How much time difference exists at the 180 degrees meridian compared to the prime meridian?

The 180 degrees meridian, also known as the International Date Line, is 12 hours ahead or behind the prime meridian, which is located at 0 degrees longitude. This time difference arises because the Earth is divided into 24 time zones, each representing 15 degrees of longitude. As you move east or west from the prime meridian, the time changes by one hour for every 15 degrees.

Since the Earth is a sphere, when traveling from the prime meridian to the 180 degrees meridian, you've traversed half of the globe. Consequently, this results in a time difference of 12 hours. This is why the correct answer indicates a 12-hour difference; at the 180 degrees meridian, you effectively experience the opposite time of the prime meridian.