TURN ON YOUR television, or your radio, and tune it to an empty station where you can’t receive any signal. See all those black and white dots scattering around the screen, or hear that faint hiss in the background? A part of that is a radio signal from the universe, namely the Cosmic Microwave Background radiation, the heat energy left over from the Big Bang itself.
Light at radio-wavelengths is emitted by all kinds of celestial bodies: stars, galaxies, planets, and more. Visible light that we use “normal” telescopes for only gives us part of the picture, whereas radio astronomy opens up an entire new spectrum of the universe we are otherwise blind to.
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