[Image: Hypatia by Charles William Mitchell, 1885]
I knew she was a mathematician but I didn't realize that she was also a skilled astronomer and actually collaborated with her father, Theon, on several treatises.
"It is thought that Book III of Theon’s version of Ptolemy’s Almagest—the treatise that established the Earth-centric model for the universe that wouldn’t be overturned until the time of Copernicus and Galileo—was actually the work of Hypatia." - Hypatia, Ancient Alexandria's Great Female Scholar, Smithsonian.com
It also says one of her students, Synesius, wrote that she taught him how to build an astrolabe.
The astrolabe is a very ancient astronomical computer for solving problems relating to time and the position of the Sun and stars in the sky. Several types of astrolabes have been made. By far the most popular type is the planispheric astrolabe, on which the celestial sphere is projected onto the plane of the equator. A typical old astrolabe was made of brass and was about 6 inches (15 cm) in diameter, although much larger and smaller ones were made.
[Image: Front of an astrolabe created by Frenchman Jean Fusoris. Photo courtesy of the Adler Planetarium and Astronomy Museum , Chicago, IL. The Adler Planetarium houses the largest collection of astrolabes in North America]
Astrolabes are used to show how the sky looks at a specific place at a given time. This is done by drawing the sky on the face of the astrolabe and marking it so positions in the sky are easy to find. To use an astrolabe, you adjust the moveable components to a specific date and time. Once set, the entire sky, both visible and invisible, is represented on the face of the instrument. This allows a great many astronomical problems to be solved in a very visual way. Typical uses of the astrolabe include finding the time during the day or night, finding the time of a celestial event such as sunrise or sunset and as a handy reference of celestial positions. Astrolabes were also one of the basic astronomy education tools in the late Middle Ages. Old instruments were also used for astrological purposes. The typical astrolabe was not a navigational instrument although an instrument called the mariner's astrolabe was widely used. The mariner's astrolabe is simply a ring marked in degrees for measuring celestial altitudes. - The Astrolabe, James E. Morrison.
Although principles of the astrolabe projection have been known since 150 BCE, Hypatia's astrolabes must have been among the earliest working models dating from the 4th century CE. Astrolabes were further developed in the Islamic World in 800 CE but did not make their way to Europe until they were introduced through Islamic Spain (Andalusia) in the early 12th century. Just think, if Cyril's murderous monks had spared Hypatia, Europe's knowledge of astronomy would have been advanced by eight hundred years!
