The Sun’s apparent size at different times of the day is a matter of comparison.
At sunset the sun is usually positioned near Earth’s horizon instead of directly up in the sky. The mind unconsciously compares its size to the size of the objects nearby.
Next to trees, houses, roads, or buildings, it looks huge. Next to blue sky and clouds, it looks smaller. Believe it or not, the sun is actually over 3,700 miles closer to Earth at noon than it is when it’s setting.
When compared to the total distance that separates Earth from the sun, however, 3,700 miles just isn’t that big of a deal.