Ancient Astronomy



Approx. 400 BC

The ancients of Greece and Babylon record the risings and settings of stars on parapegma (which is kind of a calendar) to help them record the time of the day and the year.

Hicetas of Syracuse explains apparent motion of the fixed stars by the Earth spinning on its own axis.

Archytas of Tarentum did “Gedankenexperiment” which is a mental experiment mostly used by physicans in that time. Just with that simple experimeny he assumes that the Universe is infinite.


Approx. 350 B.c - 335 B.c

Aristotle wants to confirm that celestial bodies are spheres. He also used a number of proofs that the Earth is a sphere, including the observation that its shadow on the Moon during lunar eclipses is always a circle.

Planetary Theory and the Geminus of Rhodes

134 B.c - 100 B.c

Planetary theory-is the motion of the sun, which explains the irregularity of the seasons and the uniform circulation motion of the sun.

Geminus- Astronomer, Mathematician, writes that the Earth is a sphere, the sun and the stars are spheres of fire from the same material, there are infinite number of stars, the Moon

Julius Caesar and the Calendar

46 B.c

Sosigenes of Alexandria designed a calendar of 365.25 days which was introduced by Julius Caesar. He made his own calendar called the Julian calendar but was betrayed and killed in the Senate by those dissatisfied with his rule.

The Introduction of the Phenomena

Approx. 50 A.D

Geminus (Greek astronomers) wrote an elementary textbook called an Introduction to the Phenomena. It contains, general information about the practice of astronomy.

Marinus and Cleomedes

Approx. 100 A.d

Marinus- one of the first scientists to use longitudes and latitudes in his work. He did not use them as extensively as Ptolemy in his analysis of the Phenomena.
Cleomedes also wrote an introductory book on astronomy. He entitled it On the Elementary Theory of the Heavenly Bodies. He references the work of Posidonius and Eratosthenes and generally presents the work in the frame of Aristotelian physics.

Theon of Alexandria

300 AD

Despite the astrolabe having been in use for many years, Theon writes history's first definitive treat on the astrolabe. It does not survive today but is referenced in later works.
*astrolabe-is a very ancient astronomical computer for solving problems relating to time and the position of the Sun and stars in the sky.

Chaucer on the Astrolabe

1300 A.d

The oldest, surviving, English scientific work surfaces in the form of a Treatise on the Astrolabe. The famous Chaucer wrote it for his ten year old son, Lewis.

Georg Hartmann

1489 A.d

Georg Hartmann is born and grows up to be one of the most celebrated astrolabe makers of the Renaissance. Aside from making fine ones for royalty, he also made cheap astrolabe kits for people of lesser means.

The quadrivium

Approx. 1600 - 1700

the teachers of astronomy in Britain were, in the main, clerics with an interest in proclaiming the glory of God and teaching the ‘quadrivium’ (the four classical subjects of arithmetic, harmony, geometry and astronomy, knowledge of which made a man educated in science). Modern knowledge such as Copernicus’ and Kepler’s explanations of the motions of the planets and Galileo’s theory of dynamics were taken up by amateurs outside the established educational professions.