If you look up in to the sky at night and are away from any light this is what you could see
The milky  way is home to at least 200 billion stars and there planets.
With a mass between 750 billion and one trillion solar masses (one solar mass=the mass of our sun), and a diameter of  100,000 light years (light would take 100,000 years to travel from one side to another) it is a massive object.
Investigations of the hydrogen clouds contained within the milky way show us that this galaxy is a spiral galaxy, there are many types of galaxy and they are usually categorized by their shape as elliptical irregular or spiral.
Nearest intergalactic neighbour, a small galaxy currently interacting with our own  on the other side of the milky way all though we don't know what effect it has had on the planet earth yet.
Our galaxy has a disk form when viewed from the side (above right), which is 100,000 light years across and 1-2 light years thick, in the centre of the disk lies a thin layer of  gas and dust. The galaxy has a spiral shape when viewed from above (above left).  It  also contains a central bulge or nucleus where a large black hole may be contained. The sun lies in the spiral arm named orion.



The milky way contains light from a huge number of individual stars including the sun. Dark patches in the galaxy  are made up of clouds of dust which give off no light. globular clusters can stretch out for over 130 000 light years. Contained in the nucleus  are old orange and red stars. packed in thousands of times closer than the sun is to its nearest neighbour. The central nucleus is the oldest and most densely packed part of the  milky way. Constantly turning the sun takes 250 million years to fully orbit once travelling at 250 km per second.

Above left: a diagram of the old red and yellow stars contained within the central bulge of the galaxy.
Above right: a diagram of the milky way with the corona of various matter surrounding it.

The galaxies spiral arms are temporal structures, changing shape all the time. matter can pile up here but it dosnt move with the rest of the galaxy.
The galaxy is surrounded by a  huge corona stretching out in to space containing various debris and matter. This means that the galaxy may actually be five times the size that we think it is at the moment.

The spiral arms of the milky way are named after the constellations that are scene in that part of the sky. We are located in the orion arm, but their is all so  a perseus arm, a cygnes arm, a carind arm and one unnamed arm.


A View of the milky way (The sky around the star deneb) from the northern pole (left).   And a view of the milky way from the south pole.

If you look at the constellation cygnus the swan at night you will be looking at the most densely populated area of the sky. Galieo, found the milky way  and found that it was made up of a mass of  stars apparently crowded close together. He was the first astronomer to notice this. William Herschell made the discovery that the percentage increase is greater for fainter stars, faint stars were unexpectedly plentiful near the milky way and so Herschell concluded that the galaxy must be shaped like a double convex lens.


Above:  A picture of  Galileo Galilei and William Herschel.

The milky way is called this because it resembles a faintly luminous band that stretches across earths sky at night, so ancient astronomers called it the milky way because it was a faint milky streak in the sky.

This diagram shows a picture of the milky way, With the positions of the sun and the dwarf galaxy currently merging with the milky way (SAQ DEG).


The milky way lies with thousands of other galaxies within the universe.  How was it all created?

15 billion years ago the universe began.

                   When the universe was

                  I N F I N E N T L Y

                                                                                  The universe was packed into a space of an atomic nucleus. Unimaginably hot and dense.

This molecule exploded and within a fraction of a second was expanding rapidly. Particles of matter were created and the universe expanded from the size of an atom to the size of the earth in a brief flash. There was a mix of energy and exotic particles such as quarks and anti quarks.
There was a steady rate of expansion and the temperature fell. Before the universe was one tenth of a millisecond old protons and neutrons formed, its temperature after one second was 10 billion degrees. Two billion years after the formation of the universe galaxies began to form. Our galaxy formed around three billion years after the big bang that created the universe. Our galaxy started as a huge sphere of gas which eventually settled into a compact disc form around the central bulge of denser matter.

Spiral arms formed as the galaxy  spins. Early collisions between galaxies were common  and can induce spiral arms to grow. This could eventually happen to us and our nearest large neighbour Andromeda.

This is a picture of possible galaxies behind the milky way.


There are many types of spiral galaxy shown in this picture, some have a central bulge like our galaxy and others have a bar in the centre with very few spiral arms.


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