In 1977, astronomer Jerry Ehman was analyzing data from the Big Ear Radio Telescope in Ohio when he noticed something extraordinary — a 72-second radio signal unlike anything ever recorded. It came from the direction of the Sagittarius constellation, clear and powerful, at a frequency often linked to hydrogen — the building block of life. Astonished, Ehman circled the reading on the printout and scribbled one word in the margin: “Wow!” That single reaction gave the mysterious signal its now-famo