April 20 was Astronomy Day. Bernard asked the club to suggest activities, so I proposed operating a telescope on a street corner downtown. Kurt Hillig graciously loaned me his 10-inch Meade Schmidt-Cassegrain and tripod. Other members mentioned that they had used the corner of Liberty and Ashley before [this is in downtown Ann Arbor, Michigan].
To maximize pedestrian traffic, I chose the northwest corner of the Diag, at State Street and North University Avenue. I was too busy with the crowd to fuss about transparency or seeing, but the weather permitted us to see the Moon and Jupiter until 10:30 PM. For a while we could see Saturn and Mars too. The rooftops across the street provided reference points to help people find them for themselves.
In two hours about 50 people stopped by. Some returned later for a second look; some told their friends. Everyone was enthusiastic and grateful. Here are their most frequent questions and my answers to them. Some of these took me by surprise. John Dobson may have something to teach all of us about sidewalk astronomy.
Q. [curious stare from a distance]
A. I’m looking at Jupiter! Would you like to see?
Q. Why are you here tonight?
A. It’s Astronomy Day. I want to show a few things to a lot
of people.
Q. Aren’t the streetlights rather bright?
A. We would need a darker location to see galaxies and nebulas,
but even here we can see planets.
Q. Do we owe you any money?
A. No, this is a public service of the Lowbrow Astronomers.
Q. How do you know that’s Jupiter?
A. That’s where Jupiter is supposed to be in its orbit,
and it looks like Jupiter is supposed to look. (A few
words about the Ecliptic, twinkling, and the naked-eye
appearance of each planet might have been more helpful.
Maybe I could have invited people to draw conclusions from
their own observations.)
Q. Why are its moons all in a line like that?
A. We’re almost in the same plane as their orbits.
Q. Is that the Red Spot?
A. Yes! (skyandtelescope.com had predicted a Red Spot transit
between 8:30 and 10:00 PM.)
Q. Why does it move out of view so fast?
A. We’re magnifying the rotation of the Earth. (Since I had
not used this telescope before, I had some trouble with the
clock drive at first.)
Q. How powerful is this telescope?
A. We’re using 150x magnification, but aperture is the most
important thing. With a 10-inch telescope and some practice,
you can see about 500 different galaxies. (Even if I had
prepared hard numbers for resolution and limiting magnitude,
I doubt whether they would have been appropriate for the
audience.)
Q. How much did it cost?
A. It’s not mine, but I guess it was about $2000. (This may
have been somewhat discouraging. A Dobsonian would have
shown how inexpensive a good telescope can be. At least I
should have talked about them.)
Q. When will you do this again?
A. I’d like to try again in a month or two. Maybe I can get
some other club members to help. (The first quarter Moon
has a surprising capacity to amaze the public....)