Galaxies (4:11)

 

Our observable universe (the one we can detect with today's equipment) consists roughly of 100 billion galaxies with each galaxy consisting of about 100 billion stars.

Galaxies are made up of normal matter. By mass, galaxies are 10% shining stars and 90% free floating hydrogen gas. However the bulk of gravity that is required to hold the stars in rotating galaxies from flying off seems to come from Dark Matter.

 

 

 

 

 

 

 

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