Origin and history of constellations

On the night sky in clear weather, thousands of stars of different brightness and colors can be observed flashing in the darkness. In ancient times, our ancestors would link the stars with various legends and myths, which eventually lead to establishing constellation in many civilizations such as Greek, Roman, Egypt, more and more.

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.

Modern constellations

Many people would be confused when some constellations had several different names and belonging to different groups of constellations in different countries. Solving this confusion was one of the major reason of the establishment of unifying different understandings to be 88 constellations in 1930 by IAU.

Trio of suns: Riger Kenttaurus

Riger Kenttaurus (or called Alpha Centuri) is the brightest star in the constellation of Centuri viewed from the solar system. and the third brightest star in the night from Earth. For a long period of time, it was misunderstood to be one star or dazzling double star. But with the improvement in instruments for astronomy, it was finally revealed that Riger Kenttaurus was made up of three stars, which is quite rare among the stars discovered in the universe. In most case, larger object(s) will engulf smaller ones in the early age, and it is a rare case that three stars of different masses can continue to exist and maintain a balance among them.
In comparing the absolute brightness of stars, Riger Kenttaurus is not ranked very high. The main reason of why it is the third brightest in the night sky is that it is the star closest to our solar system (around 4.2 lightyear).
Being the closest star (sun) to us away from the solar system, Riger Kenttaurus is widely used in SF stories, novels and movies around the world.

Monoseus: Constellation of the legendary unicorn

Monoseus - another legend of unicorn

Constellation of Monoseus is situated between two hounds in the night sky: Canis Major and Canis Minor. Its existence was defined by the astronomer Petrus Plancius in 16the century.
Comparing to its shinning and obvious neighbors, Monoseus mainly consisted of stars which are less obvious and hard to find. The presence of a rose nebula makes it even less prominent.

Legends of Monoseus from different sources

Monoseus is a Greek word. In English, this legend creature is generally known as Unicorn.
Unicorn is a legendary creature beginning from Greek legends with an outlook similar to a horse but with a horn in the center of its forehead. It has a ferocious nature and can only be calm by the hug of a virgin. Besides the horn, unicorn also has several characteristics like a tail of a lion, beard of a male goat, and eyes in ocean blue color. Its horn is said to have magical power, and can purify all toxic and polluted waters to be clear and harmless again, showing its symbolic deep relationship with power of water.
Unicorn has existed in Old testament bible and part of it has been inherited by the bulls nowadays.
There were also some more detailed descriptions about unicorn as real organism, the most famous one was from Ctesias, a doctor and historian in Greece in around 400 B.C., when he was working as a doctor for King Artaxerxes II of Persia. He said he had come across unicorn in his trip to India. However, no description or proof can be found that he had actually been there and it was still a mystery whether his foundings is true or not.
Unicorn was also worshipped by ancient Celt before the spread of Christianity in Northern Africa. Some historians claimed the different tales and myths of Unicorn in various cultures are indeed combination and mixing of various legends, a by product of development of cultures.

Star of longetivity: Canopus

Canopus (Carina α)

Canopus is the second brightest star throughout the day, only slightly dimmer than Sirius.

Canopus in different cultures

In Egyptian legend, when ancient Egypt was destroyed by huge flooding, the gods Isis and Osiris were on a huge argo (the so called Noah's Ark mentioned in the bible of Christianity).
According to the myth of Babylonians, the argo was created by the God Ea after realizing the desperate and fear from the humans.
The description and story of this argo vary for differnt civilizations and culture towards different gods/godesses.
For the ancient greeks, the vessel was the place where lots of heros grouped together sailing across the oceans. Canopus was shinning at the Argo's tail.

Canopus has the meaning of the hermit for giving guidance, and is the brightest star in the constellation of Argos. In the view from earth, it is the 2nd brightest star in night sky just slightly dimmer than Sirius. This star is visible in Southern hemisphere of Earth, but can only be seen by southern part of Northern hemisphere. For example, it is not visible to northern part of China.

