What's Inside a Baseball?
Before baseballs became regulated, they varied from game to game. "Lively" balls had a solid rubber core and were bouncier. "Dead" balls were heavier and didn't fly as far. Home teams chose which ball to use during the game, and would select a ball that played to their strengths—a lively one if they had strong batters, a dead one if they were better in the outfield. Today, a single baseball may take a week to make, but in a Major League game, its lifespan is typically just a few pitches.
from Science Channel
Key Facts In This Video
The core of a baseball is called "the pill," and consists of a sphere of cork inside rubber casing. (0:09)
Layers of yarn inside a baseball allow it to retain its shape after being hit. (1:06)
It takes one week to make a professional baseball. (2:44)