Star Globes

Star Globes

Some historians regard early star globes or celestial spheres as forerunners of the modern planetarium. This is reasonable enough, since the motion of the seven wanderers (the Greek name for the Sun, the Moon and the five planets we can see naked-eye from the ground) can best be studied in relation to the background of “fixed” stars. The earliest extant star globe is that of the Atlante Farnesiano, a marble statue in the National Museum, Naples, Italy. The statue shows a kneeling figure of Atlas, some six feet high, whose broad shoulders support a celestial globe 26 inches in diameter.

Instead of showing stars, the globe has 42 constellation figures carved on its surface and raised lines for the celestial equator and the ecliptic, or apparent path of the sun. The arrangement of the figures relative to the lines suggests that the globe was made about 300 B.C.

A similar emphasis on constellation figures is found on later star globes, and also on star charts. To most early astronomers, constellation figures were an essential part of cosmography, or the charting of the heavens. The great Danish astronomer Tycho Brahe spared no expense to have them drawn on his large star globe, completed about 1595. They decorated the famous star atlas which John Flamsteed prepared in the following century, and almost overwhelm the stars in Bode’s large atlas of 1801. Indeed, they appeared on most popular star globes and charts right up to modern times.

Gottorp Globe. Gottorp Celestial and Terrestrial Globe, reconstructed. The Atwood Star Globe in the Museum of the Chicago Academy of Sciences

The Gottorp Globe

A bid disadvantage of a celestial globe is that any stars marked on it are seen from the outside and therefore in mirror-reverse to those seen in the real sky. Adam Oeschlager, court mathematician and librarian to Duke Frederick of Holstein-Gottorp, designed a hollow globe large enough for several people to sit inside and see objects painted on the inner surface. The globe made of copper and eleven feet in diameter, was prepared between 1654 and 1664 by Andreas Busch of Limberg, and assembled in the Duke’s castle of Gottorp.

The outer surface of this globe showed a map of the then-known world, and a wide horizontal circle enabled visitors to walk around the globe and examine the map in detail. The inner surface, lit by two oil lamps, showed gilded stars and constellation figures. Inside, a circular platform suspended from the axis of rotation held as many as ten people, and as the globe rotated, many stars and constellations drifted across the artificial sky in a way similar to that of the real sky.

In 1715 the globe was sent as a present to Czar Peter the Great, who in turn presented it to the Academy of Sciences of St. Petersburg. In 1747 it was so badly damaged by fire that only the axis and a few bars of a framework remained. It was rebuilt in 1778, given more up-to-grade features on both surfaces, and is now on display at the Lomonosov Museum, St. Petersburg.

The globes of Weigel, Long and Atwood

The next globes of this type were made by Erhard Weigel who, from 1653 until his death in 1699, was professor of mathematics in the University of Jena. One of them is said to have had a diameter of about eleven feet and to have been made of iron sheets. Weigel was proud of the fact that his artificial sky could be seen at all hours of the day and night, in sunshine and in rain. In the middle of the globe, above the observing platform, a small model earth added a nice touch of realism. The model earth contained working models of Aetna and Vesuvius which gave out steam, flames and “pleasant odours”. Meteors, rain, hail wind, thunder, and lighting could also be reproduced. If spectators experienced all these in succession they must have emerged with a greater sense of appreciation of the world outside.

One of Weigel’s smaller globes is now in the Franklin Institute, Philadelphia. It is about 18 inches in diameter and its stars are formed by little holes pierced in the globe. To see them the observer looks into the dark interior through one of several larger holes cut in comparatively starless areas.

Another similar globe was designed by Roger Long, Lowndes’ professor of astronomy at Cambridge, and erected in 1758 at Pembroke College, Cambridge, England. It had a diameter of 18 feet, could carry about thirty people on its platform, and had star represented by holes of various appropriate sizes. The whole device could be rotated by which and rackwork.

Long hoped that his “Uranium”, as he called it, would encourage popular interest in astronomy but attendances were poor and although a keeper was paid six pounds a year to keep the apparatus in good running order, it gradually fell into a state of disrepair. In 1874, no longer in use, it was broken up and sold as scrap metal.

