1. The Big Lens (Objective)
Acts like a giant "light bucket". It catches parallel light from a distant star and squeezes it into a single bright dot (the focal point).
2. The Crossing
The light rays cross over each other! This means the image of the star is actually upside down inside the tube.
3. The Small Lens (Eyepiece)
Acts like a magnifying glass for your eye. It straightens the rays back out so your eye can see a giant, zoomed-in picture!