At lower frequencies our galaxy emits prodigious amounts of radio waves creating a loud background of noise. At higher frequencies the Earth’s atmosphere, and presumably the atmosphere of other ...

At double the width of our Milky Way galaxy, this jet of radio waves is the biggest ever detected ... because of the obscuring cosmic microwave background left over from the Big Bang.

So, instead of using ultrasound, radio waves are used as they travel at 300,000,000 m/s. It works in the same way as sonar but with radio waves in place of ultrasound. A short pulse of radio waves ...