Answer:
There will always be a shadow created by the sun shining on the moon.
When the earth is in this shadow the result is a solar eclipse,
If an observer on earth can see none of the sun then this is called a total eclipse of the sun, otherwise it will be a partial ecliplse of the sun.
Note: A solar eclipse can only occur during a "new" moon at which time the moon is not visible to an observer on earth because of the light of the sun.