12 hours
Explanation
The calculation of time differences across the globe is based on the Earth's rotation. The Earth completes one full rotation (360°) on its axis in approximately 24 hours. This relationship establishes the basis for time zones relative to longitude.Detailed Analysis:
- The Prime Meridian is designated as 0° longitude.
- The International Date Line is located approximately at 180° longitude (diametrically opposite to the Prime Meridian).
- The longitudinal distance between them is exactly 180°.
- Calculation: Since the Earth rotates 360° in 24 hours, it rotates 15° in 1 hour ($360/24 = 15$).
- Therefore, to cover a difference of 180°, the time difference is:
$180^{\circ} \div 15^{\circ}/\text{hour} = 12 \text{ hours}$.
Key Takeaway: The Prime Meridian (0°) and the International Date Line (180°) are separated by 12 hours, which constitutes exactly half of a solar day.