Perseids

Last night and tonight the meteor shower known as the Perseids will be in full spate, as the Earth makes its regular passage through the dust cloud of meteorite particles from the tail of the comet Swift-Tuttle. In ideal conditions in the pre-dawn of the 12th and 13th, an observer might expect to see 100 meteorites per hour. Ideal conditions never pertain, but it is, at its best, a dramatic sight.

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Astronomy at Cambridge has a prestigious history. The first astronomical observatory in the university was built at the top of Trinity College gatehouse in 1704 in the time of Newton, but astronomy had been a cornerstone of the medieval quadrivium from the foundation of the university in the thirteenth century. In the century before Newton, Jeremiah Horrocks demonstrated the elliptical orbit of the moon (in 1639) and made the first observations of the transit of Venus. By the age of 22, while still an undergraduate, Issac Newton had unified celestial mechanics with those of his nascent theory of gravity (derived in part from Kepler’s third law of planetary motion).

In the twentieth century, Cambridge was the university of several very notable astronomers: the great (and controversial) Fred Hoyle, for example, who predicted that heavy elements, specifically carbon, could be generated within stars; or Arthur Eddington, who between 1915 and 1926 derived equations which explained the structure and evolution of stars for the first time; and it was at Cambridge that pulsars (collapsed neutron stars) were first identified in 1967 by Tony Hewish and Jocelyn Bell.

Cmglee_AMI_Large_Array_telescopeThere is a pair of optical telescopes on the site of the Cambridge Observatories (the first of which was founded in 1823) to the west of the town along the Madingley Road. The telescopes are small and affected by light pollution, but are still in use. More significant is the site a few kilometres to the south west, towards Coton, where a series of radio telescopes known as the Mullard Radio Astronomy Observatory (which includes the so-called One-Mile Telescope, the world’s first fully steerable radio telescope) form a variety of arrays directed to the study of  background radiation and galactic clusters.

So, as you lie back in your deckchair with your thermos in the pre-dawn, watching the odd fragment of cosmic dust fizzle up in the atmosphere, you can reflect that you are watching from an exalted patch of ground. Astronomy is not just a bucket of information about the stars, after all; it is also history of our hard-won understanding of the stars, and much of that history took place here in Cambridge.

400px-One-Mile_Telescope

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