In ancient China, it paid an important part in legends as it represents the old hermit of the south pole. The star is regarded to be symbol of longetivity, peace and fortune. Appearance of Canopus is regarded to be a peace and forture sign (which is a contrary to Sirius). However, the star is situated too south and it can only be seen from southern part of China (In ancient China, these regions are mostly uncultivated regions). It is impossible to observe it from Northern China (the centre of China in ancient times). This characteristic is one of the reasons why it is called "Antarctic Canopus (i.e. "Nanjixianweng") in ancient China.

The image of Antarctic Canopus (Nanjixianweng) is an old hermit with high forehead, long elbow, holding hands with a large peach. It symbolise peace, harmony and statue of Nanjixianweng is one of the precious present for birthday for the riches.

Canopus is in the brightest star in Carina which can be seen in southern hemisphere. It is believed the English name (Canopus) is named after the Greek army expedition to Troy. Comparing to Sirius, Canopus is much far away from Earth and it is difficult to calculate its distance form the Earth. Most astronomers (before modern space age) suggested it is situated 1,200 light years away. However, with the modern telescopes, it is noted that Canopus is actually 700 lightyears from us, and it is the largest star within a radius of 700 lightyears from us.

Major stars in the night sky: Sirius

Brightest at night of Winter: Sirius (Canis Major α)

It is the brightest star at night during winter in north hemisphere (Apart from members of solar system). The magnitude of brightness is -1.45 which is 23 times of our sun. The main star is a blue colored star with the size of 1.7 times of our sun.Surface temperature of Sirius is very high - 10,000  ℃ which is twice as the sun.

Sirius has existed in the ancient history of Egypt, and its appearance is regarded to be the sign of Nile Delta flooding. So the star is regarded to be a symbol of fertility for Egyptians. For other cultures, it is a bit different. e.g. ancient Chinese regard Sirius as a star of disasters and bad interference. It symbolize alone and separate.

The name of Sirius is originated from Greece, meaning “burnt" or "hot weather”. It is because when Sirius is visible in early summer each year (also in northern hemisphere), usually it will be overlapped with the sun, and it is why it is regarded to be a source of heat.

In 1844, German astronomer Bessel discovered that Sirius is indeed a binary star (two stars revolving each other, instead of one single large star), according to the wavy revolving pattern of Sirius. The companion star is first observed by American astronomer A. Clark in 1862 with the use of a caliber 4.7M refracting telescope which is the largest at that time. The revolving cycle of The two stars is 49.9 years.

Mass of this companion star is similar to our sun but the diameter is much shorter (only 1/50), and it is the first white dwarf actually observed by astronomers.

Sirius is also called the Canis Major α and it has an important role in the ancient legends and myths of constellations. It is one of the stars of the Triangle in Winter (Le Triangle d'hiver, together with Betelgeuse and Procyon) and is probably the first star that most people come across in learning to view stars.

Because Sirius is so bright, basically no specific instruments will be required in observation. Of course, it is much better for viewing the stars in the rural areas away from cities. One more tip is, you should arrive at the site of observation at least 45 minutes in advance, so there is time for your eyes to adapt to the darker environment. You can bring a torch with you but please kindly be reminded not to use it too frequently, and there is no need for any sunglass or telescope.

Sirius - related legends

It is a legend spreaded among the Dogon people in Mali, Western Africa.
The tribes were traditional tribes of black people in Western Africa, believing to have been , their culture was not advanced in most circumstances, except in the category of knowledge in astronomy.It is somewhat impossible for people to have get such high level of astronomy, without even the most basic telescope for observing the universe. For example, they already know Sirius is indeed a binary stars (consists of two stars evolving each other), and Sirius β had a orbital period of around 50 years. This second star of Sirius was not discovered by scientists until late 19th centuries. How can a ancient, less developed tribes get such knowledge hundreds of years in advance?
In their local legend, the knowloedge from the star Sirius β was from a God named "Nuomo", who had come across with their ancestors long long time ago.Dogon people had an ancient picture, showing their God was travelling on a huge space (believed to be space craft) dragging a long long tail of flames. He landed from the sky, and taught various knowledge to the Dogon people.