Telescopes are astronomy's most important tool. Without them our picture of the Universe would be dramatically less rich and detailed.
There are many different types of telescope. Traditional ones gather visible light from distant objects to produce a magnified image. It was this kind of instrument that was first pointed skywards by the Englishman Thomas Harriot and later put to famous use by Galileo Galilei.
Image: A telescope made by Isaac Newton on display at The Royal Society
Astronomy's most important tool continues to evolve.
Mark Thompson shows Jonathan Ross how to find the basic constellations.
Mark Thompson shows Jonathan Ross how to find the basic constellations in the night sky, starting with the Plough and the Pole Star.
Mark Thompson's guide to photographing the night sky.
Expert astronomer Mark Thompson shows you how to get started in photographing the night sky. Learn how easy it is to capture images of space in your own back garden without using expensive kit.
Mark Thompson gives Jonathan Ross a telescope beginner's guide.
Astronomer Mark Thompson gives Jonathan Ross a telescope beginner's guide.
Patrick Moore looks at the William Herschel Telescope's mirror.
In 1987 Sir Patrick Moore gets a glimpse of the 4.2m mirror used in the William Herschel Telescope.
In 1987 Horizon reports on the William Herschel Telescope.
In 1987 Horizon reported on the William Herschel Telescope, which was built on La Palma in the Canary Islands.
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such as visible light). The first known practical telescopes were invented in the Netherlands at the beginning of the 17th century, using glass lenses. They found use in terrestrial applications and astronomy.
Within a few decades, the reflecting telescope was invented, which used mirrors. In the 20th century many new types of telescopes were invented, including radio telescopes in the 1930s and infrared telescopes in the 1960s. The word telescope now refers to a wide range of instruments detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors.
The word "telescope" (from the Greek τῆλε, tele "far" and σκοπεῖν, skopein "to look or see"; τηλεσκόπος, teleskopos "far-seeing") was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galilei's instruments presented at a banquet at the Accademia dei Lincei. In the Starry Messenger, Galileo had used the term "perspicillum".