This week's Geek in Review is all about my love of science, especially astronomy, beginning with my first memory, looking at the moon when I was two or three years-old:
We lived in the Northwestern San Fernando valley, in a converted chicken coop on my grandparents’ property, which was one of many one-acre farms that shared space with weird-o hippie communes from the late sixties through the mid-seventies.
My dad was excited as he took me and my mom out of the house to stand beneath the walnut tree. Once outside, he didn’t even need to tell us why. There, rising over the pasture behind our house, was the biggest moon I’ve ever seen in my life. It was yellow and full and covered the entire horizon, like a drawing from a science fiction pulp novel. It was nighttime, but the glow of the moon lit up the ground in front of us as far as I could see, turning the leafless trees at the back fence into bony hands, reaching into the sky.
I stood between them in my OshKosh B’Gosh overalls, mom holding my left hand and dad holding my right, and stared at it while it slowly climbed into the sky. Though I was too young to understand the concept of beauty, I was still impressed; it was the biggest thing I’d ever seen in my life.
My dad picked me up and held me close to him. “That’s the moon,” he said. I can still hear the awe in his voice. In that moment, my life long love affair with space and science began.
By happy coincidence, I traded some e-mails with Phil Plait, better known as The Bad Astronomer, while I wrote my column, and I asked him if he could explain why the moon appeared to cover the entire horizon in my memory. He said:
You are a victim of The Moon Illusion!
You caught me in an expansive mood; I'm full of coffee and I just wrote 11,000+ words about black holes for my next book. So hang on.
The illusion is just that: an illusion. It can be really amazing, but in reality, even in your head, the Moon only looks two or three times bigger. This can be amplified by memory; some people swear they remember the Moon eating up the whole sky as you do (remember it, I mean, not that you eat the whole sky).
The illusion is a combination of two things. the first is the Ponzo illusion, where your brain interprets things as being bigger if it thinks they are farther away.
Second, the sky is not exactly hemisphere-shaped to our brains, it actually looks like an inverted bowl. Think of it this way: clouds overhead are maybe two miles up, but clouds near the horizon are a hundred miles away. So the sky looks bowl-shaped.
So when the Moon is on the horizon, your brain thinks it's farther away than when it's overhead. The Ponzo illusion kicks in, and your brain gets fooled into thinking the Moon is HUGE. As it gets higher, the illusion vanishes. If you actually observe the Moon with binoculars or with a 'scope, you can see it is no bigger on the horizon. In fact, it should look smaller because it's a few thousand miles farther away than when it's overhead.
It has nothing to do with foreground objects, atmospheric refraction or anything like that. it's a plain old illusion. I wrote a whole chapter about this in my first book, matter of fact. It was tough to research since people argue so vehemently over this topic. Fun though.
Phil's comments, and my ability to ask him for them, are yet another reason why we are so lucky to be alive at this moment. At what other time could I so simply and easily ask an astronomer such a noob question, and get an answer back so quickly?
This was one of those columns that easily could have turned into 5000 words, and I'm not entirely happy with the way I cut it down to keep it readable. I love science so much, and I am so fascinated by astronomy, that once I get going, it's hard for me to keep things brief. I didn't even get into Hyperspace (fish scientists FTW!) and all the stuff I learned about black holes and quantum physics when I was in my early twenties. I totally suck at math, and I've never taken anything higher than Algebra 2, so the fact that I can get even an elementary understanding of these subjects speaks volumes about the people who've written books about them.
If you're of a scientific mind, and you can communicate scientific ideas to guys like me, please keep on doing it. We're assaulted by pseudo- and anti-science on an almost daily basis, it seems, and enlightening the ignorant is the only way we're ever going to get off this planet before we destroy it.