Answer:it is because of a timezones
Explanation: where it may be daytime in japan i would be night in New York.
For example, if you are in New York and your friend is in japan and you guys called each other you would see that it is day for you and night for them.
the cause of timezones is places bieng on the oposite side of the world. If the sun is shining on one side of the world then it is day and if the sun is not shining on the other side of the world then it is night.
HOPE THIS HELPS!!