Understanding the Basics

* Earth's Rotation: The Earth rotates 360 degrees in 24 hours, meaning it moves 15 degrees per hour (360/24 = 15).

* Longitude and Time: Every 15 degrees of longitude corresponds to a one-hour difference in solar time.

* Standard Time Zones: We use standard time zones to simplify timekeeping, but solar time varies depending on your longitude.

Calculation

1. Longitude Difference: The difference in longitude between 72°W and 90°W is 18 degrees (90 - 72 = 18).

2. Time Difference: Since every 15 degrees corresponds to one hour, an 18-degree difference equates to 1.2 hours (18/15 = 1.2).

3. Solar Time at 72°W: Since it's noon at 90°W, and 72°W is 1.2 hours ahead (because it's further west), the solar time at 72°W would be 12:00 PM + 1.2 hours = 1:12 PM.

Therefore, the solar time at 72 degrees West longitude would be 1:12 PM if it is noon at 90 degrees West longitude.