?
      2. Can it be fixed?
      3. Do you think it will ever provide the new discoveries once promised?

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   Bibliography

   Asimov, Isaac. The Universe.

   Ferris, Timothy. Growing Up in the Milky Way.

   Shapley, Harlow. Autobiography.

   Videotapes

   Cosmos. Dir. Carl Sagan. Episode 9, “The Life of Stars.” Episode 10, “The Edge of Forever.” Turner Home Entertainment.