Out of this World

Europe’s early maps of the universe brought the stars down to earth and into people’s homes By Jeffrey S. Murray

Not everyone in Europe was comfortable with using constellations based on pagan mythology. Published in the early 1600s, the Augsburg lawyer Julius Schiller attempted to popularize the night sky by filling it with Christian images. He used the New Testament for the northern hemisphere, the Old Testament for the southern hemisphere, and the twelve apostles for the zodiac. Photo courtesy: Library of Congress

As was the custom of the day, this 1729 chart of the moon’s surface shows the two competing systems of nomenclature devised for the moon. The one on the left was put forward by the famous Danzig (now Gdansk) astronomer Johannes Hevelius. The one on the right was devised by the Jesuit astronomer Giovanni Battista Riccioli and is still used today. Photo courtesy: Library and Archives Canada, e010771312

Published in the early eighteenth century, this chart of the northern sky is surrounded by four famous European observatories: Tycho Brahe’s on the island of Hven, Denmark (top left); the Paris observatory (top right); Johannes Hevelius’ private observatory at Danzig, now Gdansk, Poland (bottom left); and the Nuremburg observatory. Photo courtesy: Library and Archives Canada, e010771310

Ptolemy’s understanding of the universe, first published in the second century BC, satisfied European astronomers for more than 1,400 years. As illustrated in this 1661 celestial chart by Andreas Cellarius, the Ptolemaic universe had the known planets, the sun, and the moon orbiting the earth. The stars, as represented by the symbols of the zodiac, were thought to exist as a shell around the outer edge. Photo courtesy: Library and Archives Canada, e010771314

Andreas Cellarius’ novel chart of the night’s sky, published in 1660, has the constellations superimposed on an outline map of the earth. This view of the “back” of the celestial shell leaves the viewer with the impression of star gazing from heaven. The chart’s practical use was limited since the stars were a mirror image to what is seen from Earth. Photo courtesy: Library and Archives Canada, e010771319

Although Copernicus presented his theory on a sun-centered universe almost a century and a half earlier, Ptolemy’s earth-bounded view still had its supporters throughout Europe, as evidenced by this chart by Andreas Cellarius, published in Amsterdam in 1661. The earth surrounded by the water, air, and fire are at the center of the universe. Photo courtesy: Stewart Museum, Montreal, 979-527-1

Since earliest times, astronomers have relied on an imaginary framework of lines and circles for measuring the positions of the stars. This chart from the mid-seventeenth century features some of the more common ones, many of which are the same great circles that are used to divide the earth—the equator and the tropics of Cancer and Capricorn, for example. The constellation of the zodiac girdles the sky at 23 1/2 degrees to the equator. Photo courtesy: Library and Archives Canada, e010771316

An early engraving of the three major aids used by teachers and scholars of the 1700s (l-r): a celestial globe, an armillary sphere, and a terrestrial globe. Such tools helped to popularize astronomy by moving it beyond the realm of philosophers and into the home. Photo courtesy: Library and Archives Canada, e010771320

Armillary spheres, similar to the one in this 1715 engraving by Nicolas de Fer, were widely used throughout Europe for demonstrating movements of the planets. In this model, the earth is tilted on its axis and is at the centre of the universe. Such devices helped to reinforce the notion that the heavens were a great celestial machine, like a timepiece, which once set in motion would go on forever. Photo courtesy: National Archives of Canada, e010771321

It is the middle of the night when I lie down on the recently mowed hayfield beside our house at Burritt's Rapids in the Ottawa Valley to study the stars with my 7-year-old nephew. Even though I put a wool blanket on the ground, I can still feel the grass stubble poking into the back of my neck. It is a clear summer's night, and we are far enough from the city that there are no extraneous bright lights obscuring our view. We brought along our flashlights and a star chart of the northern hemisphere. With one light trained on the chart, we point the other into the sky and use its beam to trace the outlines of the constellations.

Our map is austere. It consists simply of white star symbols on a plain dark blue background, and although dotted lines group the stars belonging to individual constellations, the chart provides no clues as to how the stars fit in to their arrangement. Just where does Polaris sit within the constellation Ursa Minor—at the top or bottom? Just what or who was Ursa Minor, and what is he, she, or it doing in our sky? With this useful but aesthetically unappealing chart in hand, I cannot help lamenting how much celestial mapping has changed in the four hundred years since Galileo first turned his telescope skyward. His simple act might have forever changed humankind’s understanding of the universe, but it was Europe’s mapmakers who first brought the stars into people’s homes.

Modern-day historians say star mapping is at least as old as its terrestrial counterpart and might, indeed, predate it. Even at their best, though, European star maps of two millennia ago were little more than pictures of small pieces of the night sky, showing the approximate relationship between the stars and their alignment within a constellation. It was in 1515, just two decades after Columbus sailed to the New World, that German engraver Albrecht Dürer thought to put all the pieces together on one chart to give a complete representation of the heavens. Dürer not only charted all the northern-sky constellations together, he also printed coordinates from which star positions could be read with a reasonable degree of precision. In the process, he ushered in an entirely new form of art.

It is hardly coincidental that Dürer’s first star map appeared about a decade after the printing of the first terrestrial maps of the world and about half a century after the invention of a movable-type printing press by one of his fellow countrymen, Johannes Gutenberg. The two developments gave Dürer the theory and technology he required: The production of world maps provided the mathematical formulae by which a spherical shape could be projected accurately onto a flat surface; the printing press gave him the means by which to implement and disseminate his chart. More important, the introduction of the printing press ushered in the Renaissance, the rebirth of culture and society across Europe.

Celestial charts fit nicely into this new intellectual environment. Grouping the stars into constellations gave astronomers and navigators a useful frame of reference—a topography, if you like—to the night’s sky. With the wider distribution of star charts made possible by the printing press, knowledge of the stars could also be brought into the home and made a part of a child's education. As a mark of status, the more affluent not only wanted star charts hanging on the walls in their homes and bound into atlases in their libraries, but they also wanted them included in their paintings. Some families even had their portrait painted with everyone gathered around one of the many new devices that were capable of demonstrating the movement of the planets.

The amount of astronomical information included on the star maps varied: Some charts included the proper names of the important stars; others tried to distinguish between bright and faint stars by using symbols of different sizes or various types of tables that classified each star’s light intensity. They were mostly drawn as planispheres, just like the one my nephew and I had. That is, they were circular maps centered on one of the earth's poles and covering just one hemisphere. The stars of the zodiac—which can be seen by stargazers in either hemisphere—were arranged around the outer edge of the chart. Together, two planispheres showed the complete topography of the heavens. Initially the constellations were drawn as they would be seen on the surface of a celestial globe: with the viewer standing on the outside and looking from heaven through the stars to earth. This was the result of the mapmaker simply transferring to paper the star arrangement seen on a globe. It was not a very useful perspective by which to identify the constellations because everything on the chart was a mirror image of what could be seen from earth. Only later were star charts drawn as humans would see the stars when looking up into the night sky