* The sky isn't a physical thing: The sky is just what we see when we look up at the atmosphere. The atmosphere extends hundreds of kilometers above the Earth, but it doesn't have a defined edge.
* It depends on your perspective: From our point of view on Earth, the sky seems like a dome or a vast canvas. But if you were in space, you wouldn't see a sky at all!
* The universe is HUGE: Even the atmosphere is small compared to the universe. The universe has no edges, and it's constantly expanding.
So, it's impossible to say how big the sky is in a specific way. It's a vast, ever-changing concept that depends on how you look at it.
