How come the sun and moon don't change in size throughout the day?

This was a question posed by my dad, who I'm in a very productive conversation with via text. I'm going to be getting up early tomorrow to catch the sun as it comes into view to confirm that I don't observe a change in size throughout the day. But in the meantime, do any of y'all have the answer to this? My initial thought was: by the time we see it, it's close enough to where the change in size as it comes overhead would be too small to notice. And that it depends on where you're at on the Earth.

Welcome eschwifty, I moved you to Q&A where you can ask questions about the flat Earth.

Be careful when observing the sun and moon. Both can be responsible for great damage to those who participate.

Both the sun and moon are far enough away, that their distance does not change appreciably throughout the day.  So, their apparent size does not change.  Pretty simple, no? 

Both the sun and moon are far enough away, that their distance does not change appreciably throughout the day.  So, their apparent size does not change.  Pretty simple, no?

FEers and round Earth believers each have their own methodologies for determining the size of sun and moon.

FEers employ facts representing the best available data for their numbers where round Earth believers use theory, deriving numbers in ways not based on factual evidence.

Advantage Flat Earth, is therefore your conclusion.