The Little Green Men

The Little Green Man is 50 years old today!  On this day in 1967 astronomer Jocelyn Burnell Bell found an unusual object blinking in a dark corner of the sky in the constellation Vulpecula. With a period of 1.3373 seconds and a pulse width of 0.04 second it was the first radio pulsar discovered, although Bell and her Ph.D. advisor astronomer Antony Hewish had no idea what exactly they were seeing. Given the regularity of the signal, they briefly (and mostly jokingly) considered the possibility that they had stumbled upon evidence of extra-terrestrial intelligence, and dubbed it LGM1, for Little Green Men 1. According to Bell:

We did not really believe that we had picked up signals from another civilization, but obviously the idea had crossed our minds and we had no proof that it was an entirely natural radio emission. It is an interesting problem - if one thinks one may have detected life elsewhere in the universe how does one announce the results responsibly? Who does one tell first?

Thomas Gold and Franco Pacini suggested that pulsars were in fact pulsating neutron stars, confirmed with the discovery of a second pulsar in the Crab Nebula. The next year in March 1968, The Daily Telegraph was first to publish the new word:

An entirely novel kind of star came to light on Aug. 6 last year and was referred to, by astronomers, as LGM (Little Green Men). Now it is thought to be a novel type between a white dwarf and a neutron [sic]. The name Pulsar is likely to be given to it. Dr. A. Hewish told me yesterday: “… I am sure that today every radio telescope is looking at the Pulsars.”

The word itself was a combination of pulsating and star, a very literal and descriptive explanation of what scientists were seeing. Today that first pulsar is known variously as CP 1919, PSR B1919+21 and PSR J1921+2153.

Pulsars are so unique that NASA used them as intergalactic locators, drawing a map on the Pioneer plaques to allow extra-terrestrial intelligences to find planet Earth.

In 1974 Antony Hewish became the first astronomer to win a Nobel Prize in Physics, with a bit of controversy surrounding the award as Bell (who actually discovered the pulsar) was not co-awarded the prize.

All images used under CC 3.0 license.