Seeing the Universe

before 1610 - naked eye astronomy

1608 - Galileo's hand held telescopes

1780 - Herschel's large reflectors

1838 - Meridian Circles

1845 - Rosse's Leviathian

1890 - Barnard's camera

1923 - The Hooker 100 inch

1948 - The Palomar 200 inch

1990 - The Hubble Space Telescope

1998 - The Keck 10 metre pair

2000 - The VLT array

2015 - Planning for the JWST

2020? - Planning the OWL

How much further?

When astronomers tried to make high magnification telescopes they were thwarted by the dispersion of light that occurs in simple lenses. High curvature lenses form images marred by coloured fringes - the chromatic abberation effect. Telescope makers found they could minimise the effect and obtain high magnifications by making instruments longer. Around 1673, in a quest to obtain better views of the universe Hevelius made a series of instruments up to 42 metres long. One of the smaller scopes, 6 metres long, is shown here. The longer scopes were almost impossible to use due to the difficulty of keeping their lenses in line. It was difficult to align them accurately on targets as well, for their mountings were crude - the tube was simply suspended from a pole by ropes. Hevelius did his main work, compiling a catalogue of the positions of 1,500 stars, without telescopes.

The invention of the achromatic lens eventually solved the colour fringe problem and enabled refracting telescopes of more manageble lengths to be built. Over time, a range of precisely engineered mounting arrangements were also developed.  Early Telescopes