The Legacy of the Milky Way

If you are fortunate enough to live in an area which has dark skies – far from light pollution – you will likely have noticed the faint band of light in the night sky we call the Milky Way. To us- it is home to our fellow planets and the Sun we orbit. The Milky Way is visible in the night sky all year round but Summer is especially a great time to go out and view it. And once you've looked at it you can easily see how many of our ancestors saw it as a river in the sky.

To the ancient Egyptians – it was the celestial version of the river Nile – and the pathway to the next life. The Yakuts of Siberia referred to the Milky Way as God's footprints.

The Osage Indians of America thought the Milky Way to be the pathway for the souls of the dead to pass along until they found a star to reside upon.

To the ancient Chinese, it was “Tian Ho” the celestial counterpart of the Ho, or Yellow River. The Chinese also saw a connection between the seasonal rains and the Milky Way. Their dry season was during the winter which also happened to be when the Milky Way was thinner and less dense in the sky. And during summer, the rainy season, the Milky Way was much wider in the sky – like a swollen river.

There is an old story from China, dating back to the early Zhou Dynasty around 700 BC which tells how the summer rains played a part in a love story between the weaver maid and the cowherd.

In this image, the Milky Way passes through the summer triangle. Altair is the bright star in the lower right. Vega is the bright star in upper middle. The third star in the triangle is Deneb (lower left) in Cygnus.
Summer
The characters in this ancient celestial soap opera are Altair – the brightest star in Aquilla which represents the cowherd: Vega, the brightest star in Lyra, which represents the weaver maid, and the Milky Way which represents the River Han in Heaven.

Our story begins along the banks of a stream where the cowherd is watching his water buffalo cow. Suddenly, seven celestial maidens appear for a dip in the Earthly stream. The maidens certainly catch the attention of our cowherd but he doesn't know quite what to think about them – so, according to the story – his trusty buffalo cow fills him in. She explains that the maidens are celestial weavers who spin the thread for the clothes worn by the gods in heaven.

The cowherd is particularly moved by the youngest of the maidens and the buffalo once again offers advice. She tells him that if he steals the robe worn by the maiden, she would not be able to return to heaven. and would have to ask the cowherd for help. This would play right into what he wanted – because according to Chinese tradition – if a woman is seen by a man while in the buff – they would have to be married. The cowherd follows the buffalo's advice and soon the couple are married.

For three years they enjoyed wedded bliss on Earth, and produced two children. But in heaven – trouble was a-brewing. It had not escaped the notice of the Queen Mother of the West that heaven was short one weaver. Queen Mother was also the grandmother of the young maiden and one day when the cowherd was away – grandmother summoned the maiden back to Heaven and ordered her to work.

Our cowherd then returns home to find only the two children at home and he was clueless as to what to do. Fortunately, the old buffalo cow is there to fill him in. She explains that she will die in a few days, and the cowherd should take her skin and hide himself and the children inside and she will carry them up into the sky.

The two lovers have a lusty reunion in heaven but soon grandmother notices the girl's loom is once again unoccupied. Now grandma is really ticked and decides to make an example of the couple for other maidens who might get ideas. Grandmother draws a line between the couple in the sky and creates a celestial river – the Milky Way with the cowherd (Altair) on one side and the maiden (Vega) on the other.

Separated by the river, the two lovers grieve for each other, and while Grandma couldn't have cared less – their plight did move the heart of the King of Heaven. He decides to allow the family a short and conditional unity. On the seventh night of the seventh month they may be reunited if the world's magpies will create a bridge over the river. To accomplish this, there must be good weather.

In the Chinese calendar, the seventh day of the seventh month usually falls in August, and the end of the rainy season and beginning of Autumn. So the celestial odds are in favor of the family. It also occurs during a time when the Milky Way is high overhead and the stars representing the family, Altair and Vega, are visible.

