No one science can stand wholly on its own. For inquiry about the Universe to give a correct, complete picture, it requires that we bring in a whole slew of evidence, often from tangentially related fields.
The interplay between three fields in particular — astronomy, physics, and math (not a science, but the tool used to help understand the relationships arising in the first two) — have given rise to the most successful picture of the Universe of all-time.
But how did this come to be?
Brian Koberlein has the story on the difference between what makes a robust science and a mere numbers game.