Are you thinking of a "quasar" ?
Radio waves travel at the speed of light, so radio waves broadcast 100 years ago that were strong enough to reach into space are 100 light-years away.
The question is too vague for an answer. It depends on the intensity of the radio wave source.
usten were coming home
You can get a radio signal from space on your computer using SETI.
We are listening with radio telescopes for radio signals from space, that sound as if they might come from an intelligent source (i.e., modulated, like a fax machine over a telephone)
radio astronomy
radio astronomy...:)
There are various objects that can be responsible for radio emissions in space. These objects are referred to as astronomical radio sources.
A space word that starts with z is Zaurak.
A radio telescope.
orbit
with radio waves