Following part 1 of Brian’s article posted on the 20th July, he looks at the necessary properties of the particles which make up dark matter.
- They must emit no light.
- They must be cold.
- They must interact weakly with ordinary matter.
- There must be a massive quantity of them.
Brian then offers three leading candidates based on current theories, but so far we just don’t know what it is. Please go to www.oneminuteastronomer.com/10251/lazy-guide-dark-matter-2/ to read more.