We believe our galaxy looks similar to this galaxy, NGC1300.
Similiar Galaxy NGC1300
While our ancestors thought the Milky Way was some sort of celestial river, we know that it is a spiral galaxy, and our home in the cosmos. The Milky Way is 100,000 light years across and contains about 200 billion stars! As galaxies go – ours is a huge one – and is estimated to be between 750 billion and one trillion solar masses.

Milky Way edge on. Globular Cluster M12 Cluster in Hercules
Seen edge-on, our galaxy would look similar to this. Globular cluster in Centaurus NGC5139. M12 is a globular cluster in the constellation Ophiuchus. Globular cluster in Hercules.

There are several fairly distinct parts to the Milky Way. The halo and central bulge have a lot of old stars and globular clusters. Globular clusters are clusters containing ten thousand to a million older stars gravitationally bound.

Clusters of Pleiades M8 M17 Orion Orion Nebula detail diffuse nebula in Carina The Triffid nebula
Perhaps the best known of the open clusters are the Pleiades. Diffuse nebula M8. Diffuse nebula M17 in Sagittarius. Well known diffuse nebula in Orion, M42. Details of the Orion nebula. Diffuse nebula in Carina. The Triffid nebula, M20 is also a diffuse nebula.

The disk of the galaxy contains mostly young stars in open clusters, along with gas and dust. Open clusters are groups of stars physically close and held together by gravitational attraction. The clusters begin in clouds of diffuse nebulae where star birth begins to take place.

We refer to the Milky Way as a spiral galaxy, but more recent data has shown that more specifically, our galaxy is likely what is called a barred spiral.

Our Sun and planets are located about 27,000 light years from the galaxy's center. We reside approximately 600 light years from the inner edge of the Orion arm and only 20 light years above the equatorial plane.

The Milky Way belongs to a group of galaxies called the local group, containing three large and over 40 small galaxies. It is the second largest galaxy in the group, the largest being M31, the Andromeda galaxy (the most distant object visible to the naked eye.) M31 is about three million light years away.

HST images the Large Magellanic Cloud.
Large Magellanic Cloud
There are some dwarf galaxies in the local group which are actually satellites of the Milky Way. The best known (and also visible to the naked eye in the southern hemisphere) are the Large and Small Magellanic Clouds.

A time exposure image of the Milky Way in Sagittarius.
Time Exposure of Milky Way
We see a different view of the Milky Way each season of the year. The summer Milky Way is the brightest view and at this time you can see the feature called the Great Rift. This rift is a dark band running between Cygnus and Scutum created by a group of dense interstellar clouds blocking the light of stars behind them. The summer Milky Way rises in the north and runs high across the sky through Cygnus and Aquilla and across to the southern horizon where we look directly toward the center of the galaxy in Sagittarius and Scorpius.

The Autumn Milky Way is also high overhead but it lacks the bright objects of summer. It comes above the northeastern horizon in Auriga and Perseus, passing overhead through the stars Cepheus and Cygnus and passes below the southwest horizon through Ophiuchus and Sagittarius

The winter view of the Milky Way is higher in the sky and we are looking away from the galactic center, out towards the edge of the Orion arm, named after the constellation Orion whose stars reside here. The Orion arm contains younger brighter stars. During winter, the Milky Way runs from northwest horizon in Cepheus and Cassiopeia, high overhead through Perseus, Auriga and Taurus, and over to the southeast horizon near Canis Major.

With the spring view of the Milky Way, we are looking above the galactic disk. These skies have less bright stars and the few stars which are bright, such as Arcturus, are bright because they are physically close to us. In the night sky, the Milky Way will rise in the northern horizon in Cassiopeia and Perseus. It will swing low across the western horizon through Gemini and above Orion and pass under the southern horizon.

You do not need binoculars of a telescope to view the Milky Way – by far the most important is a dark sky! As more and more lights pollute our night skies – and obscure more stars, fewer people have seen the Milky Way. Binoculars or telescope will resolve the hazy clouds into a myriad of stars. While astronomy books and websites can provide you with specific targets to look at – spend some time just gazing along the band of light and you will be entranced!