Pulsars are one of the finest tools we have for testing Einstein’s theory of general relativity.
CSIRO Parkes radio telescope has discovered around half of all known pulsars. Credit: Wayne England, Author provided
A pulsar is a small, spinning star – a giant ball of neutrons, left behind after a normal star has died in a fiery explosion.
With a diameter of only 30 km, the star spins up to hundreds of times a second, while sending out a beam of radio waves (and sometimes other radiation, such as X-rays). When the beam is pointed in our direction and into our telescopes, we see a pulse.
2017 marks 50 years since pulsars were discovered. In that time, we have found more than 2,600 pulsars (mostly in the Milky Way), and used them to hunt for low-frequency gravitational waves, to determine the structure of our galaxy and to test the general theory of relativity.
In mid-1967, when thousands of people were enjoying the summer of love, a young PhD student at the University of Cambridge in the UK was helping to build a telescope.
It was a poles-and-wires affair – what astronomers call a “dipole array”. It covered a ...