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Forum » SpaceEngine » General Discussions » Can I unlock a moon? (In terms of tidal locking) (^)
Can I unlock a moon? (In terms of tidal locking)
Wes1883Date: Friday, 20.03.2015, 09:16 | Message # 1
Group: Newbies
United States
Messages: 2
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Hello all.

So this might be a simple question for you all, but I only recently got into using Space Engine and could not find an answer through dozens of searches. I use this wonderful program to simulate fictional worlds, sometimes for fun, but mainly to get a real idea of what the horizon might look like on an alien planet under specific circumstances for some science fiction short stories.

As the title implies, I want to figure out how to eliminate a moon's title locking from the simulator. For example, if I wanted Jupiter's moon Io to stop being tidally locked, is there a way to do that in the editor? If it helps, the scenario I'm looking to simulate is a moon that rotates once every ~30 hours, has an orbital period around its planet of ~40 days, and can experience both a regular sunrise/sunset and a "moonrise/moonset," except in this case it would be the parent planet rising and setting. Kind of like if you're sitting on the surface of Hyperion orbiting Saturn, except significantly less wonky.

Thanks in advance for any help. I'm totally lost, and figuring this out is super important to me!
WatsisnameDate: Friday, 20.03.2015, 11:06 | Message # 2
Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
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You can, yeah. If you try to do this through the editor (select planet, press escape --> editor --> edit planet), it won't work because for a tidally locked world the engine is implicitly ignoring the rotation period.

Instead you'll need to tell SE to use the rotation period you give it by exporting and editing the planet file directly. The edits you need to make are extremely simple, but the exporting process is a bit more involved and I'll refer you to the MOD: Creating a Planet thread for those details. But basically all you have to do is add in a line for "RotationPeriod" just above the lines for Obliquity and EqAscendNode, and give it the value you want. Refer to the code of a non-locked moon for comparison, or see below:


Moon    "7.1"
     ParentBody     "7-7.1"
     Class        "IceGiant"

     Mass            34.93201
     Radius          25455.93
     InertiaMoment   0.2094921

     Oblateness      0.006923325

     RotationPeriod  18.18756
     Obliquity       -1.497454
     EqAscendNode    62.02771

     Albedo          0.6
     Brightness      2
     Color          (1.000 1.000 1.000)

Note this is purely for procedural objects, not solar system bodies.
Hope that helps, but feel free to ask if you run into any problems or have more questions. And welcome to the forum. smile

SpaceWesDate: Friday, 20.03.2015, 12:36 | Message # 3
Group: Newbies
United States
Messages: 2
Status: Offline
Thank you so much for the response!

Following your instructions for where to add the line (after downloading Notepad++ as the linked page suggested) and abiding by the guidelines provided, I managed to create my own moon orbiting Jupiter with the proper custom parameters! Now that I know the basics, I plan to follow more tutorials until I've created my own solar system and planets to the specifications I need. This is an incredible tool that I know is used for more than just visualization, but it's already proved invaluable in helping me really see what it would be like standing on another planet.

Thank you again!
Forum » SpaceEngine » General Discussions » Can I unlock a moon? (In terms of tidal locking) (^)
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