Our Astro Society was asked if we could lead a couple of sessions for a local Cub scouts group to prepare them for their Astronomy Badge.
A lot of the content is around the Solar System, so we thought that we'd assemble some appropriately scaled models. At a craft shop we were able to pick up Polystyrene balls in following sizes which are pretty close to representative.
10cm - for Jupiter
8cm - for Saturn (about 5mm too small)
to which we added a card 'hoop' for the rings - inside diameter 9cm, outside diameter 19cm
4cm - for Uranus and Neptune (c 5mm too large)
1cm - for Earth and Venus (1 & 1.5mm too large respectively)
0.5mm for Mars and Mercury (Mercury about 0.1mm too large)
If you can get a beachball about 1 metre in diameter, that will stand for the Sun.
We painted the 'planets' in appropriate colours using acrylic paints and they looked pretty good.
You can play with the scale factors on this Google Sheets on my drive
The calculation cells are locked, but you should be able to select your 'base' planet using the blue dropdown, and then select what size you want it to be using the left hand yellow cell.
The right hand yellow cell allows you to select the size you want for the orbits (obviously on a completely different scale to the planets).
I have a 15 metre tape that works well for Sun - Neptune, so Jupiter at 2.6m fits that scale.
Edited by gfamily, 12 December 2019 - 05:41 PM.