How do we know that? Seeing with radio waves!

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Hello again, in previous months talking about astronomy, I've talked about how we know the distances of stars etc. This months how do we know that, is a little different.

Astronomy is a very ancient science, but for thousands of years it relied on what people could see, firstly with only their eyes, and then starting with Galileo using telescopes. Taking measurements and developing maths to use those measurements taught us a lot, thank you Isaac Newton.
In the 1800s it was realised that the light we see with has other frequencies that we can't see, such as infra red and ultra violet and gradually we understood that light was part of what's called the electromagnetic spectrum. Radio waves, gamma rays, x rays and loads more are all part of this.
Astronomers found all these discoveries in science fascinating, and began to wonder what it would be like to see with radio waves. This really began in the 1930s when a telephone engineer, Karl Jansky couldn't find the cause of radio noise in his equipment, at first he thought it was from the sun, but an astronomer friend realised it was from the constellation Sagittarius. This was happening only a few years after the discovery of the nature of galaxies by Edwin Hubble who the space telescope is named after. The radio interference, it was realised was from the centre of our galaxy so that is how we know where the centre of our galaxy is. This is something no one will ever be able to see with our eyes, all the dust between us and the centre blocks the light, but radio waves etc can reach us through the mire. It's a bit like being able to hear your radio on a foggy day.
The second world war began not long after all that, and massive advances were made with radio equipment and what radio waves do, but everything discovered was a secret. In the 1950s several groups such as the Mullard radio astronomy group were set up and the real dawn of modern astronomy began and observations flooded in, a radio map of the sky was initiated and things got very complicated very quickly. The maths needed was huge especially with what's called Fourier transforms which I'm not even going to attempt to explain, Google it if you're interested. Fortunately this was also the beginning of the computer age and early computers like Titan made progress possible.
Learning about a whole new astronomy and finding objects with radio waves that we never even suspected would exist has been going on for only about 70 years so whilst we now know that a radio universe is very different to what we see with our eyes there is bound to be a whole lot more to come.

Charles Oates, Vega Baja Astronomy Group.

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