Messages From ET: Part One

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In our last column we looked at the format of a message from a hypothetical ET. This message was designed in 1962 by astronomer Frank Drake after an early SETI conference in Green Bank, West Virginia. The message started out as a string of binary digits1s and 0s.

When reconstructed into a rectangle of black and white squares, it looks like this.  The circled numbers (1 through 5) have been added to help label the parts of the message.

All graphics by Ly Ly/SETI Institute

To try your hand at decoding the message, it may help to know that Drake encoded numbers and pictures to tell us about an imaginary civilization from another star system. To check the accuracy of your own interpretation, see the explanation for each of the major sections below.

1. A hypothetical solar system is shown, with the star at the top, and nine planets lined up underneath.

2. Two chemical elements critical for life on Earth are carbon and oxygen. Apparently, the same holds true for this fictional ET biochemistry. The central nucleus of each atom is shown with four black squares. The carbon atom (on the left) has six electrons circling its nucleus, while the oxygen atom (on the right) has eight electrons.

3. The numbers from one to five, written in a binary notation. This section of the message provides the foundation for understanding the numbers elsewhere in the message.

4. The population of three of the planets, written in a binary number system. Each number is located on the same row as one of the planets. The second planet from their star has a population of 5 - perhaps the crew of a small expedition. The third planet has about 2,000 inhabitants - possibly indicating the establishment of a permanent colony on this planet. The fourth planet, with a population of about 4 billion, seems to be the home world of this species.

5. Although the legs of this hypothetical ET are more splayed than we are used to seeing on humans, its general bipedal form is quite similar to our own. The number 31 is shown between brackets, indicating the height of the ET. But in what units? The key is in the signal itself. The wavelength of the radio signal, about 10 centimeters, is used as the basic unit of measurement. Thus, the ET is about ten feet tall. Underneath the ET is its name: "Four Bits" for short. Whereas all the numbers have an odd number of bits, this name has an even number, setting it apart as distinct. A line connects the image at the bottom of the message with the numbers above.