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Uranometria
Taurus in Uranometria, Johannes Bayer, 1603, printed book. The Huntington Library, Art Museum, and Botanical Gardens. 482143.
Mapping the Night Sky
Title page in Uranometria, Johannes Bayer, 1603, printed book. The Huntington Library, Art Museum, and Botanical Gardens. 482143.
Johann Bayer (1572-1625) was not a trained scientist. He worked as a lawyer in Augsburg, Germany. He had an interest in astronomy and taught himself how to observe, research, and document the night sky. In 1603, he published his star atlas titled Uranometria. Uranometria is book containing 51 constellation maps of the night sky. The maps in Bayer’s star atlas were the most accurate and artistic ever produced at that time.
Because of its accuracy and artistry, Uranometria was very popular. For 200 years after its publication, the atlas was reprinted almost a dozen times. It inspired several other astronomers to create similar works. Bayer’s work continues to influence the way we understand and discuss the night sky. Bayer’s star atlas started the “golden age” of constellation maps.
Features of a Constellation Map
Star atlases, maps of the night sky, have been around for thousands of years. Between 1600-1800, it was very popular to create star atlases, and many astronomers, both professional and amateur, created their own maps of the night sky. These atlases depicted constellations and provided readers with information about celestial bodies, including their location and brightness. It is easier for people to identify groups of stars in the night sky than a single star, so constellations can be a helpful organizational tool for astronomers and navigators.
Almost every detail in Bayer’s constellation maps conveys information about Bayer’s thinking. In Uranometria, Bayer adopted, adapted, and developed several features of constellation maps. Use the interactive image below to explore these features.
Star Atlas Hercules
Star Atlas Hercules
Hercules (flipped 180°) in Uranometria, Johannes Bayer, 1603, printed book. The Huntington Library, Art Museum, and Botanical Gardens. 482143.
Classical Greek Traditions In the first century CE, the Greek astronomer Ptolemy identified 48 constellations in the night sky. Almost 2000 years later, astronomers like Bayer organized their atlases using the constellations provided by Ptolemy. Which of Ptolemy’s constellations have you heard of? What do you know about them?
- Ursa Minor
- Ursa Major
- Draco
- Cepheus
- Boötes
- Corona Borealis
- Hercules
- Lyra
- Cygnus
- Cassiopeia
- Perseus
- Auriga
- Ophiuchus
- Serpens
- Sagitta
- Aquila
- Delphinus
- Equuleus
- Pegasus
- Andromeda
- Triangulum
- Aries
- Taurus
- Gemini
- Cancer
- Leo
- Virgo
- Libra
- Scorpius
- Sagittarius
- Capricornus
- Aquarius
- Pisces
- Cetus
- Orion
- Eridanus
- Lepus
- Canis Major
- Canis Minor
- Argo
- Hydra
- Crater
- Corvus
- Centaurus
- Lupus
- Ara
- Corona Australis
- Piscis Austrinus
Myths and Stories Each constellation is a group of stars. These stars can be millions of light years away from each other, but from Earth they appear close together. Early astronomers looked at the sky and used their imaginations to assign myths, stories, and objects to different groups of stars. These familiar myths, stories, and objects helped people remember and locate the constellations. The stars in the constellation only provide a few points on the figure, so each astronomer artist had a lot of creative freedom in how they depicted the figures. Bayer’s artistic constellation maps give additional visual representation to the constellations. The constellation on this map is Hercules, a Greek demigod known for his superhuman strength and epic adventures that have inspired artworks, books, and theater for thousands of years.
Coordinate System the purpose of a map is to help people identify the locations and relationships between different objects in space. Constellation maps include a coordinate system that readers can use to understand the positions of different stars. Bayer included a grid on the edges of each constellation map. Readers can use a straightedge (like a ruler) to identify each star’s position to a fraction of a degree. Bayer was the first person to create such a precise grid, and his constellation maps were much more accurate than previous works.
Classifying the Stars Bayer developed a method of classifying and naming stars that is still used today. In each constellation, he assigned every star a Greek letter. He started with the brightest star, assigning it “alpha” (the first letter of the Greek alphabet). The second brightest star was assigned “beta” (the second letter of the Greek alphabet) and so on. If a constellation had more stars than the Greek alphabet had letters (24), Bayer continued his list with the Latin alphabet.
Star Catalog This interactive image only shows one side of the constellation map. On the back of each map, Bayer includes the Ptolemaic name for each constellation and a discussion of the different names of the constellation. He also includes a list of all the stars with information about their position within the constellation, their magnitude (brightness) and their astrological association. In his star catalog on the back of each map, Bayer provided two identifications for each star: his Greek (or Latin) letter identifier and Ptolemy’s number identifier. His new identification system provided more information to the reader, but readers were more familiar with Ptolemy’s system. Bayer helped his readers by including both.