A far more successful project was the globe constructed in 1911 for the Chicago Academy of Sciences after a design by W. W. Atwood, president of Clark University. This has a diameter of 15 feet and is still in a good state of preservation in the Academy building in Lincoln Park. Made of thin galvanized sheet-iron, it weighs only 500 pounds and rests at its equator on electrically driven rollers. The stars are formed by numerous holes, all carefully graded in size and properly positioned, and the sun is represented by a small electric light, movable along the ecliptic.

Orreries in the Ceiling

Orreries in the Ceiling

One of the most unusual orreries was that built by Eise Eisinga, a woolcomber of Franeker, near Leeuwarde, in West Friesland. Its construction, begun about 1774, took seven years. The mechanism, weight-driven and regulated by a pendulum, consists largely of cog-wheels in the form of oak disks and hoops fitted with iron pegs. It is all concealed. The pendulum moves inside a cupboard-bed, the weight hangs in an adjoining wardrobe, the main cog-wheel assembly is built into an attic, and the working parts of the model solar system are mounted in the double ceiling of a living room. Visitors in the living room therefore see the face of the orrery, about 12 feet in diameter, above their heads. The model planets move in eccentric slots in periods equal to those of their natural counter-parts. Each slot or orbit carries the symbols of the zodiacal signs, and each sign is subdivided, thus enabling the zodiacal positions of the earth and any naked-eye planet to be read off quite easily. Outside the orbit of Saturn a pointer, moving in another slot, indicates the date and the sun`s position in the zodiac.

On the south side of the ceiling Eisinga arranged dials for showing the day, the months, and year, the moon`s phase and position, and the times of its rising and setting. In a panel over the cupboard-bed is the face of an ingenious moving sky-chart from which one can see at a glance what stars are above the horizon at Franeker at the time of observation.

Ceiling Orrery. Source: object.com

In 1787, only six years after completing the planetarium, Eisinga had to leave his home and family and seek safety abroad. Against his will he had become involved in political differences and civil strife. His exile lasted eight years, during which time his wife died, his house was rented to strangers, and the planetarium became neglected. In 1796, however, he had it going again and was able to remain with it until his death in 1828. After his death the house was presented to the community of Franeker by King William III and the planetarium has been kept in working order ever since.

Another large ceiling orrery was constructed in the early 1920`s for the Deutsches Museum, Munich. Designed by Franz Meyer, chief engineer of the firm of Carl Zeiss, it occupied a circular room 37 feet in diameter. In the centre a sun globe, nine inches in diameter and suspended from the ceiling, contained a 300-watt light-bulb which provided illumination for the entire room. Smaller globes for the planets, suspended from electrically driven carriages, moved on elliptical rails with speed proportional to their natural velocities. The spectator went round the model sun on a moving platform located directly beneath the earth globe, and by using a periscope could watch the planets as they moved against a background of constellations painted on the walls of the room. Unfortunately, the orrery was destroyed during World War II, but modern versions of the ceiling orrery can be seen at the American Museum-Hayden Planetarium, New York, and the Morehead Planetarium, Chapel Hill.

Orreries

Orreries

The next major development came from England where Thomas Tompion, the famous London clockmaker, and his colleague, George Graham, made a working model of the earth-moon-sun-system. It is now in view in the Museum of the History of Science, Oxford. Between 1704 and 1709 Graham made a similar machine for Prince Eugene of Savoy, and of this John Rowley, another instrument-maker, made several copies. One of them later went to Charles Boyle, fourth Earl of Orrery, an association which inspired Sir Richard Steel, editor and essayist to christen the machine an “orrery”.

The Rowley-made orrery sent to Boyle is owned by the present Earl of Cork and Orrery, and now is on loan to the Royal United Service Institution, London. The mechanism drives a model moon around an earth which in turn revolves about a model sun and is enclosed in a twelve-sided ebony and gilt case 30 inches in diameter and about nine inches deep.

