Twinkle, twinkle little nuclear explosion

I had a father and his10-year-old son come for their first visit to the Observatory yesterday and this time I think I started them off right.

I’ve learned a lot during this first year of public observing sessions and one of the things I’ve learned is you can take people through three sessiond – 4 – 5 hours of actual observing time - and they still have no concept of what a star is. Since this stuff is taught in the schools I assumed that people would at least know the difference between a star and a planet.

But when I asked that question of one of the Scout groups I found they had absolutely no concept. I think the nursery rhyme “twinkle twinkle little star” sets the pattern for their perception of those admittedly faint and tiny-looking lights in the night sky. ( I suspect this is even true for many adults – and even if they “know” the science, they have no intuitive grasp of it because the stars do look so serene and small.) Among other things, most youngsters seem to think the Earth is a lot bigger than the sun – even when they know the sun is our closest star.

So I’ve decided whenever possible to start my visitors with a daytime visit to the Observatory and if my first experience of this is any indicator, it is really a much better way to begin. On an entirely practical basis this allows them to find my house in daylight and become familiar with the backyard where we’ll be spending time in the dark. It also means I can use this as the time to instruct them on telescope and binocular use and have them actually find targets using the finder on the scope. (I have done these introductions indoors with some groups – but this worked a bit better because there are more things at the correct distance to point at and focus. Telescopes don’t generally focus closer than 30 feet.)

More importantly, I can introduce the concept of scale models – and again, I’ve learned that 10-year-olds don’t usually know what a scale model is. So I start by talking about toy cars, before hauling out a 10-inch silver ball and saying that it is a scale model of the sun. In this case I asked the father to hold the ball, then I put a piece of number 9 bird shot – tinier than a BB – into the hand of the son, explaining that was the “Earth.” We then got out a tape measure and I had him measure off about 93-feet. Standing that far from his father with the 10-inch “sun” in his hand, it was easy for the son to see the ball. It was, of course, impossible for his father to see the “earth” as his son held it up. Bottom line here, though, is it’s fine to read about such scale models – it’s far better to hold these things in your hands and pace off the distances. Experience counts, I believe, in terms of burning basic knowledge deep into that 3-pound universe in our skulls.

We then moved to the observing deck where I had them use the Coronado PST to observe the sun in the light of hydrogen alpha and to make notes – particularly to draw on a prepared disc what they saw on the sun – the location of sunspots, phages, and prominences. This drawing business is not aimed at scientific exactness nor artistic goals. The idea is simply to get them to observe closely. The pair spent a pretty intense half hour doing that and discovering more and more as they did it.

At the conclusion the father asked what I thought were the main points to take away from the experience. (He is homes-schooling his son.) I said I would send an email – as I always do – trying to wrap up what was covered in an observing session and reinforcing the facts. (Simply hearing things – and experiencing some – is no way to remember. You need to reflect and digest. In that email - I responded:

You asked what were the most important points we covered. I think they are these:

1. The sun is huge, the earth is tiny, and there’s a ton of empty space between the two. The model you used was on a scale of one foot equals a million miles. The ball you held was 10 inches, the Earth was about 2.5mm, and I had your son stand 93-feet away.

2. The sun is our nearest star and all stars are dynamic, constantly changing objects. You saw some of that as you observed sunspots, solar prominences, and phages. It’s not the nice, calm, quiet disc we may picture in our mind. It’s constantly changing and – of course – it is fueled by the same power that fuels a nuclear bomb – only it’s much, much more powerful than any bomb and it’s going off continuously.

3. Observing is a skill. You have to sit down, get comfortable, take your time, and be patient. Drawing what you see is helpful – even in the dark – and we’ll do more of that because when you draw you see more – it focuses your attention. The result isn’t important. The process of drawing is. You are trying to learn how to see.

4. The main function of an astronomical telescope is to gather light. Magnifying things is important also, but often receives far too much emphasis. A telescope gathers light by catching it on a special mirror and reflecting it to a focus, or by catching it with a lens and bending it to a focus.

I know it isn’t going to be possible to star every group with a day time session, but I’m going to try. And when I can’t, I’m still planning to use my Sun/Earth model as an attempt to put into perspect what all those twinkling “little”stars really are.