Introduction
Tools to Answer Cosmic Questions

Astronomical observation has its roots in antiquity. Ever since the citizens of ancient Babylonia, China, Egypt, and Greece designed crude wood tools to measure the movement of the stars and planets across the heavens, humankind has been improving those primitive implements to investigate the cosmos and attempt to understand its workings.

Those early astronomical tools, like all tools, were extensions of people's interest to know more—in this case to know more about Earth's celestial movement and the moon's rotation around Earth, and to understand the mechanics of the solar system. Using tools called quadrants and astrolabes, early astronomers answered questions about the regular movement of planets and the distance from Earth to the moon and sun. These devices also aided explorers such as Christopher Columbus and Ferdinand Magellan by determining the earthly position of their ships across the uncharted seas.

As astronomy gradually developed into a science that observes and describes the universe, better astronomical tools replaced older ones. Missing from the astronomer's tool chest for thousands of years, however, was some sort of device capable of improving astronomers' ability to see the stars and planets—one that would allow them to investigate with greater

precision the great expanse of the universe and to understand its clocklike movements.

When that missing tool, the telescope, finally emerged just four hundred years ago, astronomy shifted gears from an archaic pseudoscience dependent on unaided eyes to understand the universe to a modern technological science reliant on the latest high-tech advances. In the early years of modern astronomy, telescopes answered increasingly complex questions about Earth's rotation around the sun, the size of the solar system and its number of planets, and how many stars are in Earth's galaxy, the Milky Way.

It is not surprising that today, with hundreds of telescopes scattered across the earth and dozens more orbiting in space, they remain the grandest of astronomical tools and the most formidable extension of people's quest to raise questions never imagined by earlier civilizations: How old is the universe, how did it begin, how big is it, and will it last forever?

As long as questions about the cosmos remain unanswered, scientists will improve their telescopes to try and answer them. As astronomer Robert Lin at the University of California's Berkeley campus reminds people, "Astronomy is not a hands-on science. We can't go into deep space to study stars and galaxies; we must rely on our tools." ¹ For this reason, twenty-first-century astronomers continue to astound the public by inventing increasingly exotic telescopes, assisted by computer technology, that peer ever deeper into the mysteries of the universe.