MONTEVIDEO – An enormous metallic contraption dominates the auditorium of the Montevideo Planetarium.
The Spitz Model B projector is the oldest functioning device of its kind in the world, projecting a map of the night sky onto the dome of the hall that the public has come to see for more than 60 years.
The Spitz began operating in 1955 and it opened up the heavens to the Uruguayan public, the institution’s director, Oscar Mendez, told EFE.
By means of a delicate system of gears, the instrument – weighing more than 500 kg (1,100 lb.) – can be moved and shows the relative positions of the stars from any latitude on Earth thanks to dozens of tiny holes through which small beams of light project onto the dome’s ceiling.
“One half-sphere shows the sky in the northern hemisphere and the other shows the southern sky,” Mendez said.
During public demonstrations, the dome of the planetarium darkens and little by little first the planets appear, then the brightest stars and then the rest of the celestial bodies visible to the naked eye.
There is a separate projector for each of the five visible planets – Mercury, Venus, Mars, Jupiter and Saturn – along with one for the Sun and another for the Moon, and one more for the imaginary figures of the constellations, Mendez said.
The control mechanism is automatic and each week it is altered to correspond to the shifting cycles of the year’s seasons, thus keeping the planetarium’s current depiction of the sky in tune with the actual sky.
Each year, planetarium workers service the projector, taking the instrument down to make repairs and to work out solutions to various problems that crop up over time, although many of the device’s parts are no longer made.