Planetary commotion

Nicholas Pyke

The discovery of Neptune 150 years ago resulted in a national scandal. This is a busy time for astronomers. Last Saturday saw the official end of National Astronomy Week. A few days before that, the insomniacs among us witnessed a lunar eclipse. Later on this month the moon gets its own back with a partial eclipse of the sun.

September is also the 150th anniversary of the discovery of the planet Neptune, only the second new planet to emerge since the ancients first mapped the solar system.

A triumph for European science? Perhaps. But for British astronomy the discovery of Neptune marked a humiliating failure and, according to the Royal Astronomical Society, proved to be one of the most controversial episodes in the history of British Science.

Mathematicians in this country had already predicted the existence of the new planet: yet it was left to the French and Germans to actually prove the case.

The embarrassment was all the greater for Britain's impressive record in astronomy up until 1846. Newton's theory of gravitation and Halley's use of it to predict the return of the comet that carries his name had done much to explain the physics of the heavens.

It was also a British astronomer, William Herschel, who discovered Uranus in 1781. Too far away to be seen with the naked eye, it had eluded Greek and Roman astronomers, but it couldn't elude the comparatively sophisticated telescopes of the 19th century, which helped map our solar system.

But when in 1845 a Cambridge mathematician, John Couch Adams, predicted the existence of another new planet, his theory was, for obscure reasons, ignored by the scientific establishment.

Observing the fact that Uranus was being pulled slightly out of its orbit, Adams worked out that there was another, as yet unknown, body in proximity - and correctly calculated its position.

His theory was presented to the Royal Observatory in Greenwich. But, occupied as it was with vital work on navigation and time-keeping (the search for longitude), the Observatory paid little notice.

The Astronomer Royal, Sir George Airey, took an interest only when a French mathematician, Urbain Leverrier, produced the same calculations. A Cambridge astronomer was commissioned to find Neptune in July 1846, but by September of the same year, Leverrier had beaten Britain to it, with the help of astronomers at Berlin Obervatory. A national scandal ensued.

The Royal Astronomical Society is running a competition for schools, asking primary and secondary pupils to produce a newspaper telling the story of the discovery. It will be judged in three age categories. Further details from Dr Margaret Penston on 01223 374000

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Nicholas Pyke

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