[Squeakland] sun-earth-moon

Fernando nandofv at yahoo.es
Fri Feb 17 05:53:38 PST 2006

Another approach:
  I'm using this simulation in Primary School, third level (eight years  old). Children try to simulate [1] Eatrh's spin on his axis and [2]  Eatrh's rotate around the Sun. Well, this is very interesting because a  lot of them still think the sun rotate around the Earth!!
  With basic eToy, the construct and investigate these two processes.  First they paint a circular solid Base and then embed the Earth in this  Base (Randy's solution is amazing but they don't know degrees).
      [1] Go and Rotate for Base scketch
      [2] Only Rotate for the Earth 

Nicholas Bennett <nicholasjbennett at hotmail.com> escribió:  randy,

I had done a sun earth moon system once and found that one could set the 
rotation center fairly easily (I think one of the halo menu choices maybe, 
also there I think you can tell it to display the rotation center and the 
forward vector which can help visualize things).

I had used the embedding as described below, but found that if I simply 
embedded earth in sun the earth would be 'unselectable' when it did not 
overlap with the sun - which made it awkward if you wanted to go back and 
add the moon later. I ended up painting the 'orbit center' of my 'orbiters' 
as a small dot in the orbiters sketch - a bit strange maybe but it made it 
very clear where the rotation center should be and ensured that the orbiters 
stayed selectable when embedded.


>From: Bert Freudenberg 
>To: Mailinglist Squeakland 
>Subject: Re: [Squeakland] sun-earth-moon
>Date: Thu, 16 Feb 2006 19:08:22 +0100
>Am 16.02.2006 um 16:43 schrieb Randy Heiland:
> > Is it possible to squeak planetary motion?
>Yes. You have to embed the moon into the earth (you find "embed" in
>the halo menu). Then, when you move the earth, the moon already moves
>with it.
>Here's an example:
> http://squeakland.org/project.jsp?http://impara.de/~bert/projects/
>- Bert -
>Squeakland mailing list
>Squeakland at squeakland.org

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