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Guide Index

How Did the Universe Begin?

Where Did Life Come From?

How Did Earth Get Animals?

Are We Alone?

Will Robots Take Over?
in the classroom


With billions of galaxies in our universe, is it possible that life exists outside our solar system? Alan Alda talks with Carl Sagan about the possibility of finding life elsewhere. Then Frontiers visits Paul Horowitz, a scientist who's searching for signals of intelligent life. We also visit NASA scientist Jack Farmer, who is looking for simple forms of extraterrestrial life. We join Jack Farmer as he rehearses for a Mars mission that will look for fossils of past life.

Curriculum Links
Activity: Send a Message Into Space



radio astronomy

coacervates (pre-cells)

moneran kingdom

solar systems,


minerals, solutions

radio wave distances

radio waves

satellite dishes


Imagine that you have been put in charge of sending a message to an extraterrestrial civilization. Your message should tell the receiver all about the earth and its inhabitants. All of the information is to be placed on a phonograph record limited to one hour of playing time on each side ... and you are given six weeks to produce the record.

This was the challenge presented to astronomer Carl Sagan in the summer of 1977 as the two Voyager spacecraft were prepared for launch. Experts from NASA, government officials, business executives, science educators and many others worked together to produce a gold-covered, copper record containing photographs, music, greetings in 55 languages and sounds believed to represent the planet Earth and life on Earth. One copy of the record (plus a cartridge, stylus and pictorial instructions for playing it) was sent into space on each of the Voyager spacecraft, which have now left our solar system.

The most difficult part of making the record was selecting just the right material to help others learn what life on Earth is like. Typical questions for the group may have been: Which photos, songs or sounds are most representative of the diversity of life on Earth? How would you identify universal themes so they can be understood by alien life-forms?

  • blank cassette tape and tape recorder
  • blank videotape and video camcorder
  • computers
  • crayons, markers, colored pencils
  • envelopes
  • magazines
  • boxes or other containers
  • poster paper

* Suggested materials only. This activity can be simple or complex, depending on materials available.


In this activity, you will work in small groups to create a message. You will use a variety of materials to communicate to others what it is like to be a teenage earthling. Your message may be arranged in any order. Be as imaginative, creative and accurate as you can. Your only limitation is that you may not use written words. Decide on your message, but do not share it with any other groups!

Each group should place its message in a box or container. Taped to the box or container will be a sealed, detailed letter of explanation about the message.

Each box will then be exchanged and each group will attempt to interpret the message they have received. Do not open the sealed messages yet!

Each group should write an interpretation of the other messages. When finished, open the sealed envelopes and compare these messages with interpretations.

  1. How did you decide what to include in your message?

  2. Was your message understood? If not, why do you think it was misinterpreted?

  3. What seemed to be the most difficult concept to communicate?

  4. How could you improve your message?

  5. Would people from other countries understand your message? Why or why not?

  • How would you warn future beings about such hazards as toxic waste sites? What messages would you want to send and how would you communicate them?

  • Project Star at Harvard offers many ideas for astronomy projects, including a kit to build a telescope. Write to Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138.

  • Murmurs of the Earth, a CD-ROM of the Voyager Interstellar Message is available from Time Warner Interactive. Call 1-800-593-6334 for information.


Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.