Galaxies and the Milky Way

In short: A galaxy is a huge collection of billions of stars, gas, dust and dark matter held together by gravity. Our home galaxy is called the Milky Way.

In more detail: The Milky Way is a spiral galaxy with roughly 100 to 400 billion stars and about 100,000 light-years in diameter. Our Solar System lies in one of the spiral arms.

In detail

• The band in the sky: We see the Milky Way as a shimmering band because we look into the disc from the inside.
• Galactic centre: A supermassive black hole sits there (Sagittarius A*) (schwarze-loecher-und-neutronensterne).
• Andromeda: The nearest large galaxy, about 2.5 million light-years away. It is approaching the Milky Way.
• Shapes: Spiral, barred, elliptical and irregular galaxies.
• Universe: There are probably hundreds of billions of galaxies (lichtgeschwindigkeit).