Galaxies

It is now thought that at the heart of each galaxy is a super-massive black hole. When matter falls onto this black hole, it liberates vast quantities of energy enabling the galaxy to be seen from great distances. Such galaxies are known as quasars and they are some of the most remotest objects in the universe. Some quasars align with seemingly nearby galaxies, these are known as Arp Pairs (or Arp galaxies) after Halton Arp who first pointed them out. According to Arp, this disproves the Big Bang Theory - but most astronomers believe they are just chance alignments.

Galaxies are composed of stars, nebulae and dark matter. They take on various shapes

• Spiral Galaxies
• Elliptical Galaxies

The Sun is a member of a galaxy known as the Milky Way.

Stars, Nebulae and Dark Matter

• Stars - almost spherical bodies that generate light and other energy.
• Nebulae - vast clouds of dust and gas that can only bee seen by reflecting the light of neighboring stars, or they may be 'seen' as a dark cloud silhouetted against a bright background.
• Dark Matter - non-luminous bodies that can not be 'seen' but whose gravity may have an effect of neighboring stars and nebulae.

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