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Teez
2003-Mar-26, 05:34 PM
I have a question regarding the plaque on Pioneer 10 (http://www-pw.physics.uiowa.edu/pioneer/other/plaque.gif). What is the significance of the binary equivalent of the decimal 8 on it? Likewise, why did they put a symbol for the "hyperfine transition of neutral hydrogen"? TIA!

ToSeek
2003-Mar-26, 07:12 PM
The "hyperfine transition of neutral hydrogen" provides a standard for both length (21 cm) and time (~1.4 nanoseconds). The binary 8 indicates that humans are around 8*21 cm tall, while the time periods are used for the pulsar timings in the "starburst" image on the left.

This page (http://www.enterprisemission.com/pioneer.html) is hosted by noted fruitcake Richard Hoagland but includes links to the scanned pages of Carl Sagan's article on the plaque in Science magazine, with a full explanation of all the features.