Bayer’s Influences
Bayer’s star atlas started the “golden age” of constellation maps, but printed star maps existed prior to this period. Two likely influences for Bayer’s work are the illustrations of Jacques de Gheyn II, and On Fixed Stars by Alessandro Piccolomini.
The illustrations created by de Gheyn II in 1600 are artistic but not accurate. His work includes highly artistic representations of the constellations. The stars are inaccurately placed, and there is no coordinate system showing the stars’ positions in the sky.
Piccolomini’s On the Fixed Stars (published 1540) is accurate but not artistic. It includes a star catalog with mythological descriptions of 47 of Ptolemy’s 48 constellations. Piccolomini was the first astronomer to show the relative brightness of stars in his atlas; he lists the brightest stars with Latin letters. Piccolomini included a scale of degrees to help readers determine the size of the constellation, but he did not include a coordinate system. This meant readers could not locate individual stars. Each map included an accurate representation of the constellation’s star pattern as seen from Earth. None of these maps included artwork for the constellations.
Use the image slider below to compare and contrast de Gheyn’s II, Piccolomini’s, and Bayer’s versions of the constellation Orion.
Northern Hemisphere
In the first century CE, the Greek astronomer Ptolemy identified 48 constellations in the night sky. Bayer created 49 constellation maps, 48 of which are of Ptolemy’s constellations. Use the questions and prompts below to analyze one (or more) of Bayer’s northern hemisphere constellation maps.
Choose one of the above constellation maps. Allow the prompts and questions below to guide your observation. Once you’re done, you can choose a second constellation map and repeat the process. Compare your responses for the two constellation maps. You can also compare your responses to those of a peer.
Questions & Prompts
Look closely at this constellation map. What do you notice first? What do you notice after looking for a full minute?
How did Bayer use observations of the natural world when creating this work?
How did Bayer use his imagination and creativity when creating this work?
Does this work remind you of anything? What? Why?
What do you think Bayer was trying to communicate? What do you see in the object that makes you think that?
How does Bayer’s culture affect his understanding of the stars?
What do you know about the myth, story, animal, or object in your chosen constellation? Does this work tell a story? If so, what story?
Many of the constellations feature popular stories, people, and animals from Ancient Greece. If you were naming constellations today, what stories, people, and animals would you choose for the names? Why?
Southern Hemisphere
Bayer’s atlas includes 49 constellation maps, and 48 of these maps depict constellations in the northern hemisphere. The 49th map is special; it is the first European star atlas depicting the constellations of the southern hemisphere.
In addition to being the “golden age” of star atlases, the 1600s-1800s was a period of European colonialism and imperialism. Europeans referred to this period as the Age of Exploration. At a time when they were traveling the world by ship, it was essential that they knew how to navigate the open ocean. One of the few reliable methods for figuring out their exact location depended on having accurate star maps of these unfamiliar skies.
Bayer was the first to try to create an accurate star map of the southern hemisphere. He based his 49th map on observations made by three European explorers. He used their descriptions of 12 new constellations to guide his illustrations. Use the questions and prompts below to analyze of Bayer’s 49th map.
Chart of the South Polar Sky in Uranometria, Johannes Bayer, 1603, printed book. Mount Wilson and Las Campanas Observatories. The Huntington Library, Art Museum, and Botanical Gardens. 487000:0362
Questions & Prompts
Bayer included the names of the constellations on the map. Can you identify the names of any of the constellations? Are any of them familiar to you?
How is this map different than the 48 northern hemisphere maps? How is it similar?
What information do you think Bayer learned from the European explorers’ descriptions?
What information do you think Bayer didn’t know? What questions might he have had?
References and Resources
Boston Athenæum. 2014. “Uranometria.” Accessed May 3, 2022. https://www.bostonathenaeum.org/about/publications/selections-acquired-tastes/uranometria.
Brashear, Ronald, Daniel Lewis, and Owen Gingerich. 2001. Star Struck: One Thousand Years of the Art and Science of Astronomy. San Marino, CA: The Huntington Library in association with the University of Washington Press, Seattle.
Encyclopaedia Britannica. n.d. “Johann Bayer: German Astronomer.” Accessed May 3, 2022. https://www.britannica.com/biography/Johann-Bayer.
Kanas, Nick. 2019. Star Maps: History, Artistry, and Cartography. Switzerland: Springer Nature Switzerland.
Warner, Deborah Jean. 1979. The Sky Explored: Celestial Cartography, 1500-1800. New York: A. R. Liss.
