The Moon can be visible in different forms, depending on angle between viewer, the Moon and the Sun.

The Moon can be visible in following phases in order of their apperance in time:

   * New Moon         - Moon is black circle, invisible to observer.
   * Waxing crescent  - Moon is little crescent, angle (see above) is very big.
                        It looks like )
   * Waxing gibbous   - Moon is visible as semicircle.
   * Full Moon        - Moon is visible as circle.
   * Waning gibbous   - Moon is visible as semicircle, 
                        but on the contrary as at waxing gibbous.
   * Waning crescent  - Moon is visible as little crescent, 
                        but on the contrary as at waxing crescent. 
                        It looks like (

You can know a current stage of the Moon by command 'phase'.