Following Moon Shadows

by Alan Dyer

I’m off chasing moon shadows again. Even die-hard amateur astronomers ask me, “Why go to another eclipse?” Only those who have never seen a total eclipse of the Sun ask that!

Then I’m asked: “Sure, I can understand going to one eclipse, but aren’t they all the same?” My answer is that even if the Sun did look the same at every eclipse (it doesn’t), going to each eclipse would still be worth it because the difference, as the real estate agents say, is all in the location, location, location.


Last year, in August, I was in the Canadian Arctic. For the eclipse before that, in 2006, I was in the Libyan Desert. This year, I’m writing from the South Pacific, where we hope to view the July 21 eclipse at sea in the Northern Cook Islands from the MS Paul Gauguin cruise ship. You couldn’t ask for three locations—and eclipses—that are more different.

From Libya, the Sun was high in a noonday sky. From Nunavut, the Sun had just risen. From the Cook Islands, the Sun is about to set. Each of those circumstances produces a unique experience. What people who have never seen an eclipse don’t realize is that it is not just the sight of the eclipsed Sun itself that is the attraction, it is the total experience: the motion of the Moon’s shadow across the sky, or toward or away from you; the shape of that shadow; the surrounding twilight glow on the horizon; the sudden descent into darkness; the tear-jerking return to light; the presence of nearby planets and stars—all vary from eclipse to eclipse.

Then there are the sounds of any birds or wildlife (a big part of the 2001 eclipse in Africa) and of the wild people nearby as their excitement explodes like a diamond ring in the sky. What I find most impressive is seeing the landscape transformed from a normal one to an unearthly scene like no other you can travel to. That view changes with every location, from the altiplano of Chile in 1994 to the cloudscape over Antarctica in 2003.

Then there are the people you meet. We’ve been hosted by the Chilean army, by Kurds in southeastern Turkey, by people in Zimbabwe and by Libyans in their desert, all people who, at one time, we were supposed to distrust. Yet all were immensely hospitable and genuinely impressed and amazed at the eclipse we had come to their country to see. We were all friends sharing a common sky. That is a big part of the emotional experience that is an eclipse of the Sun. No, even considering the changes in the Sun’s corona with the solar cycle and variations in the diamond-ring sunbursts from differences in the lunar-limb profile, if every eclipse were in the same location every year, it wouldn’t be nearly as exciting. It is what’s down here on Earth—the location and the people—that makes all the difference. Having now seen 11 total eclipses (soon to be 12, I hope!), I’m also willing to take a few more risks in chasing the next ones. I’ve become a fan of seeing eclipses at the extreme ends of the path.

Rather than going for maximum eclipse duration at midpath, with the Sun high in the sky, I think seeing an eclipse with the Sun low on the horizon, rising or setting, makes for an even more spectacular experience. You see the shadow as a distinct inverted pyramid of darkness, with its apex containing the eclipsed Sun near the horizon. It was certainly the striking feature of the August 2008 eclipse in Nunavut last year, though to see it, we had to take to the air at the last minute to get above clouds. But that, too, is part of the attraction of chasing an eclipse. Each is, indeed, a chase, often suspenseful; some by ground treks, some by sea, some by air.

For this eclipse, I elected to go by sea to a point near the end of the path. (The photo, taken the morning of July 16, shows us anchored in the harbour at Huahine, one of the Tahitian islands. Eclipse chasing takes you to some pretty nice places!) The choice is risky—a low Sun is always more susceptible to cloud. But the reward, if we are successful, is a view of the eclipsed Sun over the Pacific, framed by the conical shadow of the Moon, a view I and a shipload of fellow umbraphiles have travelled around the world to experience. I’ll let you know how we do.