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Ancient Greek Astronomical Tools

Telescopes and computers are common astronomical tools in ready use today. The ancient Greeks, however, did not have the luxury of modern science. They instead relied on several complex yet ancient tools for studying the stars, any of which were influenced or innovated by the famous Greek astronomer Hipparchus. The tools had the same aims as tools of today -- namely, seeing the sky and the stars, and coming to understand celestial movements -- but were generally much more rudimentary. In many cases, though, they were just as precise.

Astrolabes
- Some astrolabes were more complex than others.
  
  Astrolabes, which in Greek mean "star takers," came in several different forms and were used to find the position of the stars during certain points in the day. Astrolabes could also be used to predict star positions and tell the time. The instruments were first developed around 150 BC and were typically composed of two discs that showed the stars in the sky. A movable arm or several arms could be positioned to correlate to a specific date and time, moving one disc. The stars on the second disc after the time was entered correlated to that time's star positions.
Armillary Sphere
- Armillary spheres were complex devices and used primarily to predict celestial movement.
  
  Armillary spheres used several rings called armillirae to represent astronomical cycles. Complex armillary spheres incorporated more rings than simpler spheres, and many even included celestial markings on the rings for greater accuracy. The rings were set to spin and mimic the movement of celestial bodies like the moon or stars. Early astronomers could properly set the rings of the armillary sphere, then line it up with a given celestial body to accurately predict its movements.
Quadrants
- This artwork depicts the Greek astronomer Ptolemy using a quadrant.
  
  Quadrants were not perfected until the medieval period, but they were originally invented by the Greeks, who referred to them as "plinths." Quadrants were plates that showed approximately one quarter of the sky. They were used to measure the movement of stars across the meridian. Early Greek quadrants were often large, and were known as "mural quadrants." Portable quadrants became popular in the 1800s, especially with sailors. These tools were was replaced by the sextant, a similar but more modern tool for using stars for navigation.
Antikythera Mechanism
- The Antikythera mechanism was discovered in 1901 by divers off the island of Antikythera. The 2,000-year-old device looks like an ancient clock with an array of gears and dials. The mechanism has characteristics that resemble the workings of an ancient computer with designs advanced enough to match a 20th century watch. The device is speculated to have been used to accurately predict the motion of the stars and other celestial bodies by simply turning a dial.

Astronomy