The study of the stars, planets, and phenomena outside the atmosphere of Earth is all lumped together into a science called astronomy. Most people think that the study of the heavens is an easy-going, relaxing look at little pin-points in the sky. Those people are far wrong. The most powerful and awesome forces in the universe are the subject of astronomy, from fearsome novas to black holes that are so strong they even suck in light. There are gas giants, nebulas, and vacuums were no molecules at all exist.


Astronomy is one of the oldest of the sciences. People have been studying the skies and recording their observations since the dawn of history (about 3500 B.C.). At one time astronomy was confounded with astrology and religion. Many ancients believed that astral bodies were actual gods or that they had a powerful daily influence on the behavior of humans. This seemed a reasonable belief when primitive peoples could plainly see the effects of the sun, creating night and day, and influencing the weather. The moon affected tides and could be related to menstrual cycles of women. It was logical to attribute great power to the stars.

Nevertheless, like the other sciences, Astronomy became subject to the scientific method. When the telescope was invented in the early 1600s people began to get a closer look at the planets and the stars. Galileo was the first to get a close look at the planet Jupiter and let the world know that the greatest of the planets in our solar system had many moons.

From ancient through Medieval times seamen were afraid to sail or row out of the sight of land. However, once they understood that the sun, moon, and stars could be used to navigate, celestial navigation gave a huge impetus to the study of astronomy. While east from west could be determined by the rising and setting of the sun, and north from south could be determined from the position of the north star, a great advance occurred when it was realized that latitude could be determined by the angle of the sun from the horizon. Since the angle changed every day, meticulously compiled tables were created to help navigators place their location on a map. It was not until accurate time keeping in rough conditions was invented in the form of the chronometer that latitude could be determined at sea.

With telescopes allowing people to see farther and farther into space and the discovery of laws governing gravity and physics old assumptions about astronomy began to fall away. Copernicus revealed that the Earth was not the center of the universe. The longtime connection between astronomy and astrology disappeared. Celestial navigation became a field of its own and astronomy became more a study of physical phenomena in space. In fact astronomy is often referred to today as astrophysics.

Today astronomy delves into planetary phenomena that goes far deeper than merely understanding the motion of particular planets. Many tools such as radio telescopes and listening devices are employed to gather data from the far ends of the known universe. This knowledge is vital should humans ever understand the beginnings of our cosmos and reach out to discover, explore, and settle our moon, our solar system, and our galaxy.

Next Page: Why the Moon Waxes and Wanes

Interesting Fact:

Astronomers use highly sensitive instruments to look out to "look back in time" to try to determine the origins of the universe.

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