Does Uranus Look Big In This? (The Neptune File - Tom Standage)

Member Name: pje

Product:	The Neptune File - Tom Standage
Date:	16/01/02 (57 review reads)
Rating:

Advantages: Fascinating history of discovery.

Disadvantages: Bumbling Brits.

I was on my way back from town last night, and up in the clear twilight sky there was one star shining brightly. Ahhh. Well, I say star, but presumably it was Venus, our nearest neighbour in the Solar System, after the moon.

Before March 13th, 1781, it was believed that there were just five other planets in the Solar System besides the Earth. (Namely:- Mercury, Venus, Mars, Jupiter and Saturn.) On that night a musician called William Herschel erected his seven foot telescopic instrument, looked up, and saw Uranus - unleashing an astronomical number of double entendres onto an unsuspecting universe.

What neither Herschel nor anyone else knew, was that his home-made telescope was the biggest in the world at that time. Even through this mighty instrument though, Uranus was merely a "fuzzy blob". Initially, Herchel presumed it was a comet, and informed the Astronomer Royal (Nevil Maskelyne) and it was he who was the first to suspect that it could be a 'new' planet.

When they were told about it, Royal Society members were, at first, rather sceptical about Herschel's discovery. They couldn't believe he was telling the truth about the size of his instrument, and, since none of them had such a whopper, they had trouble verifying it. In fact, it later transpired that Uranus had been spotted before by a number of astonomers, but, as it was merely a spot of light in their puny telescopes, they had mistaken it for a star. Y'see? Sometimes size does matter...

The kudos associated with his discovery led to some lucrative orders for him to make big telescopes for other astronomers across Europe and he also became the private astronomer to King George III. It's not quite true to say that Herschel wanted to call the new planet George after his royal master - he actually proposed the name Georgium Sidus (the Georgian Star). It was a German astronomer (Johann Bode) who thought of Uranus. (Who said Germans don't
have a sense of humour?)

However, star-gazers were soon perturbed - or rather Uranus was. Nobody's calculations for the orbit of Uranus seemed to fit, there were mysterious perturbations, leading to speculation that there was something else out there...

Enter our hero, John Couch Adams (born in Lipcot, Cornwall, in 1819).
A maths prodigy, Adams comes across as being too good to be true.
For example, when his brother was stuck on an algebra problem,
John advised him to persevere, remarking that: "the harvest does not immediately follow the sowing." (His brother's response is not recorded.)

He thoroughly thought through every problem in his head before putting pen to paper, and this is why his cleaning lady would often find him lying on his sofa (not a couch, disappointingly) without a book in sight.
[Insert your own favourite joke about lazy, onanistic students here.]

Adams was determined to predict mathematically, the position of whatever was responsible for the irregularities in the orbit of Uranus,
and eventually he succeeded. But when he gave his findings to the then Astronomer Royal, George Airy (also a Cambridge man), he was told to keep it under his hat until Cambridge astronomers could pinpoint it.

Unfortunately, over in France, Monsieur Urbain Jean-Joseph Le Verrier was hot on the trail too, and had soon calculated a position for the new planet very close to Adams's prediction, using a different mathematical method. But he didn't sit on it, no. He asked a colleague at an observatory in Berlin to have a look for it, and on September 25th, 1846, Johann Gottfried Galle wrote to Le Verrier, saying:

"Sir, the planet whose position you have pointed out actually exists."

Professor James Challis, the director of the Cambridge Observatory, who had been scouring that part of the heavens for months, later realized that he'd recorded observa
tions of the planet several times, but had been too busy to analyze those observations. Is it any wonder we lost our empire?

Of course when Adams' work was made public the French were outraged, believing that the British were trying to steal Le Verrier's glory, and British astronomers outside Cambridge were (I'm sorry, but I can't resist the pun here) galled. Airy was never really forgiven, but Adams did receive the credit he deserved (including a memorial plaque in Westminster Abbey) although being a modest farmer's boy, he turned down both a knighthood and the post of Astronomer Royal. Ohhh, and in 1884 he represented Britain at a conference in Washington D.C. which decreed that the global benchmark for zero degrees longitude would be the Greenwich meridian - a line first drawn up by George Airy! Final score: England 1 France 1.

But wait, wasn't there something else out there? Percival Lowell (the guy who thought he saw canals on Mars) was so convinced that a 'Planet X' existed beyond Neptune that he set up his own observatory in Arizona to look for it. But the American's efforts were much more hit and miss, and he died disappointed. However, his nephew took up the cause and a student he employed, by the name of Clyde Tombaugh, using the new technique of astrophotography, found another planet (I'd like to tell you that he said "hi there, P-luto" when he found it, but that would be silly). It was a fluke, though. Data from the Voyager 2 spacrecraft allowed the mass of Neptune to be calculated more exactly, and this correction ironed out the remaining discrepancies in the outer planets' orbits.

But there are still a lot more planets out there, waiting to be discovered, whizzing round other stars light years away. And in 1995, the first one was found by two Swiss astronomers using a method based on the effect that a large planet's gravity has on its star, which causes it to 'wo
bble'. Since then more than forty other planets have been 'found', sight unseen.
And new techniques, and new space-telescopes will find more and more...

Tom Standage writes about science in The Economist magazine, by the way, and his first book was called The Victorian Internet. The Neptune File is a compact, but detailed account of 'planet hunting' then and now, which anyone with any interest in astronomy will enjoy.


¶ Hardback: £12.99 ¶ pp 215 ¶ ISBN: 071399472X ¶
¶ Paperback: £6.99 ¶ pp 240 ¶ ISBN: 0140294643 ¶
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