The Dome

There are few images more iconic in astronomy than that of the telescope dome. Sometimes seen with the telescope itself projecting from the viewing slit, these weather beaters are often a sure sign that astronomical observations are made here.

A stylised astronomical observing dome

A stylised astronomical observing dome

Why domes?

Well actually, they aren’t all domes. It is just the most well-liked of the various types of telescope covers out there. There are also sheds that open up or roll away from the telescopes, or huge blocks that split apart and reveal the instruments inside. Either way, the overall effect is to produce a self contained unit where a telescope can sit that won’t let the rain in, won’t block out part of the sky and won’t hold in heat or do anything that causes thermal turbulence of the atmosphere the telescope has to look through. In many cases the modern observatory is composed of the telescope dome and the control room set away from the dome. The dome itself usually has a slit for the telescope to view through and is capable of rotation to face whatever the telescope is out to see.

Observatory House, Durham University

The Observatory, Durham University

Of course domes have a long and fruitful history. The dome of my own dear UCL is based on the National Gallery, which is based on that of St Paul’s cathedral, which was designed by the astronomer and occasional architect Sir Christopher Wren to be an active observatory.

St Pauls cathedral

St Paul's cathedral

Where can domes be found?

Astronomical observatories can be found all over the place. In the grounds of UCL, where astronomy was first taught to UK undergraduates, two observing domes flank the portico. Although these aren’t used for actual astronomy anymore, they are kept up to date and see great use by the art department… Operations at UCL have since shifted to the dedicated University of London observatory at Mill Hill.

Fake dome, observing dome and architectural dome at UCL

Fake dome, observing dome and architectural dome at UCL

Earlier, I also showed a picture from Durham University’s observatory, below I will show one from Queen Mary College – in fact many universities with an astronomical department will either have an observatory of their own or some affiliation to one (such as Jodrell Bank’s affiliation to Manchester University). So for those dome hunters out for a bit of astro tourism, universities are usually a good place to start planning a tour. Many of them will have public open days, so check websites for those.

Queen Mary Colleges dome on a flat roof

Queen Mary College's dome on a flat roof

There are a number of institutions outside of universities that have observatories attached – planetaria, museums and science centres. These include such luminaries as the Royal Greenwich Observatory, Edinburgh Royal Observatory, Armagh Planetarium, Mills Observatory (retaining a papier mache dome), The Observatory (built from leftover pieces of the Greenwich Royal Observatory) and the new Kielder Observatory. There are also a number of places where you can stay overnight and make use of telescopes such as the Galloway Astronomy Centre, which has its own well equipped observatory and also Loch’s House and the Table’s Hotel, both of which offer the use of a telescope under dark skies.

ULO, Mill Hill, London

ULO, Mill Hill, London

But where to professional astronomers go to get their photons? Well, when not doing simple observations on telescopes like the ones above, professionals can book time on one of a series of large telescopes out there. These telescopes have been placed in positions where they’re relatively free of light and other forms of pollution, have clear skies and on occasion are pretty high up to allow some infra red through. These places include Mauna Kea in Hawaii – including the United Kingdom Infrared Telescope (under threat due to recent funding cuts), the Keck Telescopes, which are two of the most sought after instruments on the planet, the Infra Red Telescope Facility, Gemini North and Subaru as well as a number of radio and other telescopes – Roque de los Muchachos Observatory in La Palma – including the William Herschel Telescope (the largest presently there), Isaac Newton Telescope (the first on the site, moved from The Observatory in ’75 when it was the RGO), Swedish Solar Telescope (the largest refracting telescope in operation), SuperWASP (which looks for extrasolar planets) and the Liverpool Telescope amongst several others – the Paranal Observatory in Chile – presently the site of the Very Large Telescope array, with several others under construction – the Palomar Observatory, known for its survey of the night sky and the Anglo-Australian Observatory. Naturally, there are hundreds of others.

A telescope control room

A telescope control room

Many professional telescopes are funded through legacies, or privately owned, which secures both their future and direct a set amount of time to observing particular targets (like planetary astronomy, which benefits a lot from this, and survey astronomy), whilst others suffer from the fluctuations of government spending. As well as ground based observatories, there are space based ones like Hubble, the IUE, Chandra, XMM Newton and others, but as these are rather difficult to visit, they’ll wait for another time.

Telescope in a dome

Telescope in a dome

What about observatories in gardens?

There are a number of models of observatories for people to own for themselves. These can range from tent like things just to cut out excess light pollution, to adaptions to sheds that produce roll off roofs, or even roll off everythings and then up to the level of say Terry Pratchett’s customised observatory, which resembles an artistically tiled version of one of the domes in the UCL front quad, such as below (but without the umbrella).

Innovation at UCL

Innovation at UCL


4 responses to “The Dome

  1. Andrew Bowden

    Found this page whilst trying to find out some information about my old university accommodation in Durham. I lived in Observatory House which is actually the building near to the Observatory (the Observatory was just called The Observatory I think.)

    I spent my first year living on Obs House (as we tended to call it.) My room had a view looking out on the garden. Nice place.

  2. Thanks for that. The error came from the driveway, which lists The Observatory, Observatory House and Observatory Cottage on one plaque. Confused tourists like me, having just trudged halfway through Durham in the snow, get even more confused very easily…

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