What Is Classical Astronomy?

For many people, the word "astronomy" makes them think of NASA space flights, the Hubble Space Telescope, and PBS programs about "the Big Bang." Many other people think astronomy has something to do with science fiction -- "far-out" ideas about travelling in space ships and encountering aliens from other planets. Others confuse the science of astronomy with the ancient superstition of astrology, and imagine that the legitimate study of the celestial sky has something to do with magic and divination. But all of these are largely misconceptions, and do not represent the true heritage of astronomy.

Classical Astronomy represents the traditional study of the sky as it has been done for centuries, even before the telescope. In its most simple expression, classical astronomy is simply skywatching, enjoying the celestial creation for its own natural beauty. Is there anyone who hasn't been amazed by a blazing sunset? Or seen a wondrous crescent moon hanging in a deep blue twilight? Or been astounded by the sight of bright, twinkling stars in a dark, rural sky? Such celestial sights truly prove that:

The heavens declare the glory of God, and the firmament sheweth his handiwork. -Psalm 19:1.

The Scope of Classical Astronomy

Classical astronomy is the basis for our entire system of timekeeping, and has its foundation in the Bible. We read in Genesis 1:14 that this is the very purpose for which God created the Sun, Moon and stars:

And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs and for seasons, for days and years.

The Day is the 24 hour period of light and darkness, and perhaps the most plain fact of life on Earth. The Month is based on the 29 1/2 day cycle of the phases of the Moon. The Year is the annual cycle of Sun's tilted path through the stars, resulting in longer and shorter days, and a warming and cooling in the climate. In the centuries before modern clocks and calendars, the Sun, Moon and stars were the only means for measuring the passage of time. And to the trained eye, the sky provides numerous "signs" to help observers to know their time and place under the Sun, Moon and stars.

The classical study of astronomy is intertwined with a study of geography. Astronomy is needed to understand why summer days are so long near the poles, and why the seasons are reversed between northern and southern hemispheres. Classical astronomy is also used to find longitude and latitude along the Earth. In this way, time zones and celestial navigation are understood from observing the sky.

Following this, the classical approach to astronomy is required to prove that the Earth is round. Contrary to popular thought, the Earth was proven to be round in ancient times, centuries before the life of Jesus (and millennia before NASA photographs!) Many ancient Greek writers and medieval Christian writers mentioned the sphericity of the Earth in their works. Indeed, Christopher Columbus relied on such ancient works to validate his voyage to the west in search of India. (But how many people today can cite even one classical proof that the Earth is round?)

Other aspects of classical astronomy include the causes of eclipses of the Sun and Moon, and the motions of the planets through the fixed constellations. And many of the constellations recognized today by the International Astronomical Union are based on the traditional ancient constellations. Indeed, such things were understood in classical times, and were studied by the ancient Greeks.

Classical Astronomy - An Historical Approach to Astronomy

In late classical times, astronomy was recognized as part of the Quadrivium of sciences, along with Geometry, Arithmetic and Harmony (or music). And the Quadrivium, along with the Trivium of arts -- Grammar, Dialectic and Rhetoric -- defined the Seven Liberal Arts of a classical education. Of course, most loving parents wish their children to learn geometry, arithmetic and music. But astronomy is usually not considered a priority today.

The ancient Greeks developed a mathematical system of astronomy in which geometrical methods were used to measure and describe the motions of the celestial bodies. In fact, trigonometry, the study of triangles, was originally developed for work in astronomy. The Greek philosophers Aristotle and Ptolemy established a "geocentric" astronomical system in which the Earth was understood to be at the center of a rotating cosmos.

Some may argue that, strictly speaking, "classical astronomy" refers to the "geocentric" or Earth-centered cosmology as it had been understood in the time of the Greeks and Romans. However, the ancient practices of classical astronomy remained largely unchanged following the introduction of the "heliocentric" or Sun-centered astronomy of Kopernik, Kepler, Galileo and Newton. Indeed, modern astronomers often still use geocentric illustrations, since these best describe the appearances of the starry sky.

