Anyone visiting their local bookstore or public library sees hundreds of books on astronomy. Topics range the full gamut; from asteroids colliding with Earth (e.g., extinction of the dinosaurs) to the possibilities of life on other worlds (e.g., exobiology or the Search for Extra-Terrestrial Intelligence; a.k.a. SETI). There are yearly almanacs with tables listing positions of the sun, moon, and planets as well as pictorial table top books showing how the planets and galaxies look through the cameras of deep space probes or the Hubble Telescope. If you need to know how to build a telescope or photograph galaxies, the sources are just a short walk or drive away. It won't be too long when all this information becomes accessible to anyone on their personal computer through the World Wide Web; for example in just seconds.

This book (more like a handbook) is intended to provide a general appreciation for the rarity of planetary, lunar, and solar configurations in the sky. Unlike many books on astronomy, I have attempted to show the rhythm of the planets and their moons and have provided excellent references in each footnote for those seeking more details. The bibliography also suggest additional reading sources for those interested. There are undoubtedly more examples of interesting and unusual celestial alignments which I encourage you to explore with today's astronomy software. The bottom line is that if you are not motivated to take your telescope or binoculars outside one very cold winter's night, maybe you will if you realize that you won't have a second chance to observe a once-in-a-lifetime Predictable Astronomical Event.


On 20 July 1994, at exactly 25 years to the minute when man first stepped foot on the Moon, a bolt of lightning struck a tree in front of my house while I stood only 30 feet away. At the same time, halfway across the solar system, Comet Shoemaker-Levy 9 was cascading into Jupiter with cataclysmic effects the likes never witnessed before. The coincidences and significance of these milestone events actually have something very much in common. They both belong to a class of phenomena which is not predictable over any useful time frame or dimensional scales. Perhaps chaos and quantum physics may never allow us to control our ultimate environment, however fortunately, at an everyday level of human interaction, we do a pretty good job at predicting most outcomes. Consequently, I was lucky to have survived this chance encounter. The tree's unplanned meeting with several million volts faired as well and Jupiter's gaseous atmospheric belts repaired themselves in the following months.

As an amateur astronomer, I have often wondered why things in nature are beautiful. Philosophers over the millennia have attempted to definite aesthetics but I believe have missed articulating what the essence of this subjective perception of reality is. We appreciate the value of an emerald because of its color, durability and rarity. The question then is whether beauty has to be something tangible or materially valuable.. I believe that beauty holds something much deeper. The importance in our ability to explain and therefore predict an outcome of something we are observing is what makes it beautiful. We take comfort in the familiarity. Beauty then becomes more than just what the eye of the beholder sees. Beauty is one's ability to make sense from all the unpredictable noise we call randomness.

On 8 April 1977, I viewed Mars' occultation of the bright star Mebsuta (2.9 magnitude) in the constellation Gemini. This event was heralded as not only a once-in-a-lifetime occurrence, but one of just a few of this type visible in a millennium. Was this really true and if so why. There are thousands of stars visible to the unaided eye, so surely a planet must occult one frequently. What then is the dynamic relationship each body in the Solar System has with one another and the nearly stationary background stars? Perhaps because statistics associated with celestial mechanics is always changing as the planets' gravity and tidal forces interact in extremely complex ways, the task of documenting orbital commersurability and sygyzy is a useless endeavor. I believe with some patience, one can acquire an appreciation for these inter-dependencies.

The 32 bit personal computer has truly opened the world to endless possibilities. We now have the capability to predict the time, location, and physical aspects of nearly anything we can imagine. As amateur astronomers, we now have a virtual reality time machine that can take us to the far reaches of our solar system at an instant and at an epoch. It is with this in mind that I have attempted to compile a periodical time dependent sequential list and non-periodical list of most commonly known astronomical phenomena that are predictable and observable (without elaborate equipment) from Earth. Many events will require traveling to foreign locales such as witnessing a total solar eclipse. Other's will occur several times over a brief time span but will not return for centuries such as a triple conjunction of Uranus and Neptune. In complying these data, I applied a certain amount of discretion. As with any statistical undertaking, data that marginally fits a specific criterion is open to interpretation and acceptance. For example, just how far in solar elongation can planets be seen when occulted by a very young or old Moon? This depends on the inclination of the ecliptic plane to the horizon. I have made every effort to provide caveats in defining particular events.

A final point. In developing this book, I became convinced that the movement of heavenly bodies in our solar system is very much like a graceful ballet. Events occur with precision for us to marvel and admire. There will always be the purist who will argue that the data presented are off at the third decimal place or an hour of time for an event in the year 500 A.D.. They might be correct with their assertion if they truly know the non-linear rate that the Earth's rotation is decelerating. I doubt anyone knows for certain since the historical record of astronomical events gets more clouded in the distant past. So the intent of this book is to help the casual observe appreciate the uniqueness of what they experience every time they use a telescope or naked-eye. Experienced amateur astronomer should find this source book as a useful companion to other almanacs. At no time does this book attempt to advance beyond a basic introductory level of astronomy. Its purpose is to invoke curiosity. Perhaps you can discover other interesting predictable astronomical events. Good hunting!

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