Uranometria

Part of speech: noun

Definitions

1. A detailed celestial atlas created in the 17th century to map constellations and stars in the night sky
2. An old star map compiled to chart the positions of celestial bodies for astronomical reference
3. A historic astronomical chart used to identify and illustrate the arrangements of stars and constellations

Etymology: "Uranometria" is the older form of "uranometry", the measuring of the heavens, and in the sense of a star atlas it was once a standard term for a book of charts. The first part comes from Greek "ouranos", meaning sky or heaven, which is also the root of "uranium", named after the planet Uranus, itself named for the Greek sky god. The second part is "-metry", from Greek "metron", a measure, the same ending found in "geometry" and "thermometer". Put together, the word literally means "sky-measuring", a name that fits a time when mapping the stars was a matter of careful observation and calculation rather than simply drawing pictures. The sense of a book of star maps is the older and more specific use, which is why the word now appears mainly in historical discussions of astronomy.