The Big Ear radio telescope was built in 1963 to survey the sky for extragalactic radio sources. It is a type of radio telescope that uses the rotation of the Earth to make observations. The receiver of the radio telescope can be moved north or south, but to view things east and west you have to wait for the Earth to rotate in the right direction. This type of telescope is perfect for making sky surveys, because you can point it in a particular declination (the sky version of latitude), and then let the Earth’s motion move you through a full circle of sky over the course of a day.
A few days ago I wrote about an interesting type radio signal known as a fast radio burst. These are short, intense pulses of radio energy that have all the hallmarks of being astronomical in origin. One possible source of FRBs could be a neutron star collapsing to a black hole. But there is still some discussion that such bursts could be terrestrial in origin because of another type of radio burst known as a peryton.
Radio signals from pulsars are delayed slightly by the ionized plasma in our galaxy. This allows us to measure the amount of plasma in our galaxy by observing the pulses of more than 2000 pulsars in our galaxy.
When radio waves travel through the ionosphere, lower frequency waves travel more slowly than higher frequency ones. This can create an effect with radio signals known as whistlers.