The First Pulsar Was Nicknamed LGM-1 — 'Little Green Men' — for a Reason
Answers: “what is a pulsar?”
In 1967, a 24-year-old PhD student named Jocelyn Bell was reviewing data from a radio telescope she’d helped build — kilometers of chart paper, analyzed by eye — when she noticed a “bit of scruff.”
The scruff turned out to be a radio signal pulsing every 1.3373 seconds, with precision rivaling an atomic clock. Nothing natural was known to tick like that. Half-jokingly, the team catalogued it as LGM-1: Little Green Men 1. For a few weeks, the possibility that they’d intercepted an alien beacon was discussed seriously — Bell later recalled being annoyed that aliens might derail her thesis.
Then she found a second pulsing source, in a completely different part of the sky. Two separate alien civilizations using identical beacons was too much coincidence. This was a new kind of star.
They’re called pulsars now, and the reality is spectacular: a pulsar is a spinning neutron star — a dead sun crushed to city size — with beams of radiation firing from its magnetic poles. If a beam happens to sweep across Earth, we see a pulse. A cosmic lighthouse.
The extremes are hard to overstate:
- Some pulsars spin hundreds of times per second — surface moving at a noticeable fraction of light speed
- The fastest known, PSR J1748-2446ad, rotates 716 times every second
- Millisecond pulsars keep time so well they rival atomic clocks over decades — astronomers use networks of them as a galaxy-sized gravitational wave detector
- The pulsar map engraved on the Pioneer and Voyager probes uses 14 of them as GPS satellites for finding Earth
The 1974 Nobel Prize went to Bell’s supervisor. Bell herself was omitted — one of science’s most cited injustices, which she has handled with famous grace, later donating a $3 million prize to fund underrepresented physics students.
The universe’s most precise clocks are corpses. And a student found the first one by refusing to ignore a smudge.