While geometrical astronomy was developed by the pagan Greeks, classical astronomy is arguably a Christian approach to astronomy. The astronomical traditions were practiced for many centuries in Christian Europe, particularly for the purpose of maintaining the church calendar. In time, this calendrical study resulted in many advances in astronomy, leading into the modern science of astronomy.

The Almanack Tradition

One important Christian European contribution was the development of the modern almanack. An almanack typically includes tables of the Sun's rising and setting for each day of the year, along with tables of the Moon's positions, and usually the positions of planets and other noteworthy celestial objects. In this way, an almanack allows its reader to find the time during the day and also at night, which was very important before the invention of mechanical clocks.

Even though the Romans and Arabs kept astronomical tables, the European almanack tradition became very important throughout the Middle Ages. With the invention of the printing press, almanacks became inexpensive and thus widely available. The heliocentric theory became popular because it simplified the mathematics of creating an almanack. In this way, the almanacks offered classical astronomy a seamless transition between the Earth-centered and the Sun-centered cosmologies.

The almanack found its greatest expression in the early American colonies. In fact, the first English publication in America was an almanack, printed at Harvard in 1639. During the American colonial period and into the early republic, the 17th and 18th centuries, a strong almanack tradition flourished. And the American almanack also became a resource for poetry (often to the glory of God) and various useful information, in addition to the astronomical calendar pages. As we read from the early American almanacks, a knowledge of classical astronomy was common among even the simple folk at the founding of our country.

To this day, the Old Farmer's Almanac is still the best popularly-available resource for classical astronomy information. Founded in 1792, it is the oldest continuous publication in America. Ironically, the Almanac's editors lament that, while the astronomical calendar pages are the heart and soul of the Almanac, this is the least understood portion of the Almanac today. At its founding over 200 years ago, the Old Farmer's Almanac did not include any references to astrology. But sadly, elements of astrology have crept in over the years. Nowadays the Almanac includes sections on "planting by the Moon," "the Man of Signs," and other such nonsense.

Other Historical Uses for Classical Astronomy

Since 1767, a Nautical Almanack has been published in England to assist in the celestial navigation of British ships at sea. Indeed, the British used the techniques of classical astronomy set forth in the Nautical Almanack to establish a colonial empire that circled the globe. And British navigation led to the perfection of an accurate mechanical clock and a detailed understanding of the Moon's complex motions

In America, classical astronomy was used in the survey of territories and cities. Washington D.C. was surveyed with celestial observations by Andrew Ellicott and Benjamin Banneker. These celestial techniques were used in later years to survey 1.8 million acres in the North American continent. If you live in a city with roads that run east to west and north to south, your city was probably surveyed using the stars!

The Rise of Modern Astronomy

For most of history, classical astronomy was practiced with the unaided eye. The invention of the telescope only assisted and expanded the ancient tradition. By the 1800s, the modern methods of spectroscopy were developed for studying the spectra of starlight to determine the star's chemical composition. Such researches led to development of the modern fields of astrophysics and cosmology, in which broad, sweeping inferences are made of the origin and destiny of stars, galaxies and the universe, based on an analysis of starlight.

Throughout the 19th century, the center of astronomical study moved away from classical astronomy and toward cosmology and astrophysics. Nowadays, classical astronomy is of little or no interest to a majority of professional astronomers.

In the same period, mechanical clocks became popular while the sales of astronomical almanacks began to decline. The word "almanack" began to refer to any compendium of information, even those without astronomical tables. With the adoption of Standard Time around the world in 1884, timekeeping was decoupled from the Sun, Moon and stars. In the next decade, astronomy was removed from the standard curriculum in the schools. By the early 20th century, it virtually disappeared from the popular mind.

In the late 19th century, the idea of "life on Mars" became very popular. And through the writings of Jules Verne and H.G. Wells, fantasy tales of travel to other planets came into vogue. The notion of "outer space" came to fill the void left by astronomy. This notion was further reinforced when real-life space travel became a reality in the 1960s.

