School visit: scale of the Universe

I went on a school visit this week to Springfield Technology College - a secondary school with a focus on science/technology just to the north of Portsmouth.

Kudos to the teachers at the school for suggesting I speak with two groups one after another - thus giving me maximum outreach impact for my travel.

The first group I spoke with was 60 YR7 pupils (11 and 12 yr olds). I chose to talk to them about "The Scale of the Universe" as it allows me to talk about planets and use my fun solar system model, but also link to cosmology and the types of science we focus on here in Portsmouth ICG.

I started with the inflatable solar system model. As previously used at out BBC StargazingLIVE Event at the Spinnaker Tower, and already on their 3rd school visit.

Inflatable planets decorate the Spinnaker Tower (in an approximation of the actual layout of the Solar System in Jan 2012). 

To introduce this to children I start with the Earth. I ask them to think about distances they are familiar with. I ask things like who has been on holiday a long way away, and if anyone has done any long walks or car rides. I then ask them to imagine shrinking the whole Earth down to the size of the model. I ask for a volunteer to hold the Earth.

I should point out at this point, that while the inflatable solar system is pretty fun as a demo, it's not an accurate scale model in any sense. I made the below cheat sheet for myself to remember the real relative sizes.

On the scale of the Earth in the model, the Sun should be 36m across. This isn't too far of the scale of the classroom which I will point out. Obviously it's not possible to have a beach ball that big, so we'll use the one provided (which is almost a metre in diameter and which they were very keen to get picked to hold!). On this scale the Earth should really be about 1cm across (and I have a little ball on a cocktail stick which is about this size). I next suggest the student who is holding the sun that he walk about 1km  away to make an accurate scale model (just kidding!). From Springfield school this was about the distance to the train station which was useful. So instead we won't really make a scale model, but we'll put the planets in order. Then I let them pick planets they like and tell them a little bit about each one in turn (if you can see it, some tiny fact).

I'll usually demo the real Earth-Moon distance when that comes up - asking them to tell the student holding the Moon how far away it should really be (they always guess too close - as would have I before seeing the real answer).

After this part of the talk I moved to videos. I showed them the real scales of the planets using a video. You can find lots of these on YouTube (which I downloaded using an internet service in case I couldn't get online for the talk). The one I used is this one:



Which I stopped at about 55 seconds on the image of the Milky Way. So then I talked about galaxies - about how many stars might be in each galaxy and how most of them probably has a planetary system.

To go further up in scale I use the fly through of the Sloan Digital Sky Survey DR4.



Which is great because ICG are involved in this survey (which I meant to tell them, but I think I forgot). It also ends with the CMB so we could talk a bit about cosmology and the birth of the Universe.

At this point I get a lot of questions. Mostly on cosmology - what's before the Big Bang, outside of the Universe etc. great questions. After a while of that I remind them they can ask me about other topics in astronomy - doesn't anyone want to know about black holes or aliens. Which led to a discussion of spaghettification. Always fun - especially when you're 12! Final question - what would happen to a plate of spaghetti which fell into a black hole (and we find out the class joker!).

To end I gave out my colour the solar system scale model - perhaps a bit young for them, but you never know. I made a new version you can print on just one sheet of paper.

I enjoyed it and I think they did too.