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Serendipitous indeed!

My "Serendipitous Sidewalk Astronomy" episode last night At Allens Pond Wildlife Sanctuary turned out to be serendipitous for me as well. I like to call what I'm trying to do "planned serendipity.' I understand the contradiction in terms, but the idea is to stack the deck somewhat so that nice, unplanned things can happen.

7.17.07_moon_venus.jpg

Last night my program was called "In the Footsteps of Galileo" and the planned part of the serendipity was to get folks to look at the crescent moon, Venus, and Saturn, all pretty close together in the western sky – weather permitting. The weather cooperated for the moon and Venus - Saturn was obscured. I pointed the little five-inch Celestron NexStar at Venus and let it track while I gave a one-minute spiel on Galileo and the strongly held belief of four centuries ago that everything – everything – revolved around the Earth.

Then I let them take a peek through the scope and that's where the real serendipity came in. Everyone thought they were looking at the crescent moon when in truth they were looking at a beautiful, crescent Venus! It had never occurred to me that someone would mistake this for the moon! To begin with, telescopes should make things bigger, not smaller, and the object in the telescope, while crescent, was smaller than what you could see with the naked eye. But everyone in my little group of first-time visitors thought they were seeing the moon. Cool!

When I told them it was Venus they were seeing there was general disbelief at first. These were bright people. One was a school teacher, another a geologist visiting from Montana. I think she was the one whothen asked me if I were a professional astronomer. "No." I answered. "Oh," she teased, "then we don’t have to believe anything you say."

"Oh please don’t believe me, Believe your eyes!" and I gestured to the telescope. Wish I had had enough presence of mind to say "read the book of nature" as Galileo read it – or even quote Shakespeare:

"And this our life, exempt from public haunt,
Finds tongues in trees, books in the running brooks,
Sermons in stones, and good in everything."

The sermons were there last night in the "stars," for Venus was just one of the wandering stars 400 years ago, and a very bright one , indeed. But the serendipity that made this all work – allowed them to experience a little of the incredible surprise Galileo must have felt when he first pointed a telescope at Venus – was the proximity of the crescent moon. The moon and Venus were close enough in the sky so it really was difficult to know which one the little telescope was pointing at.

I stress "little" here because any modest instrument will show you the same thing. In fact, I have reconfigured a cheap refractor so it performs as Galileo's 0ne-inch telescope did and delivers about 20X and they viewed Venus in this as well.

And, of course, Venus is now in a fine crescent phase that almost exactly mimics the moon. Quite impressive, really, even to an experienced observer.

And most importantly, it was Galileo's discovery that Venus displays such phases that was one of the key nails in the coffin of the old, earth-centered, world view. One of the best ways to explain these phases is to imagine that Venus is going around the Sun – not the Earth – and in an orbit that is closer to the Sun. This, of course, is the case. Right now Venus is overtaking the Earth because it's orbit is smaller and it's between us and the Sun. As it does, the side of the planet facing the Earth is dark and just a tiny part of the side of Venus lit by the Sun is visible to us. In a few weeks Venus will be too close to the Sun for us to see at all. But right now we can still see a beautiful, crescent-shaped sliver of it.

Oh I showed them some of the other pieces of Galileo's evidence – the moons of Jupiter, for example, certainly illustrate that at least four "planets," as Galileo called them , are circling that "star," not the Earth. And the moon itself, pock-marked by craters and mountain clearly visible in a small scope, put a real kink in belief of that time that all "heavenly bodies" were - well, heavenly. That is, they were perfect, smooth, spheres,

I didn't preach this sermon. I did my best to simply let them read the sermons in the stars. Ok – it's hard for me to keep quiet. But I don’t think anyone will remember what I said. What they'll remember is that wonderful little piece of serendipity when they looked through a telescope at what they thought was the moon and instead it was Venus. That should fix in their minds the idea that Venus goes through phases much better than any words of mine, or text for that matter.

Oh - we did not get to see Saturn. It was hidden in some murky clouds along the horizon at first and by the time I searched for it later, it had gotten to close to the horizon to see. And speaking of murk, a bit of water vapor in the sky isn’t bad for seeing bright planets, but it plays havoc with stars and faint nebula, so I started packing up around 9:15. There were plenty of high clouds around and the forecast had called for there to be more.

Still, I stood there with Ben and Martha Guy, to members of the Prime Time group, and we watched the stars come out and Martha noted how Ben didn't think this was g a good enough night to see anything and how she liked it when it was a bit cloudy and only the bright stars were visible because it was easier to identify them that way. I confessed that I was more like Ben. Through most of my years as an amateur astronomer if I looked out and saw marginal conditions as we had then, I would have stayed inside. It's only because I am sharing my observing with others that I go out under such lousy conditions.

So we stood and talked about what stars we could see and I put the three telescopes and other equipment in the car and we continued to talk until I noticed that the large clouds to the south weren't clouds at all, but the first faint billows of the Milky Way. Thatw as the second piece of serendipity of the night. I brought out the 8-inch and we took a quick look at a couple of regions of star birth down there towards the center of our galaxy, as well as M22, a wonderful globular.

So what have I learned from this? First, get out and try. Bad nights can frequently be good – even great. And second, show people Venus when the moon is near it – especially when they are both in crescent phase. It's just great fun!

Posted by Greg Stone at July 18, 2007 07:45 AM Comments? Please email me: gstone@umassd.edu

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