GALAXIES…

…are huge collections of gas, dust, planets and hundreds of billions of stars held together by gravity.

GALAXY SHAPES

ELLIPTICAL SHAPE

• spheres or ellipses• larger galaxies with some of the oldest stars

GALAXY SHAPES

SPIRAL SHAPE

• large central bulge with lots of stars• appears to have long arms spiralling out from centre

Top View

Side View

GALAXY SHAPES

IRREGULAR SHAPED

• no regular shape or pattern

OUR GALAXY – THE MILKY WAY central bulge(contains globular clusters – 100 000 to 1 million stars)

spiralling arms(contains open clusters – 50 to 1000 stars)

100 000 light years across

We know how big the Milky Way is by measuring with radio waves

The Milky Way

• Might see it on clear nights far away from cities.• Star clusters can be found in the Milky Way. They are a

collection of stars held together by gravity. Two types: – Open clusters: 50 to 1000 stars, found along the main band of the

Milky Way– Globular clusters: 100 000 to 1 million stars arranged in a distinctive

spherical shape in the centre of the Milky Way

OUR UNIVERSEWe know there are billions of galaxies across the universe. But where didthese galaxies come from?

CREATIVE ASSIGNMENT – ``The Origin of Our Universe``

In groups of 3 or 4, you are to come up with a theory as to how the universe started. In your theory you must address how, when and wherethe universe was created. Try to make your theory scientific andbelievable. Put your theory on a piece of chart paper using words and pictures. You group will present the theory to the class trying to convincethem that your theory is correct.