Final answer:
The Sun's apparent daily motion is caused by Earth's axial rotation, with the Earth needing to rotate slightly more than 360 degrees for the Sun to appear in the same position in the sky the next day. Variations such as the 'equation of time' and the Sun's movement on the ecliptic also affect its apparent position.
Step-by-step explanation:
The apparent daily motion of the Sun is explained by the rotation of the Earth on its axis. As the Earth rotates, it gives the illusion that the Sun is moving across the sky when in reality, it is the Earth's movement that causes this phenomenon. With each rotation, the Earth must turn slightly more than a full revolution to align with the Sun again, which is why we experience a roughly 4-minute difference each day compared to the stars. This is part of what's known as the solar day.
Furthermore, due to the Earth's elliptical orbit and the tilt of its axis, we experience the 'equation of time' and see a variation in the Sun's position throughout the year. The ecliptic path is the apparent annual journey of the Sun against the backdrop of the celestial sphere, which also contributes to the changing position of the Sun as seen from Earth.