Refraction in the air squashes the Sun near sunset. Atmospheric refraction makes everything seem slightly higher in the sky than it actually is. Because the thickness of the Earth's atmosphere increases toward the horizon, the Sun is more-lofted upward at its lower edge than at its upper edge, which flattens it. The increased thickness also makes the lower edge of the Sun dimmer and redder than the upper edge. A large sunspot can be seen toward lower left. (Note: Do not attempt to view this effect without proper equipment, as the Sun is usually too bright to look at.)