Final answer:
The new calendar day begins at the International Date Line in the Pacific Ocean.
Step-by-step explanation:
The new calendar day begins at the International Date Line. This imaginary line, which is located in the Pacific Ocean, is the dividing line between two consecutive calendar days. When it is midnight and a new day is starting on one side of the line, it is still the previous day on the other side.
Learn more about Calendar day beginnings