Question: What is a radio telescope?

Derek McKay-Bukowski answered on 14 Jun 2011:

A telescope is a scientific instrument. It make small, faint, distant objects easier to see.

Normally, when most people think of telescopes, they think of optical telescopes. These are telescopes that work with light. They take the light from, say, a distant planet, and concentrate it to make the image appear bigger and brighter, thus allowing us to see more detail.

Some things give off light. Either they make their own light (such as a star) or they reflect it (such as our moon). But some things in space can also give off radio waves.

Radio telescopes make these fa. Let’s imagine you have an FM-radio. It can ‘hear’ the radio station, but only because the radio station is very strong and nearby. The FM-radio cannot tell which way it is to the radio station either. Now, with a radio telescope, you can hear extremely faint signals… not just radio stations, but the natural radio waves given off by the sun, the planets and galaxies – even natural radio waves from our own atmosphere! Additionally, the telescopes can work out exactly where the radio waves are coming from. That makes them very useful for understanding how the universe works (and for detecting things that would otherwise be invisible!)

There are lots of different types of radio telescopes. Some radio telescopes are huge metal dishes. Others are made of fields of wire aerials. Others still look like huge black solar panels.