Equation of time zero dates: On which dates do the true (apparent) Sun and the mean Sun cross the same local meridian at the same instant (i.e., the equation of time is effectively zero)?

Introduction / Context:
The apparent Sun does not keep uniform time because Earth’s orbit is elliptical and its axis is tilted. The “equation of time” quantifies the difference between apparent solar time and mean solar time. On certain dates, this difference becomes zero.

Given Data / Assumptions:

• Standard civil time uses the mean Sun (uniform rate).
• Apparent solar time follows the true Sun’s meridian passage.
• Approximate zero crossings occur on four dates each year.

Concept / Approach:
The equation of time varies roughly between about −14 minutes and +16 minutes during the year with four zero crossings. Typical near-zero dates are mid-April, mid-June, early September, and late December. Hence on or about April 15, June 14, September 1, and December 25, the true Sun and mean Sun transit the meridian together.

Step-by-Step Solution:
Identify the listed dates as standard zero-crossing approximations.Conclude that each date is acceptable for “same meridian at same time.”

Verification / Alternative check:
Annual equation-of-time graphs show the four crossings; exact dates vary slightly by year, but the listed dates are conventional approximations used in surveying texts.

Why Other Options Are Wrong:
Choosing only one date ignores the other valid crossings; “All of the above” is the comprehensive correct response.

Common Pitfalls:
Assuming the dates are constant to the day every year; small shifts occur due to leap years and orbital perturbations.

Final Answer:
All of the above.