A lineup of the crescent moon and top of the Transamerica Pyramid.

I’ll never forget Fred Larson’s iconic “Moon Over Coit Tower” photo, a stunning example of the celestial lineup - the moon backing an earthbound object, such as a skyscraper or bridge.   The moment I first saw it, I vowed that someday, somehow, I’d learn how to “do that myself.”   Unbeknownst to me, with those few, fateful words, I’d taken a gigantic figurative bite. So big, in fact, as to be almost unchewable.  I damn near had to Heimlich myself!

You see, as the earth spins on its axis, the moon steadily pans across the sky, moving its own width every two minutes.  This motion escapes the naked eye, and is completely irrelevant to most types of photography.

But the lineup is different.  To capture a “big moon” requires a correspondingly big, honking lens.  At these necessarily extreme focal lengths, with their narrow field-of-view, the moon moves fast. So quickly, in fact, that you can actually see it slide across the viewfinder screen!  For example, using a 600mm lens on a Canon 50D, the moon travels across the sensor at nine pixels per second!

The moon’s motion ensures that a lineup is fleeting - that it’ll last a few minutes as viewed from any one spot, tops. And there’s other complications. You’ve got a handful of landmarks to place in front of your moon, and a limited number of vantage points to shoot them from.  You’ll want capture the moon near the horizon so as to attenuate its brightness, and consider the ambient light, such as from a waning sunset.

Add it all up, and you begin realize that Luna heartily chuckles at unprepared slackers!  A particularly elusive lineup might only be visible twice a year, from a small patch of earth, at a specific hour, for a few precious seconds.  To maximize your chances of capturing it, you’ll need to be in the right place at the right time, fifteen minutes beforehand, since you’ll have to lug a tripod and camera into the field and set them up first. 

But how to know where and when to go, in advance?   Quite simply, you’ve gotta suss it all out by yourself.  A few days prior to each full moon, I’d do just that - old school, by poring over charts and tables and maps and estimating the time and place of the best shots by judicious application of mental brute force.

Hey, aren’t computers supposed to be good at that kind of thing?

Why, yes, indeed.  In a few days, I’d whipped up a C++ program that automated all those pesky calculations.  In went a database of landmarks, vantage points, and a time range, and out came a list of the interesting lineups, formatted like this:

"Bay Bridge, Second Tower, Top" from "Embarcadero, Club Promenade"
    moon within 0.1 degrees at Thu 01/Feb/2007 17:48:19 PST
    to landmark: alt 5.8 deg, az 69.3 deg, distance 1.55 km
    to body: alt 5.8 deg, az 69.2 deg
    from lat,lon 37.795888,-122.391322
    sun at -3.7 degrees
    phase 100%

Upon traveling out to the most promising spot, at the designated time, reality and the predictions matched exactly.  Eureka!

Lately, alas, the lineups have taken a backseat to other pursuits.  But my computer program still wants to feel useful!

So, from time to time, I’ll be posting the specifics of an upcoming San Francisco Bay Area lineup: where to go, when, and what you’ll probably see.  Feel free to use the information however you please, within the terms of the Lineup License under which it’s available!  Shoot the lineup.  Watch other people do so.  Or simply go out there to witness a beautiful display of the predictability of our universe.

Enjoy!