The World's Biggest Telescope

The Birr Leviathon

<P> The great telescope had the biggest metal mirror ever cast: it measured 1.8 metres across and sat at the bottom of a wooden telescope tube that was over 16 metres long. The combined weight was 12 tonnes, and needed a complex system of counterweight, pulleys and chains to move it. </P> <P> Substantial walls were built to support and shelter the telescope and to hold the observing platforms and lifting mechanisms. Most of the work was done by local tradesmen, and the project probably cost several million euro in today's money. </P> <P> It remained the world's largest telescope until 1917, but its bulk made it hard to control and it was too clumsy to use with new instruments such as cameras, plus its location in Ireland's boggy midlands meant skies were seldom clear and the metal mirrors quickly tarnished. </P> <P> Birr telescope has been restored to working order, and the castle is open to the public. </P> <P> Pictured above is a sketch of the Birr Leviathon alongside that of the whirlpool nebula (as seen through it). </P>

Image: Courtesy of Offaly County Library
The Birr Leviathon
Image: Courtesy of Offaly County Library

The Birr Leviathon

<P> The great telescope had the biggest metal mirror ever cast: it measured 1.8 metres across and sat at the bottom of a wooden telescope tube that was over 16 metres long. The combined weight was 12 tonnes, and needed a complex system of counterweight, pulleys and chains to move it. </P> <P> Substantial walls were built to support and shelter the telescope and to hold the observing platforms and lifting mechanisms. Most of the work was done by local tradesmen, and the project probably cost several million euro in today's money. </P> <P> It remained the world's largest telescope until 1917, but its bulk made it hard to control and it was too clumsy to use with new instruments such as cameras, plus its location in Ireland's boggy midlands meant skies were seldom clear and the metal mirrors quickly tarnished. </P> <P> Birr telescope has been restored to working order, and the castle is open to the public. </P> <P> Pictured above is a sketch of the Birr Leviathon alongside that of the whirlpool nebula (as seen through it). </P>

Image: Courtesy of Offaly County Library
Enlarge image

The bigger the telescope, the more light it can collect, allowing astronomers to see further and to study fainter objects. Until 1845, the biggest telescope was at Greenwich Observatory in London, with a mirror measuring 124 cm across.

William Parsons, third Earl of Rosse, wanted to study faint fuzzy patches of light called nebulae, and spent years building an enormous telescope, his Leviathon. The Hubble space telescope of its day, it let astronomers see further into space than ever before.

As soon as it was ready, Parsons trained his telescope on a nebula known as M51, and saw it was a spiral cluster of stars, which he called the Whirlpool Nebula. The discovery caused a sensation, because it seemed to confirm that the Universe was fixed and unchanging. Today, we know that many nebulae are dust clouds and breeding grounds where new stars form, and that the Heavens can and do change.


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