In The Sky at Night on 24 November 1976, Patrick looked at quasars, cosmic objects that look like stars but behave very strangely.
They were discovered in 1963 when a radio source that had no obvious visible counterpart was matched with what at first appeared to be a faint blue star.
The following year, astronomers were able to take a spectra of quasar 3C 273 when it was occulted by the Moon. This showed the emissions lines were shifted by 15.8 per cent, one of the biggest shifts ever seen up to that point. If it was due to the motion of the object itself, it meant
