It is interesting because the sky can be so many different things to us: it can be big, beautiful and blue, or gray, with clouds and rain. It can also be full of stars, or it can be filled with orange and red clouds at sunset or sunrise.
The reason the sky looks like so many different things is because what we see in the sky is actually just a different behavior of the large gas membrane over our heads. That layer, which we call the atmosphere, is attached to our planet, Earth, by an invisible force called gravity, and we are subject to it. And depending on the time of day and the atmosphere, we will see things differently.
As an astrophysicist student, I am particularly interested in the sky, because it is my job to learn about the various things we find there. I remember the first time I looked at Saturn through a telescope. Usually, when you see Saturn in the sky with your own eyes, it looks like a bright star - but when you look at it through a telescope, it suddenly becomes global! It just bothered me that it was just hanging there in such a large space.