Guest Author - Lea Terry

Long before we had clocks, long before we had compasses, we had astronomy. It is the oldest physical science, dating back to prehistoric times, when early humans gazed up at the sky with wonder, awe and many times, fear. It is also how humans navigated their way through a largely unknown terrain, and how they understood their place in the world. This ancient form of astronomy was called positional astronomy. It is the oldest branch of the science.

Because early humans couldn’t analyze a star’s composition or study a planet’s atmosphere, their astronomy was limited to documenting the positions of celestial bodies. Those early astronomers didn’t have access to the high-powered telescopes and sophisticated technology of modern scientists. And they certainly couldn’t travel to another planet and bring back photos and soil samples. They had to depend on their own eyes. Early astronomers learned a lot by watching the skies, but they had to assume even more. With only a small amount of data, they had to rely on speculation to fill in the gaps. This led to farfetched, complicated models, such as Greek astronomer Ptolemy’s theory that Earth was the center of the universe. This, he believed, explained why the Sun and planets appear to move across the sky.

While this astronomy was primitive by today’s standards, it was an important part of daily life for early humans. Religious festivals and ceremonies were often timed in accordance with the positions of heavenly bodies. It was also the only form of navigation. In the northern hemisphere, for example, you can find your way simply by locating the star Polaris, which sits above the North Pole. In its earliest form, astronomy was indistinguishable from astrology. One of the primary reasons for documenting the positions of heavenly bodies, in fact, was for the creation of star charts and horoscopes. Early civilizations believed you could predict personal and world events by studying the positions of the stars and planets.

Modern astronomy is more advanced and accurate than early efforts, but positional astronomy is and was a valuable tool. While it produced often outrageous theories, it was the first scientific, methodical attempt to understand our universe. And the information it yielded formed the basis for all astronomical observation that followed.