NSW2012: Preparing a solar system model

posted: 2003 days ago, on Thursday, 2012 Jul 26 at 22:57
tags: astronomy, outreach, NSW 2012, Ed Foster.

In preparation for next week's National Science Week, Ed Foster and I assembled one of Star Wader's Portable Solar System Models (shown on the right).

This model, designed by Neville Young, is clearly going to be a very valuable tool for explaining the visibility of the Sun and planets, and much more.

The set-up took about 45 minutes and was quite straight-forward. The assembled structure seems flimsy at first, but this is only because I'm used to more solid telescope mounts and tripods - it works just fine.

The planets - except for Mercury and Mars - are plastic balls, which clip easily on to the "orbits", which are thin blades of spring steel that snap into grooves cut into the plastic electrical conduit pipes. The Mercury and Mars place markers, however, are dodgy. These are soft plastic hemispheres and require some dexterity to attach. However, having spent several years myself looking for plastic balls to represent planets, I think the Star Wader's solution is very good.

Knowing where to place the planets can be tricky. No great accuracy is required (or attainable) so it would be sufficient to use a diagram such as that generated by the excellent heavens-above.com, or given in Fred Schaaf's column in Sky and Telescope. However, in the long run, this will prove to be impractical.

To solve this, I constructed a circular scale showing ecliptic longitudes [download the PDF] which is mounted behind the Sun-marker. The cardinal points (solstices and equinoxes) are aligned with the supporting conduit pipes.

Then, I compiled a table of planetary geometric heliocentric ecliptic longitudes (at two-day intervals) [download the PDF] which makes correctly placing the planets for any date from today until end-2013 very easy.

With that task done, all that remains is to use the PSSM during an outdoors outreach event. I can't wait!

Caption: (top, left) Ed kicks off the assembly process. (top, right) The completed model. (bottom, left) Looking across the solar system. (bottom, right) checking that our planet settings are correct, using the diagram from the September Sky and Telescope, and that from heavens-above.com. The inset image shows the

nothing more to see. please move along.