Pinpoint Stars

Galileo saw that the Milky Way, which appears as a dusty band across the night sky, actually consists of thousands of stars.

Surprsingly, the stars near the milky way appear smaller when viewed through the telescope than with the naked eye.

Unlike the planets in our solar system, the stars are so far away that they are only points of light. It is the optics of the eye which diffracts the starlight and spreads it out.

Galileo had no explanation for this, except to note that the stars must be very, very far away compared to the planets.