Masters of the Stars: Ptolemy

Our interest in the stars and the universe is not new. From the beginning of mankind have we been looking up our night’s sky wondering what all those celestial bodies represented. In very early civilisations, the Moon, Sun, and stars were identified to gods and religious spirits. Today, we still find traces of early astronomy dating back as far as Mesopotamian times, more than 5000 years ago. But in the entire recorded history nobody has been as important for astronomy and astrology as Claudius Ptolemy. This scientist lived in Greece during the Roman era, about 1900 years ago. Today we still use a lot of his work and his star mapping, and other astronomers have used his theories to prove their own researches. So let’s have a look why Ptolemy was such a big fish for our knowledge of stars and constellations.The-Great-Ptolemy---master-of-the-stars-underluckystars

Ptolemy named more than half the constellations

There are 88 constellations in our sky. Out of those, 48 of them were named by Ptolemy. This does not mean that he created them all, some were already around from previous civilisations. But most of the 48 star signs with his signature, were actually created by him. All the zodiac signs, the ones that determine your horoscope, were also named by Ptolemy. And he recognised the astrological value to the star signs as well.

In one of his popular works, the Tetrabiblos, Ptolemy mentioned that besides a person’s upbringing, race, and country of birth, the position of the stars, the Moon and the Sun also influence the personality of a person. So Ptolemy acknowledged that astrology existed and worked, but also admitted it should not fully be relied on.

The movement of the stars

Besides the 4 piece, Tetrabiblos, Ptolemy published another important treatise. It is even considered his masterpiece and it’s called the Almagest. In the Almagest, Ptolemy describes the orbits of the planets and the motions of the stars. According to Ptolemy, the Earth was dead still in the center and the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, and the stars moved around it in set elliptical movements.
There were some very interesting discoveries in Ptolemy’s work. He mentioned the Earth being a sphere. Legend says people didn’t know the Earth was a sphere until the Renaissance, but this is clearly untrue. He also described the universe being a spherical object, explaining the orbits of the celestial bodies.

For more than 1200 years, astronomers in the Western world considered the Almagest the leading publication regarding celestial bodies and their movements. It wasn’t until Copernicus that people started doubting the theories of Ptolemy. The biggest problem Copernicus had with the Almagest was that it considered the Earth at the center of the universe. Ptolemy saw the orbits of the planets and stars pretty well, but failed to recognise the Sun as the center of our solar system.

So Ptolemy and his publications weren’t perfect. But as they were written 1900 years ago, and there were no tools like the ones we have today, it is still very impressive what he has done to both astronomy and astrology.

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