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A guide to the mysterious light of quasars
It was the 1960s and Maarten Schmidt faced an observation, unlike anything he’d seen before.
Quasars had been discovered at the end of the last decade as mysterious radio sources in all-sky radio surveys. Whilst Penzias and Wilson were busy evicting pigeons from their radio antenna, trying to find the origin of a mysterious omnipresent hum, these radio signals came from very small, particular locations in the sky.
Yet, there was something strange about them. Hundreds had been detected in the radio part of the spectrum but there didn’t seem to be an optical component.
What were these invisible objects emitting such intense radio waves?
Finally, Allan Sandage and Thomas Matthews identified an object in the sky that appeared to be in the same location as a radio source, imaginatively called 3C 48.
A faint blue light.
However, with every new discovery, nature has a way of introducing just as many new mysteries.
When an astronomer discovers an object emitting light, one of the first things they do is find out what wavelengths are contained within it, that appear as emission lines. Each line is a very specific wavelength of light created by a particular energy transition of an atom. Spotting these lines can reveal from what…