Orrery made by John Rowley for Charles Boyle, fourth Earl of Orrery. Source of the photo : ScienceMuseum.org

The fame of the orrery soon spread far and wide and encouraged several London instrument makers to construct similar machines. Many were large, complicated and expensive. For example, the “Grand Orrery” made by Thomas Wright in 1733 showed the motions of the moon, earth, and five then-known planets about the sun, and is said to have cost 1,500 pounds. It was housed in the Royal Observatory, Richmond, and is now on loan to the Science Museum. London.

The first American-made orrery appears to have been a simple wooden model built in 1745 by Thomas Clap, president of Yale College. This was followed by a much more elaborate machine, constructed in 1770 by David Rittenhouse, astronomer and horologist. His aim was not to amuse or amaze the layman who, as he bluntly put it, was “ignorant of astronomy,” but to use the machine as a teaching aid for those who wished know more about the structure of the solar system. The model planets, unlike those of most earlier orreries, moved in elliptical orbits, and the entire mechanism and face plate were mounted vertically in a handsome cabinet. The orrery is now in the Library of the University of Pennsylvania while another, similar in design and construction, is in the Library of Princetown.

Early Models of the Solar System

Early Models of the Solar System

In the 17th century, with the rapid development of the mechanical sciences, the first attempts were made to demonstrate by models the relative motions of the moon and planets on a sun-centered or heliocentric basis. In Paris, the Danish astronomer Ole Römer, famous for his discovery of the finity velocity of light, devised machines which showed the relative motions of four of Jupiter`s satellites, and the satellites and ring of Saturn. Another of his machines, completed in 1680, showed the motions of the planets about the sun, and of the moon about the earth. The gearing, hand operated, lay behind a vertical plate in which elliptical slots represented the orbits of the planets, while in each slot moved a spindle surmounted by a small model planet. This planetarium made a great impression in Paris and copies were sent to Persia and China.

Solar System

In 1682, Johannes van Ceulen of The Hague made a small planetarium to a design provided by the Dutch scientist Christian Huygens. In his design Huygens solved the problem of using only a small number of simple gear-wheels to drive model planets at approximately the correct proportionate speeds. The machine, now in the National Museum of the History of Science, Leyden, takes the form of an octagonal box about 26 inches across and seven inches deep. Under the action of a clockwork mechanism, the model planets move with uniform motions in circular slots cut in the copper faceplate.

The actual planets, however, move with non-uniform motions in elliptical orbits. As a first approximation to this requirement, Huygens arranged the circular slots with their centres displaced from the central sun globe.

When will we announce that other worlds really exist? Image: Close Up © Megan Jorgensen (Elena)

McLaughlin Planetarium Building

The Planetarium Building

(The McLaughlin Planetarium was closed in 1995)

For some years there had been discussion in Toronto about the need for a major planetarium. One proposal, made in July, 1962, took the form of a bequest of $10,000 made by a former member of the Royal Astronomical Society of Canada. His intention was that the Society, either alone or in collaboration with the Royal Ontario Museum, should consider establishing a major planetarium in Toronto within ten years. In May, 1964, the President of the University of Toronto and the Chairman of its Board informed the National Council of the Royal Astronomical Society of Canada that it was enthusiastic about the idea of having a good planetarium connected with the Royal Ontario Museum. They added, however, that the necessary financial support would have to come from quarters other than those required to maintain the university’s large and urgent academic expansion program.

The project is launched

The necessary financial support came unexpectedly in November, 1964, when Colonel R. S. McLaughlin, in a telephone call to the Director of the Royal Ontario Museum, offered to donate approximately $1,000,000, a figure which he later increased to $2,000,000. Asked about his reason for the donation, Colonel McLaughlin answered: “Charlie Hayden was a great friend of mine. He was Chairman of the Board of Directors of International Nickel; I worked with him for several years and liked him very much. When he decided to have the Planetarium in New York built, I was very interested. My wife and I drove there when it was completed and I came back full of enthusiasm. At the time I had a few architects come along (this was more than 20 years ago) to find out what the chances were of erecting a Planetarium here.

“To our great disappointment, we could not get equipment here as it was not available anywhere in the world, and I, therefore, gave up the idea for the time being. When a few weeks ago my secretary brought me a newspaper cutting from a Toronto newspaper, where it was again mentioned that there was interest in building a Planetarium, I sent out a man to make enquiries. On his return, he indicated the equipment was now available in three countries. I telephoned the Director of the Museum and told him that if they would allow me to, I would like to have a Planetarium built for them. It would give me great pleasure to see it completed.

