Answer:
After 29.5 days
Step-by-step explanation:
Complete question
If the moon started its orbit from a spot exactly between Earth and the sun, then after how much time it would return to almost the same spot ?
Solution
New moon occurs once in 30 days. Hence there is a gap of 30 days between two new moons. To be specific moon phases repeat after every 29.5 days. However, as per the Gregorian calendar there can be two new moon in one month with a gap of 15 days only between two new moons.