Download File - The World of Astronomy

Astronomy for beginners
Galaxies
By Aashman Vyas
What are galaxies?

Galaxies are incredibly huge collections of stars,
dust and gas. They usually contain several
million to over a trillion stars and can range in
size from a few thousand to several hundred
thousand light-years across. There are hundreds
of billions of galaxies in the universe. Galaxies
come in many different sizes, shapes and
brightnesses and, like stars, are found alone, in
pairs, or in larger groups called clusters
Types of galaxies
There are many different types of galaxies:
 Spiral
 Elliptical
 Irregular
 Barbed spirals
 Etc.
 But I will be concentrating on the first three
since they are the main types of galaxies

How do elliptical galaxies form?
Scenario1
-Two spiral galaxies collide
-Their Super-massive blackholes merge with
each other (see my blackhole PowerPoint)
-Disturbance + collision disrupt spiral arms
of galaxy merging them
-New galaxy has rings instead of arms
-Elliptical galaxy
How do elliptical galaxies form?
Scenario2
One spiral galaxy
 Lots of satellite galaxies bombard spiral
arms
 They disrupt spiral shape
 Arms become rings
 Elliptical galaxy

How do irregular galaxies form?
Simple answer:
 When any type of galaxies collide and if
the result doesn’t have a particular shape
it is a irregular galaxy

Bibliography
Ask an astronomer (for kids)
 Wikipedia
 Yahoo answers
 Astronomy.com
 Ask the van
 The big book of stars and planets by
Robin Kerrod

Thank You For Watching