Sir Isaac Newton was born on 4 January 1643 at Woolsthorpe Manor House near Grantham, Lincolnshire. He was a mathematician, physicist, astronomer, theologian, and author who is widely recognised as one of the most influential scientists of all time and as a key figure in the scientific revolution. In the 1660s he observed that a prism dispersed white light into a spectrum of colours. From this work he concluded that any telescope using lenses (refracting telescope) would suffer from the same colour dispersion (chromatic aberration). He therefore constructed a telescope using reflective surfaces instead of lenses which did in fact solve the problem of chromatic aberration.
Celebrations for the tercentenary of Newton’s birth were put on hold because of the Second World War but in 1946 the President of the Royal Society announces funding for a 100-inch telescope for British astronomers to use. It was to be called the Isaac Newton telescope and would be sited at the Royal Greenwich Observatory (RGO) in Herstmonceux. The telescope would have 7 times the light-grasp of existing telescopes in Britain at the time (the two 36-inches) and would prevent a brain drain of practical astronomers to the US which was already much better endowed with large telescopes. The project was funded jointly by the Treasury and the Admiralty and a committee of the Royal Society was set up to progress the building of the telescope. It was RGO staff, however, who were to subsequently maintain and operate the telescope.
The biggest part of a telescope such as the INT is the main mirror, called the primary, and here the project got off to a good start. In 1949 an American charity offered Spencer Jones, Astronomer Royal at the time, a spare Pyrex disc suitable for the telescope for free. It had been cast in 1936 by the same firm that made the 200 inch mirror for Palomar (Corning Glass Works) and had been intended for a telescope in Michigan that was never built. The 5 tonne disk was brought to Britain and Spencer Jones was thereafter known as Scrounger-Jones in some US circles – according to Fred Hoyle.
For reasons hard to explain nothing happened for many years. Maybe it was because the project was in the hands of a committee – Spencer Jones could not be seen to be trying to take it over. They argued endlessly about what sort of telescope it was to be and at one stage the money was withdrawn.
When Richard Woolley became Astronomer Royal he took the project by the scruff of the neck. In 1959 Howard Grubb, Parsons and Company in Newcastle-upon-Tyne were commissioned to design and construct the telescope and immediately set about grinding the mirror. It took more than a year for this process and 1,800 lb (816 kg) of pulverised glass was discarded. There were problems in the process due to cracking and crazing of the mirror which had to be filled with araldite to stabilize it for polishing.
In 1965 the telescope saw ‘first light.’ In 1967 the Queen came to Herstmonceux to inaugurate the telescope. It was hoped she would look at Saturn through it, but it rained – no doubt reinforcing the views of all those who were wondering about the wisdom of building a world-class telescope in lowland Sussex, a decision that was 50% politics.
At the time the giant dome was in open countryside. Richard Woolley commissioned the planting of the trees that now surround the dome.
Weight: 9,000 lb (4082 Kg)
Diameter of the primary mirror: 98.2 inches (2.5 metres)
Thickness of the primary mirror:16.1 inches (41 cm)
Prime focus: f/3 (observer rides in a capsule in the mouth of the telescope)
Cassegrain focus: f/14.1 (observer rides in a chair slung below the mirror)
Coudé focus: f/32.3 (observer at a fixed focus one floor below the telescope)
The telescope was placed on a platform 48 feet high to raise it above the surrounding mists. The telescope was kept at the prevailing night temperature during the day whatever the season so that convective air currents didn’t disturb star images.
There was a heated control room so the astronomers didn’t freeze half to death in the winter. The model of Isaac Newton’s original telescope was set up alongside the main telescope in a glass case, and someone with a sense of humour added a note at the bottom
“When main telescope fails, break glass.”
For more information see the section on Scientific Achievements. However, here are just some of the projects carried out using the INT.
Proper motions of stars: Actual velocities and directions. This indicates where stars were formed and helps to elucidate the evolution of the galaxy.
Quasars (QUASI STELLAR RADIO SOURCE): these are powerfully energetic, very distant sources of light (an ACTIVE GALACTIC NUCLEUS).
Black holes: Professor Donald Lynden-Bell predicted that black holes existed in the centre of galaxies. Herstmonceux was very much involved with the discovery of the first black hole, even if it wasn’t the same type as that predicted by Lynden-Bell.
The question of whether or not it was sensible to put such a big telescope at a limited site was asked before it was built, and more and more openly afterwards. The answer refers back to the politics of the project. It was the Isaac Newton telescope, it couldn’t be anywhere else than in Britain; there was no other option. Woolley probably believed that even if the telescope was not fully justified here, it was a stepping stone to get good British telescopes at better sites abroad, and so it turned out to be.
In the late 1960s a concept was developing for a Northern Hemisphere Observatory. This led to a project for the founding of an international observatory in the Canary Islands. Although the INT itself was acquitting itself at Herstmonceux, the weather at the site was not ideal.
With the advent of mass air travel it was plausible for UK astronomers to run an overseas observatory. In 1979, the INT was shipped to the top of the mountain at Roque de los Muchachos Observatory on the island of La Palma where it continues working to this day. It saw its second first light in 1984, with a video camera. A major change was the mirror. The original Pyrex mirror was replaced by a larger 100 inch (2.54 metre) one made of a new type of glass; Zerodur glass.
Today, it is used mostly with the Wide Field Camera (WFC), a four CCD instrument with a field of view of 0.56×0.56 square degrees which was commissioned in 1997. The other main instrument available at the INT is the Intermediate Dispersion Spectrograph (IDS), recently re-introduced having been unavailable for a period of several years.
Dismantling the INT in the late 1970s was the beginning of the end for Herstmonceux. With the telescope transferred to La Palma there was little cause for keeping the estate on. Astronomy was changing. With cheap air travel astronomers could work in little offices anywhere and jet off to the big mountaintop observatories around the world for their observing sessions.
So with much heartache and recrimination Herstmonceux closed in 1990, a sad end to the all-too-brief Golden Age of Astronomy at Herstmonceux. The remnants of the observatory moved to an office block in Cambridge, and finally, in 1998 it closed altogether as an observing establishment, after 323 years.