* We haven't mapped every star: Astronomers have only been able to observe and catalog a fraction of the stars in our galaxy.
* Stars are constantly forming: New stars are constantly being born in nebulae within the Milky Way.
* The galaxy is vast: The Milky Way is a massive spiral galaxy, estimated to contain hundreds of billions of stars.
However, estimates suggest that there are likely trillions of star systems in the Milky Way.
Keep in mind that a "star system" can include a single star with planets orbiting it, multiple stars orbiting each other (binary or multiple star systems), or even a central star with surrounding nebulae or other objects.