A month later a “users’ committee” under the chairmanship of the associate head of the Department of Astronomy, began to draw up detailed requirements for the project. One important result of its deliberations, combined with visits to other planetariums, was an outline proposal for the building. Stone and Webster Canada Limited, project managers and engineering consultants, in association with Allward and Gouinlock, consulting architects, then prepared the necessary detailed drawings and specifications. In December, 1966, the contract for the construction of the building was awarded to Milne and Nicolls Limited of Toronto, and work began on the site.

The Outer Dome

The MacLaughlin Planetarium stands on the site of an old house, at one time the residence of the President of the University of Toronto, at 86 Queen’s Park, directly south of the Royal Ontario Museum. Its most striking feature is the dome, which rises some 83 feet above the roadway, has an outer diameter of nearly 91 feet, and is built in layers like a sandwich. The inner or main shell is of reinforced concrete four to eight inches thick. This is overlain by a layer of foamed urethane and an outer shell of reinforced concrete 1 ½ inches thick. The outer shell is waterproofed with synthetic rubber material.

The building has two entrances for visitors – the main or street entrance, set back about 80 feet from the roadway, and a secondary, approached through the mineralogy gallery of the Royal Ontario Museum. Visitors who use the street entrance enter a main lobby or assembly area with its sales desk, coat room, and washrooms. Then they proceed by easy flights of stairs to large display areas (designed by Opus International Limited), and in so doing become gradually reoriented from earthly surroundings to objects in the depths of space. This psychological transition, encouraged by subdued lighting and the nature of the displays, is maintained right up to the entrance of the star theatre on the third floor.

The Projection Dome

The projection dome, just under 75 ½ feet in diameter, is physically independent of the outer dome. The space between them contains movable ladders (for gaining access to loudspeakers mounted directly behind the projection dome), and a gantry for reaching projectors and lights contained in the cove at the dome’s base.

The Projection dome was made by Astro-Tec Manufactured Incorporated of Ohio. It consists of carefully-shaped sheets of aluminium held in place by a framework of slender ribs. The sheets are lap-jointed to form a continuous surface accurately spherical to within 1/5 of an inch. At the close range, however, the surface is seen to be perforated with tiny holes at ¼ inch intervals. The holes are just under 1/10th of an inch in diameter and therefore are too small to interfere with even the smallest star images. Their function is to allow parts of sound waves to pass through the inner dome and be absorbed by sound insulation boards. This reduces the reflection of the waves and the formation of disturbing echoes. Finally, coats of special white paint are applied to the surface to ensure that it is a good reflector of light.

The millions of tiny holes in the projection dome also play an important part in the ventilation of the star theatre. Cool filtered air enters the theatre through the space between the outer and inner domes, and leaves through ducts at the base of the Zeiss projector. The coolness encourages the illusion of being outdoors on a clear, starry night, while the absence of dust particles ensures that light beams from the projectors to the dome remain invisible. Actually, the entire planetarium building is air conditioned, thereby creating a free, open feeling on even a warmest of days.

Every major planetarium should have a mechanical workshop to adequately maintain the moving parts of exhibits in the display areas and the optical projection assemblies. A workshop also is necessary for the development and construction of new exhibits and projectors. The McLaughlin planetarium has a large and well-equipped workshop on the first floor, directly below the spiral staircase in the north wing. There the technical staff can build almost any type of supplementary projector to ensure that the shows and lectures have the greatest possible interest, scope and variety.

Everything possible has been done to ensure that the McLaughlin Planetarium is one of the best of its kind in the world. Although a major planetarium, it is not by any means the largest, nor does it have, by reason of its location, an associated public observatory or observation deck. On the other hand it is a model of compactness – not a single square foot has been wasted – and represents an outcome of an immense amount of thought and planning. Its success will be measured not by its size, nor necessarily by the number of visitors who enter its doors in a year, but by the integrity with which it presents astronomy and the quality of its service to the community.