Thom Dibdin clambers up Calton Hill to Edinburgh‘s City Observatory. where they‘re awaitingthe arrival ofa crusty old comet.
At the top of Edinburgh‘s Calton Hill. cloistered behind a wall which would make a Rottweiler baulk. squats the (‘in Observatory. Outwardly just another pseudo-Greek edifice. the facade provides a fitting temple for arcane astronomical delights.
The wall maybe tall and the delights mysterious but Jamie Shepherd. the ()bservatory‘s part-time director. is more than willing to open the gates for any neophyte who wants to explore the astronomer‘s craft. This is. after all. Edinburgh‘s own observatory. given to the city in 1896 when the Royal - Observatory moved out to Blackford Hill. where the city lights did not brighten the night sky.
"l‘he city fathers became very enthusiastic about the place.‘ says Jamie. "l‘hey put in a new dome and installed a 22in telescope. As an afterthought William McEwan. the brewer and MP for (‘entral
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Edinburgh at the time. bought a bin '(‘ook refractor as a gift to the people of Edinburgh so that they would no longer be without a means of examining the heavens.‘
The larger machine was old. It never performed well and was scrapped in the 1920s. But the (‘ook refractor. a brass monstrosity. more like a Vogon gun emplacement from a Dan Dare epic than a star-gazing device. still stands on a pillar of granite in the top of the observatory. ‘It is the finest piece of telescope craftsmanship in Scotland.‘ boasts Jamie. ‘Where it scores over other telescopes is that it has a triplet lens
with three slices of glass. compared to the normal two. which gives a very sharp image. Unfortunately. we are too close to the centre of Edinburgh to see much in the way of faint objects. but this is great for looking at the planets or the moon.‘
During the day the telescope can be pointed towards the sun and its image projected onto a piece of card. so visitors can examine sun spots. But. Jamie says. "l‘he most exciting time is when something is happening in the sky. eclipses of the moon or the sun or when a comet comes past.‘ Provided the ‘seeing is good‘. Jupiter
Contact Society treasurer John Rostron on ()31 669 5664 for further details of the Society. For group visits to the Observatory. phone Jamie Shepherd on ()31 5564365.
I The Astronomical Society of Edinburgh meet on the first Friday ofevery month at the City Observatory. Calton Hill. at 8pm. This Friday. 4 May. DrJohn Reid will be
showing his astro- I The Royal Observatory photographic calendar— a on Blackford Hill. collection of photographs Edinburgh. has the
of the heavens. taken over the past year. Providing the weather is fine. there will also be an opportunity to see Jupiter through the Cook 6in refractor. Admission is free.
exhibition ‘A Star and its Planets‘ in the Visitor Centre. This includes an excellent panel on comets and a leaﬂet about Comet Austin is available. Open 10am—4pm weekdays;
noon—5pm weekends and holidays. Entrance £1 (65p). Phone 031 668 8405 for details.
l The Astronomical Society of Glasgow holds its next meeting on 20 September when Scotland‘s Astonomer Royal. Malcolm Longhere. will be talking about the Hubble telescope. Contact Malcolm Kennedy. 32 (‘edar Road. Cumbcrnauld. G67 38”. ()236 725499.
with four of her moons will be visible close to our moon after the Edinburgh Astronomical Society‘s meeting this Friday (see listing). Sadly. the last lunar eclipse was in March. the next solar one will be in July. and then best visible from northern Finland. and the current comet simply is not performing as was hoped. ‘We do not expect comet Austin to be a blazing spectacle in the sky.‘ comments Jamie. adding rather ruefully. ‘comets are notoriously difficult for working out
A PUBLIC FESTIVAL
how bright they are going to be.‘ Under the headline. ‘C‘omet Austin Looks Set to be a Beauty‘. one popular astronomy magazine even reckoned it would be possibly ‘one of the brightest comets this century!‘
When the last bright comet came past. Halley‘s in 1986. the queues wound twice around the walls. But Austin will only be visible in the early morning. a wispy trail in the north-eastern sky. best seen by late revellers on their way home.
Over at the Royal Observatory on Blackford I lill. Press Officer Russell liberst. who has seen Austin himself. explains that the problem of prediction is due to the nature of a comet. As it nears the sun. the core of ice has to heat up sufficiently to boil and break through the comet‘s skin ofstellar dust.
Like Jamie. Russell is excited by the theory ofcomcts. although they espouse different ideas about their origin. "l‘he sun has a perpetual cloud ofcomcts.‘ he explains. ‘Most are at a great distance. but from time to time they drop in towards the sun. 'l‘hey travel along with the sun. but every million years the earth passes through a huge cloud of interstellar dust. The effect of this is that the cloud is stripped off. and a new set of comets is captured.‘
Back at (‘alton Hill. Jamie explains the contrasting theory. which he believes more elegant. ‘Somehow comets are focused by the process of the sun passing through clouds of interstellar dust. The dust congeals
along an axis behind the sun. and then that congealed stuff drops in towards the sun. from the leeward side. as it were.‘ This would explain why comets tend to come in families.
Despite such esoteric niceties. an evening‘s star-gazing with Jamie is a delight. During the last lunar eclipse in March. like a Latter-day Pied Piper in his multi-coloured jumper. he led the crowd already assembled on (‘alton Hill up the winding stairs to view the darkened moon glowing an alien orange in the evening sky through the vast brass monstrosity. Forget Hubble. Ignore Jodrcll Bank. This is hands-on astronomy at its best.
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The List 4— 17 May 199095