Britain’s newest planetarium reached a milestone this weekend when the final piece of its brass cladding was lowered into place by crane.
The “full metal jacket” gives the new structure at Greenwich, south east London, a dazzling new shine as work goes ahead.
The planetarium is part of a £15 million redevelopment of the historic Royal Observatory.
As the last of 18 giant brass plates were being fitted to the building’s dramatic conical shell, it took on the look of a giant Dalek.
The project is the largest single use of the metal in the world. Each bronze sheet is 8mm thick (just under a third of an inch) and the total used weighs 32 tonnes.
The brass, produced in East Germany, took 12 weeks to assemble on site after the sheets were fabricated by the company Responsive Engineering of Gateshead, Tyne and Wear.
On warm summer days the cone will stand an inch (25mm) taller than on cold winter nights because of the way the brass expands.
Over the next 21 weeks, the plates will be welded together and treated with a secret-recipe acid solution to give it an aged patina finish.
Then another striking addition will be made to the shell – a flat glass mirror across the sloping top of the sliced-through cone.
It will be a stunning site as it reflects the blue sky or clouds during the day and the Moon and stars by night.
The Peter Harrison Planetarium, named after one of Britain’s richest men who donated £3 million to the project, is on target to open next spring.
It will be London’s only star theatre, following the decision by Madame Tussauds to close the London Planetarium in Baker Street in July, and will seat 120 in comfort.
A state of the art projector will send the audience on spectacular journeys into space with some dazzling effects.
The cone is a modern design but with a very traditional astronomical form. It is tilted at 51.5 degrees, the latitude of London, to point towards the Pole Star and the slice is made at right angles to align with the celestial equator.
Greenwich astronomer Dr Robert Massey said: “We’re well ahead with a facility that will benefit everyone in London and set the standard for planetariums across Europe.
“Greenwich has always been a centre of pilgrimage for astronomers. Some of the earliest measurements of the stars were made here.
“This is a brave design but we’re connecting the illustrious past with the present. We want to bring the excitement of astronomy to everyone.”