“We [are] a species endowed with hope and perseverance, at least a little intelligence, substantial generosity and a palpable zest to make contact with the cosmos.” -Carl Sagan
When the Voyager and Pioneer spacecraft were launched, they contained a message emblazoned on them: a map of 14 pulsars, showing the location of Earth relative to them. This was a brilliant idea: showcase bright, unique identifiers, complete with their observed periods and distances from our world, and people would be able to find Earth. If we wanted to be found, it was the best idea 1977 had to offer.
But 40 years later, the idea is fundamentally flawed. There are up to a billion pulsars in the Milky Way, their periods change long-term, and their orientations are variable over time, meaning they won’t be pointing at Earth in the future. If we wanted to be detected, we’d be much better off sending the same information we use to detect exoplanetary systems today!
Although it was a very clever idea presented just 10 years after the discovery of pulsars, we now know that Voyager’s cosmic map to find Earth will be hopelessly wrong by the time an alien civilization finds it.