History of constellations
As defined by the The International Astronomical Union：IAU in 1930, there are totally 88 constellations now as a common understandings in the world. Before that time, people of different civilizations have their own traditions of which stars will form which constellations and the understands vary among different people.The concept of constellation was believed to be established in ancient Babylonian times, descriptions of constellations and stars were found in written records of different ancient ruins, and ancient people already believed stars and constellations to be related to certain legends.
Ancient Egypt along River Nile was another ancient civilization which was known to study a lot about stars. Due to practical reasons (an accurate calendar was needed for farming), Egyptian had paid lot of time in studying stars and their relation to weather and calendar. Egyptians also had legends of stars and constellations, and stars paid an important role to their kingdom. A good evidence is carvings of Sirius and several constellations had been found in tombs of Pharaohs.
Connection with myths
Ancient Greeks inherited knowledge of constellations from Babylonians, via Phoenicians who had engaged in tradings among Mediterranean Sea, which eventually lead to the myths of stars and constellations which we know today.We could not find absolute proof of when ancient Greek mythology began. As many scholars agreed, it was probably initiated by epic poet Homer. Afterwards, Greek bards distributed many myths and legends about constellations allover Greece, and in nearby countries, including all the coming civilizations in Europe. With the increasing connection between myths and constellations, more constellations were organized under the Greek Mythology.
Ptolemy's 48 Constellations
The people actually put together these ancient knowledge of constellations was Ptolemy (AD90 - 168), a Greek scholar in astronomy. He had set up a system of 48 constellations - 12 from Zodiac belt, 21 from northern sky and 15 from southern sky.His system of 48 constellations had been used for nearly 1,500 years, until the Age of Exploration when more and more constellations and stars were found when European voyagers travelled around the world.
More constellations from Age of Exploration
Fifteenth century was the beginning of the so called Age of Exploration, when European pioneer voyagers begin long journey to undiscovered waters, such as Africa and America, beginning trading with people in distant unknown lands. They also discovered many stars not previously discovered by either Greeks, Egyptians or even Chinese (European cultures also get information via the silk road). The newly found stars was unable to be seen in northern hemisphere. It was the time for adding supplementary information to Ptolemy's 48 constellations, which only consists of those visible in northern hemisphere.There were many scholars putting together the newly discovered stars and constellations, such as Dutch explorers Pieter Dirkszoon Keyser and Frederick de Houtman in late 16th century, Johann Bayer in his star atlas Uranometria in 1603, and Nicolas Louis de Lacaille in his star catalogue in 1756.
