As you know now, in radio astronomy we study objects in the sky by catching radio waves. But what does that exactly mean? And what do radio astronomers see when they look at the sky? We will tell you all about that here.
Different types of radiation
You know now that there are different types of radiation which can be seen at different frequencies. Each radiation can be seen with different types of telescopes. Radio astronomers can look at different elements depending on the wavelengths they attempt to receive. If they study the same objects using different wavelengths, they will obtain images very different one from another, allowing different analyses.
In the image below you can see the different types of radiation (© NASA).
In the picture below, you see the Crab Nevel in different types of radiation. The Crab Nevel exploded 1000 years ago as a supernova. This was observed by the Chinese and was one of the first reports of a supernova. This nebula is about 6500 lightyears from Earth. As you can see the shape of the nebula is different in each type of radiation. You can also see different types of structures in the nebula. This gives us a lot of information about what is in the nebula.
Some galaxies were discovered in radio light first, such as Cygnus A (in the constellation of Swan, the strongest radio source, and one of the strongest sources in the sky). At high frequencies, we see a small dot in the middle, with two huge rays that end in some kind of dumbbell. This is not light as it is made in the sun (nuclear fusion), but light that arises because matter moves enormously fast in a magnetic field. This intensity can only occur if there is a black hole at the base.