A shame, @steevc because although that I think you're technically correct, I believe you're doing a very troublesome job proving it.

The dark truth is that most people are in cults. Christianity, Islam, Hinduism, Judaism, or perhaps even communism, nazism, democracy, republicanism, or liberalism. Or science.

Of course it's not that the written method of science is a cult necessarily. It's that your MIND; your brain, CRAVES cults to join. Cults, groups, cliques, a people, a nation, a team, a tribe. Or an answer that puts to rest your fears, uncertainties, and doubts.

Thus you have allied yourself with at least the general direction of science, such that you would scoff at @kencode's potential belief that relates to a firmament or mythological existence, but although I will expect @kencode to find it very hard to actually PROVE a firmament exists and especially come up with ways to utilize it, or even land on the firmament, and mine it for resources, I'm finding it amusing how you are also failing to prove your point.

Do you actually understand what you believe?

I was very specific in how I presented my evidence, when detailing the size-distance ratio, and how 5 degrees of sky really does seem like a reasonable answer. My math has yielded an element of truth.

Of course the answer can't be presented in inches or millimeters, but 5 degrees of a sky arc is the answer, and that's just about how it looks whenever I see the full circle of the sun in real life.

But I'll anticipate circle vs sphere and answer that: How do we know it's a sphere? We'd watch as it rotates, or as we orbit around it. Just track the features, such as sunspots, and immediately we have a very clear way to know the shape of the sun, even if the size is unknown.

However, @kencode is right that we could use two lasers in different locations to measure the distance of the sun. What we would do is be exactly one or two kilometers away from each other, and simply shine the lasers at the sun and observe when they hit the same spot on the sun. Then we shine the same laser at each other, completing a full triangle. From there, we can begin to see how we would form an equation to solve the length of the sides of a triangle.

The more data we gather, such as the shape, the distance, the size, the trigonometry details, the composition, and how it works, such as elemental or chemical makeup, nuclear science, star fusion details, etc, the closer we can triangulate the true nature of our star.

But this is a real example that you can actually implement, and understand why it works. @Steevc, you need to have a little more respect for @kencode. Do you realize the sort of society we live in? It is NOT easy to trust people, especially mainstream things, such as politics, religion, culture, corporations, and science. There is no reason why "trust" should extend beyond my family, friends, and neighbors. These other people are strangers. The politicians, the CEOs, scientists, and all others with power or influence in society. They're strangers whom I have never met. There is no strong reason to trust either schools or Google or anyone else that I don't personally know.

And even if they intrude into my life, that still does not mean I would trust them. But I can at least utilize math and logic and natural facts that I myself can test, and do test.

Only lies and falsities come up with random fake answers or excuses, or explanations that completely fail to convince. Fake answers will be inconsistent, and not fit into anything else we know. For example, one reason why a firmament is illogical is because when we look at other planets in space, we are able to watch the moons of those planets orbit around those planets, and watch those planets orbit around the sun.

The intense 3D nature of orbits, including on the atomic and sub-atomic level, where we never deal with anything like firmaments, but instead, we always deal with spheres, or "droplets in zero-gravity" with other spheres orbiting them, drives away the idea of a firmament very effectively. Firmaments just aren't seen anywhere in real life, so I am not convinced that I will ever see a firmament. I've used telescopes before. I've seen the real details regarding stars and planets and even distant galaxies. A firmament is just not a realistic answer.

The closest thing to a flat firmament in space is our galaxy, which orbits in a very flattened shape, like a nicely fried egg. Is THAT the true meaning of firmament? Our galaxy? If that was the true ancient meaning of the word firmament, as if to imply that our galaxy is a unit that we can someday explore, although other galaxies are likely too far away, then that would be an answer that is both consistent and logical, and doesn't call into play supernatural entities, nor does it bring up concepts too technical or complex for us to explain and talk about together.

I prefer to keep things as simple as necessary, because if I ever find that I cannot explain something that I believe, I immediately darkly ponder just why it is that "truth" should be so hard to explain.