Pioneer plaque

The Pioneer plaque is an engraved aluminum plate carried by Pioneer 10 and Pioneer 11. It depicts human figures, the spacecraft, and symbols intended to convey information about Earth and its inhabitants.

Hydrogen line: The 21-centimeter radio emission produced when neutral hydrogen atoms change their electron spin alignment. Its wavelength and frequency provide the plaque’s proposed universal units of length and time.
Pioneer 10: A NASA spacecraft launched in 1972 that became the first probe to fly past Jupiter. It carried the first copy of the plaque beyond Earth.
Carl Sagan: An American astronomer and science communicator who helped popularize planetary science and the search for extraterrestrial life. Sagan proposed adding a message to the Pioneer spacecraft and helped develop the plaque.
Voyager Golden Record: A collection of sounds, images, and greetings placed aboard the Voyager spacecraft in 1977. It expanded the Pioneer plaque’s idea into a longer, more varied message.
Pulsar: A rapidly rotating neutron star whose beams of radiation produce regular pulses detected from Earth. Pulsar directions and periods encode the Sun’s position in the Milky Way.
Pioneer 11: A NASA spacecraft launched in 1973 that flew past Jupiter and Saturn. It carried the second copy on a separate route through the outer Solar System.
Frank Drake: An American astronomer who developed the Drake equation and helped pioneer the search for extraterrestrial intelligence. Drake designed the pulsar map and contributed to the plaque’s scientific encoding.
Arecibo message: A 1974 radio transmission from the Arecibo Observatory containing encoded information about humanity and Earth. It reused some plaque motifs in a message deliberately sent toward a star cluster.
Astronomical unit: The conventional unit of length based on the mean distance between Earth and the Sun. The spacecraft outline uses this familiar solar-system scale to suggest its size.
Human figure: A visual representation of a human being, often used to communicate anatomy or identity. The plaque’s male and female figures attempt to show the bodies of its makers.

Linked from 6 pages