The relative positions of the Sun, the Moon and the Earth are shown in the figure given below:

 

 

 

 

 

 

What is the phase of the moon at the given position? (Consider that the white portion represents the illuminated part of the moon.)

In the given relative positions of the sun, the moon, and Earth, an observer from Earth’s surface cannot see the brighter face of the moon. Only the dark face of the moon is facing the Earth. The moon rises and sets with the sun and hence it is not visible in the night sky. Therefore, we can say that the new moon phase occurs when the moon is between the sun and the earth.