Hello everyone!

Here is my latest creation, an orrery displaying the three inner planets.

http://www.youtube.com/watch?v=0pv04_gqBOk

I rounded off the real orbit period numbers so that they would be easier to recreate using lego gears.

The real orbit period for Mercury compared to Earth´s orbit period(1 year) is 0.241 and I rounded it to 0.25.

Venus´ real orbit period is 0.615 and I used 0.6.

To figure out what gears I should use I divided 1 with 0.25 for Mercury and 0.6 for Venus(1/0.25 and 1/0.6).

This got me the numbers 4 for Mercury and 1.66.. for Venus(1 year on earth is approximately 4 Mercury-years and it is also approximately 1.66.. Venus-years)

The moon should complete 12 revolutions per orbit (12 months a year) but i just had the very small space on the ´´arm´´ that holds Earth to place gears on so the closest I could get was to have it completing 11.66.. revolutions/months per year/orbit.

Edited May 19, 20159 yr by Olof

Nicely done. For sure the kinematics are not trivial and it must have taken some serious time/tinkering to get it right.

This reminds me of a recent trivia question: which planet has its year shorter than its day?

Also, with the various 'planets' available from the StarWars sets, I wonder if one can possibly build a larger version with more 'precise' kinematics.

Edited May 16, 20159 yr by DrJB

Awesome! Keep going, this would make an amazing creation if you could put in all the planets!

Thanks DrJB and pinioncorp!

I agree that it would be very nice to add more planets, but unfortunately it would require more turntables. With my current parts it is actually possible to add Mars but it would be very diffucult. Adding some more realistic planets would also be a relly nice addition.

The answer is......... Venus! And nicely done, maybe you could try to make the other planets spin too, but i guess that might be too hard at this scale.

Edited May 16, 20159 yr by Coola1

Thank you Coola1! Well, I think it is too hard to make all the planets spin. Though I have thought of making earth tilt its 23 degrees just like it does in reality.

Here is the original video: https://www.youtube.com/watch?v=0pv04_gqBOk

Update: I have now added the tilt of Earths axle. I tried to come up with a way to make the axle always staying in the same directon(adding seasons) but there was so little space to work with. Also ( as you may see in the video) it deoesn´t operate very smoothly beacause every time the moon is on its way to the sun it have to "climb" and on its way away from the sun it is in a descent.

http://www.youtube.com/watch?v=CttMtsUMqus

I also tried adding Earths rotation around its own axle. After just trying making it spin 60 revolutions per orbit I realised that the friction and thus the force to drive it was to great. This caused the gears to slip off eatch other.

Here is a picture of It.

Edited May 19, 20159 yr by Olof

Very nice model! Don't stop at current stage! :)