What Is A Radio Telescope?

A radio telescope is a telescope thatuse antennas collecting signals instead of light to see objects distant in space. They are more powerful that optical telescopes and can be used to see objects which are too far away to view using light.

A typical radio telescope are made of dishes with movable antenna, and these collect the signals. Signals collected can be 100 million years old when they are collected here on earth.

The Arecibo dish is the largest radio telescope in the world and lives in Puerto Rico. Its build into a natural valley and has a diameter of 305 metres allowing even the faintest signals to be detected.

The first telescope was invented in 1608 by a Dutch optician called Hans Lippershcy. Before that, even as far back as the 13th century, scientists had been experimenting with magnifying lenses. Poor Lippershey was refused a patent for his invention, and the famous Italian astronomer, Galileo, hearing about this new idea, built his first telescope in 1609 and took all the credit for the wonderful new invention. It was a crude instrument; in fact, his most powerful telescope only magnified objects thirty-three times, and one could only see a small area (less than a quarter of the moon) at a time. Nevertheless, Galileo made some outstanding discoveries—he was the first to see the rings of Saturn, four of the satellites of Jupiter and the mountains and craters of the moon. Today, the principle behind Galileo's telescope is used for opera glasses, because it does not matter about their restricted vision and small magnification.

But telescopes have advanced beyond recognition since the time of Galileo and, with the coming of electronics, the radio telescope was invented. The radio telescope was developed after the Second World War it is a sort of giant "eye" that sees by radio waves sent out from the stars, in just the same way as we see their light waves. The "mirror" of the telescope is a huge saucer-shaped radio reflector many feet in diameter, and it has enormous advantages over an ordinary telescope because it can tune in on stars and galaxies that give no light at all, or such a faint light that it is not visible to an optical telescope. The radio telescope can also penetrate clouds of cosmic dust and gas that fill vast regions of space and the great thing is that scientists can use it in all weathers because radio waves have no difficulty in traveling through the cloud of the earth's atmosphere.

The largest radio telescope that can be pointed anywhere in the sky is at Jodrell Bank in Cheshire. The bowl is 76 meters across, and you can get a good view of it from the London/Manchester train.