Today, "modern astronomy" is the rule. Popular media astronomy deals heavily with theoretical scientific conclusions of distant, unseen celestial objects. Historical, classical astronomy is widely considered a subset of contemporary "space studies." A typical astronomy book for sale at a homeschool convention mainly relates to "Big Ball Astronomy" and includes discussions  facts about the solar system, handed down on authority, with no method of practice. For example, one can expect to find entries such as, "This is Jupiter, it is a big ball of gas ten times larger than the Earth" and so on. For this reason, more people today have heard of black holes than understand why the seasons change.

Nowadays, in our high and mighty era of technology, we rely on gadgets, gizmos and other artifices of Man in the place of God's celestial order. We look at clocks and calendars to find the time of day and the day of the year. We use GPS units to tell us where we are in the world. And we never as much as glance up from our busy lives to look at the Moon and stars. Our culture has neglected and forgotten the God-given legacy of the sky.


Classical astronomy can be the perfect vehicle for teaching children the scientific method. Essentially, the starry sky offers an excellent opportunity to observe logic and order applied a natural system. The Sun, Moon, stars and planets follow predictable, mathematical motions across the celestial sky. And the changes can be observed over a period of days, weeks and months. And measurements can be made with no instruments, or just simple geometrical tools. Classical astronomy offers an interesting and practical approach to studying geometery and trigonometry (though little or no curricula are currently available.)

By studying astronomy in this manner, children can take an enjoyable approach to learning a concrete science. And they can learn a method for confirming scientific results rather than receiving such results on authority. In this way, they can learn to distinguish between observable, verifiable science and the thin, shaky evidence cited to support evolutionary studies.

A classical understanding of the sky can be learned at a local planetarium or astronomy club. Most every community has a planetarium, and these facilities are always eager for visitors. At the planetarium, you can observe the current sky, including the seasonal constellations, current positions of the planets, and perhaps the motions of the Sun and Moon. Planetariums also feature special programs and shows that highlight topics from astronomy. And most planetariums change their shows frequently, offering new programs for current events in the sky. Regular family visits the local planetarium can be a great start toward developing a classical appreciation of the sky.

Many astronomy clubs work in conjunction with local planetariums. Astronomy clubs are made up of enthusiastic amateur astronomers who love to help astro-novices learn their way around the night sky. Amateur astronomy clubs have public nights in which the members set up telescopes for the community. On any given public night, splendid telescopic views of galaxies, nebulae and the planets can be expected (weather permitting!) And every club has at least a couple veteran amateur astronomers who know everything about the sky and would love to point out constellations and answer questions for interested learners.

A list of planetariums, amateur astronomy clubs, and observatories can be found at the Sky & Telescope web site. But even after doing all this, there's no substitute for personal experience! So get out and look for yourself!

Excellent recommendations were given in 1900 by Asaph Hall, the famed discoverer of the moons of Mars:

To begin with the elementary Astronomy, it seems to me that it should be taught in the high schools and preparatory schools, as well as in the colleges. Preparatory work in it ought to be accepted for admission to college. By elementary Astronomy I mean those common, every-day facts of the science which can be learned by any intelligent student without mathematical training; for example, why the stars rise and set, the motions of the planets and the moon among the stars, the reasons for the seasons, the names of the principal constellations and why they seem to change with the seasons. These are things that are before our eyes all the time, and every one who is fairly well educated ought to know something about them.

Over a century later, the schools have yet to take Professor Hall's recommendation. This represents a golden opportunity for Christian homeschoolers, who respect God's creation and seek to rediscover the lost traditions of a bygone era. And the Classical Astronomy web site is dedicated to helping the next generation rediscover our lost astronomical traditions.

Jay Ryan is the author of Signs & Seasons, an illustrated, Biblically-centered homeschool curriculum for Classical Astronomy. He is also the creator of the Classical Astronomy Update, an email astronomy newseltter especially for Christian homeschoolers.  Visit his website at ClassicalAstronomy.com.

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