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STARSStories

2 March 1972

A map of pulsars on a machine leaving home

Pioneer 10 carries a gold plate. The sky on it is not a pretty dipper. It is a set of clocks, so that someone else could find the Sun.

Cape Canaveral, then Jupiter and beyond

OBJECTThe Pioneer plaque is a physical object on the spacecraft. This page is not a photograph of the plaque. We do not redraw it here.

The plate

Pioneer 10 leaves Earth for Jupiter, then the long dark. On it, a gold-anodized plate: two humans, a hydrogen atom, and a burst of lines. Each line is a pulsar. The lengths are periods. Together they point back to the Sun at a date, because pulsar clocks slow, and the slowing is a timestamp.

Sagan, Drake, Linda Salzman Sagan. A committee of three, not a lone poet. The sky on the plate is a tool. The stars, as pulsars, are how you would know where this machine came from.

ASTRONOMY

Pulsars are rotating neutron stars. Bell Burnell’s 1967 discovery is the condition for this map. Without timed dead stars, there is no such return address. The plaque is not a proof that we were found. It is a decision about what a star is for, once you can leave.

Question

What kind of map is a set of dying clocks?

Sources

Also this sky