If you’re reading this, I hope you feel the same sense of luck as an astronomy enthusiast that I feel to be alive right now. In less than three months, you and I will have the chance to view one of the rarest of all predictable celestial events — the transit of Venus across the face of our star June 5/6, depending on where you live.
Because of the geometry governing the orbital planes of our planet and our “sister planet” around the Sun, such events only happen twice every eight years — each pair separated by alternating periods of 105.5 and 121.5 years! In other words, every non-Cylon who witnessed the last Venus transit across the Sun in 1874 and/or 1882 is now dead.
Transit: When Planets Cross the Sun, written by Michael Maunder and Sir Patrick Moore (Patrick Moore’s Practical Astronomy Series, Springer, 1999). Chris Raymond photo
Hopefully you’re among those who glimpsed the small black dot of Venus slowly track across the massive blazing surface of our star in 2004. But if you’re like me and didn’t get that opportunity, then you definitely need to make a point of witnessing this one — literally our last chance because the next pair won’t start until December 2117.
To that end, I’ve been reading everything I can get my hands on for several months in order to better understand what will happen and, more important, how I can see it. The June 2012 issue of
Astronomy magazine contains several excellent articles about the transit — particularly one by Senior Editor Rich Talcott — so don’t miss that issue when it hits newsstands May 1. But I want to share what I’ve found useful in the interim.
The first book I read was
Transit: When Planets Cross the Sun, written by Michael Maunder and Sir Patrick Moore (Patrick Moore’s Practical Astronomy Series, Springer, 1999). While published five years before the latest Venus transit (2004, and unbelievably not updated and reissued yet by Springer in anticipation of the June 2012 transit), I still enjoyed and found great value in this work. Yes, some of the text feels rather dated now — particularly the sections on “Cameras” and “Film” in chapter 17, “Photographing Transits” — but, overall, I found this book of immense value as I prepare to witness this last-in-my-lifetime event.
What first drew me to this book following my Google search was the historical information it contains. Chapters 5–9 offer details about the Venus transits of 1639 through 1882. I enjoyed the broad perspective these chapters provided — especially concerning the transits of 1761/1769, which represented the first worldwide effort to glean scientific knowledge from a coordinated transit-viewing effort because of the previous predictions of famed astronomer Edmond Halley. In fact, nearly 200 astronomers from more than 120 sites around the planet pointed scopes at the 1761 transit and carefully recorded their observations. Foremost, this initiative hoped to better determine the astronomical unit, the distance between Earth and the Sun.
But aside from the history, the initial chapters in this 164-page book provide readers with a basic understanding of transit geometry — the critical alignment of Mercury or Venus between Earth and the Sun. While an additional graphic or two detailing the orbital paths of the inner planets would have been nice, the text clearly explains what needs to happen for earthlings to see a tiny planetary silhouette slowly cross the surface of our star. Incidentally, transits of Mercury occur far more often than those of our sister planet — generally at least once a decade. The next one will occur May 9, 2016.
The latter chapters in “Part 2: Observing Transits” offer a great primer on how you and I can see this rare event June 5/6, and even photograph it for posterity if we choose. After the necessary safety overview — and here I remind you to
never look directly at the Sun with naked eyes — the authors detail which types of telescopes are best suited for viewing this event, the various types of filters that can be used, and how to use a scope to project the Sun’s image onto a white screen. (That’s what I plan to do using my little 70mm Celestron.)
The last two chapters explore how to photograph transits using film, digital, video, and CCD cameras, and then how to enhance the captured data. As noted earlier, these two chapters feel the most dated. As the “Digital Cameras” section itself states, “Digital camera technology is advancing rapidly.” Even in hindsight, it’s difficult to fault those writing some 13 years ago for failing to anticipate how rapidly and completely digital has supplanted film. Just ask Kodak.
Regardless,
Transit: When Planets Cross the Sun both enhanced my understanding of such events and elevated my enthusiasm in anticipation of June’s event. I can’t wait!