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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.
