How did Ptolemy use eccentric circles to explain the Sun’s changing speed in the zodiac?

In the Ptolemaic system, Ptolemy utilized the principle of eccentric motion to account for the Sun’s varying speed as it moves through the zodiac.

While ancient astronomers held that celestial bodies must travel in uniform circular motion, observations from a stationary Earth showed that the Sun’s speed appeared to change throughout the year. Ptolemy explained this by postulating that the Sun travels at a constant speed along a circular path whose center is slightly displaced—or "eccentric"—from Earth.

Because the center of this path is not Earth itself, the Sun sweeps out equal angles in unequal times from a terrestrial perspective. Consequently, the Sun appears to move fastest when it is at its closest point to Earth (perigee) and slowest when it is at its farthest point (apogee). This model allowed Ptolemy to reconcile the requirement for uniform circular motion with the observed irregularities in the Sun's transit across the sky.12