66. COMETS

from Come Fly With Me – Exploring Science through aviation and aerospace concepts.

SUBJECT: Science
GRADE: 7,8,9
GROUP SIZE: Large
TIME: 60 minutes
TYPE OF ACTIVITY: Discussion Student Investigation
TEACHING STRATEGY: Open Discovery Guided Discovery
CONCEPTS: Comet Orbit Period
SKILLS: Reading for Information Interpreting Data

Objectives: To understand the structure of a comet; to understand comet orbits and periods.

Materials: Books, pamphlets, etc., on comets.
Teacher Background Information:

In 582 AD, Gregory of Tours wrote the following:

“. . . there were rains, lightnings and great thunderclaps in the month of January. Trees blossomed; the comet appeared in such a way that round about it there was a great blackness; it shone through the dark as if set in a cavity, glittering and spreading abroad its hair . . . And on the holy day of Easter, in the city of Soissons, men saw the heavens aflame, in such wise that there appeared two fires, the one greater, the other less. But after the space of two hours they were joined together, making a great beacon-light before they vanished away. In the territory of Paris there rained real blood from the clouds, falling upon the garments of many men, who were stained and spotted that they stripped themselves of their own clothing in horror.”

By the late 1600’s, due in large measure to astronomers like Tycho Brahe and Sir Edmund Halley, accounts of such destruction following in the wake of a comet sighting had become a great deal rarer. However, enthusiasm for comets has not waned (witness the recent movie “Comet” which brought celluloid disaster to the greater part of Arizona). The return of Halley‘s Comet in 1985 and 1986, provides an even greater interest in what comets are all about.

Because of the return visit, several European countries, the Soviet Union and Japan designed spacecraft to study Halley’s comet and, though the U.S. plan to design a craft specifically to study Halley was rejected, a satellite already in orbit was deflected to get some closer pictures of the comet as it passes by.
Procedure:

  1. Write the word COMET on the board and read the account written in 582 AD by Gregory of Tours. Discuss the passage and ask the students to relate what information they have on comets.
  2. As the students bring up information that is unclear or contradictory, work with them to formulate questions for them to find information on.

Some of the likely questions might be:

  • Just what are comets?
  • What are they made of?
  • Where do they come from?
  • How come some show up in regular periods of time?
  • Why are they called comets?
  • What comet(s) might we be able to see during the next few years?
  • How are comets named?
  • Why do they have a tail?
  • What happens when one hits the Earth?
  • What are the chances of that happening?
  • Should we be worried about that, too?!?

Once the students have generated questions, ask how they think they might find information that would help them to answer some of the questions. Talk about the possibilities – where to look, what to read, who to write or talk to. Divide the questions among the students and ask them to do some searching and to report back to the class in a way that is as exciting as watching a comet streak across the sky.
Data from “Comets,” Center for Astrophysics, Harvard Col. Observatory, Cambridge, MA 218

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