From largest to smallest they are: Universe, galaxy, solar system, star, planet, moon and asteroid.
The inside of this cycle provides more meaning for a half moon and a half sun. Often the Sun is seen as a symbol of renaissance, power and strength. In many cultures the moon is often associated with the woman as a goddess.
<em>Hope this helps!</em>
Because they all have different densities. If you have milk and peanut butter in different bowls the milk will be a lot easier to get off than peanut butter because of the density dofference. Does this help at all?