Final answer:
The average time between appearances of the Sun on the meridian is 24 hours, known as the mean solar day. It's slightly different from a sidereal day, which is about 23 hours and 56 minutes. Mean solar time accounts for the Earth's rotation and the additional time needed to align with the Sun after a complete rotation relative to the stars.
Step-by-step explanation:
The average time between appearances of the Sun on the meridian is based on the concept of mean solar time. This time frame corresponds to a mean solar day, which contains exactly 24 hours, the time period most of us are familiar with for everyday activities.
This is different from a sidereal day, which is approximately 23 hours and 56 minutes, the time it takes for the stars to make a complete circle in the sky.
The difference occurs because the Earth must complete just over one rotation relative to the stars to align with the Sun again, resulting in approximately 4 minutes added each day. These 4 minutes add up to provide a clear distinction between sidereal and mean solar time, the latter of which is uniform and convenient for everyday use.
When considering the progression of solar time, we should also take into account the apparent path of the Sun, known as the ecliptic, which causes the Sun to rise about 4 minutes later each day with respect to the stars. Furthermore, the concept of noon in mean solar time corresponds to the time when the Sun is highest in the sky on the meridian. However, because of Earth's round shape, this exact time differs based on longitude position.