 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Galaxies |
|
|
|
There may be about 100,000,000,000 galaxies in the whole Universe. Most are grouped together in clusters of galaxies. Large galaxies may have up to ten times as many stars as our own. All galaxies are spinning as they move through space.
Galaxies have various shapes. Elliptical galaxies are shaped like lemons. Some of these are very rounded, whilst others are flattened. Irregular galaxies have no clear shapes. They are mostly small. Spiral galaxies have curved arms, like our own Milky Way Galaxy.
Barred spiral galaxies have a straight band of stars across the centre, which links curved arms. The nearest large galaxy to our own is great spiral in the constellation of Andromeda. It can just be seen with the naked eye. It is 2,200,000 light years from Earth. Most galaxies seem to be about 12,000,000,000 years old. |
|
|
|
What is the Milky Way ? |
|
|
|
If you look at the night sky, you will see a hazy band of light. This is called the Milky Way, and it is made up of countless stars. OurSun is just one star in this vast group, or galaxy. There may be over 100,000,000,000 stars in the Milky Way Galaxy. It is about 100,000 light years from one side to another and 10,000 light years thick. |
|
|
|
What shape is our galaxy ? |
|
|
|
Viewed end on, the Milky Way Galaxy is shaped like a discus. It is thicker at the centre than at the edges. An overall view shows the galaxy as a huge spiral, like a Catherine wheel firework. The whole galaxy is moving through space. It spins once every 225,000,000 years. |
|
|
|
 |
|
|
|
 |
|
|
|
|
|
 |
|
 |
|
|
|
|
|
 |
|
|
|
|
|
 |
|
|
|
table of content |
|