Question

at which longitude does the date change

Answer 1

The International Date Line around the antemeridian takes 180 degree longitude taken as an imaginary line of demarcation.

It lies on the surface of earth and runs from the North Pole and to the South Pole for demarcate the changes of one calendar day to the next.

This happens every day and date changes by means of International Date Line as an imaginary line of demarcation on the surface of earth.

Answer 2

"The date changes on the "meridian of 180° longitude". It is an "imaginary line" which is also known as the "International Date Line" (IDL) on the surface of the earth and runs from the "North Pole and to the South Pole". This line simply defines the relationship between the date line and time in a day.

The International Date Line (IDL) crosses between the Aleutian Islands of United States and the "Commander Islands", which "belong to Russia"."