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Transcript
Also known as "Star Islands".
A massive, gravitationally bound system that consists of stars, stellar remnants, gas, dust and dark matter..
There are about 170 billion galaxies in our Universe.
Together, they all have more stars than there are grains of sand on earth.
Galaxies
Types, formation and evolution
Galaxy formation
The first galaxies were formed a billion years after the big bang.
They may have been formed out of collisions and mergers between clouds of gas that were scattered around in space.
Collisions between smaller galaxies produced larger ones.
Today, the process continues to produce even larger galaxies.
Types of galaxies
Hubble's tuning fork
Our own galaxy
The milky way
Some facts:
- Constitutes of 200 billion stars.
- 100,000 light years in diameter.
- 2000 light years thick.
- Part of the local group along with 29 other galaxies
- Part of the local supercluster along with other galaxy clusters like Virgo, Leo and many more.