The word galaxy is from the Greek root galaxias [γαλαξίας], literally meaning "milky", a reference to the Milky Way galaxy.
The observable universe alone may contain 170 billion galaxies.
Typical galaxies range from dwarfs with as few as ten million stars, up to giants with a hundred trillion stars.
Galaxies are classified into 3 main types: elliptical galaxies, spiral galaxies, and irregular galaxies.
Dark matter appears to account for around 90% of the mass of most galaxies.
The larger galaxies contain over a trillion stars.
The largest galaxies in the Local Group are the Milky Way and the Andromeda Galaxy.
The Milky Way galaxy appears to harbor one supermassive black hole within its nucleus.
The Large Magellanic Cloud, a satellite galaxy of the Milky Way, is 170,000 light years away from Earth.
Number of Stars in Average Galaxy: 40 billion.
There are an estimated 400 billion stars in our Galaxy, the Milky Way.
It takes the Milky Way galaxy 250 million years to complete one rotation.
