Why does the moon seem to get bigger and smaller?

The moon appears to change size due to its phases and the optical illusion known as the "moon illusion." As the moon orbits the Earth, different portions of its surface are illuminated by the sun, creating phases from new moon to full moon. Additionally, when the moon is near the horizon, it often looks larger compared to when it is high in the sky, due to its context against terrestrial objects and atmospheric perspective. However, its actual size remains constant; it's our perception that varies.