Galileo was the first to discover the moons of Jupiter. Michael Benson / Kinetikon Pictures / Corbis (Jupiter) / Scala / Art Resource, NY (Galileo) Inside a glass case was a plain-looking tube ...

Well, any of us who has ever looked through a telescope could say the same, for the two principal types in use today were developed by giants: the refractor by Galileo and the reflector by Newton.