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Author Topic: A couple of newb issues  (Read 4432 times)

BaxterT

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A couple of newb issues
« on: April 18, 2012, 07:17:34 AM »
Moons?
I can't seem to add moons to planets. How to you do that? I've selected the planet I want to add moons to, but it keeps trying to assign their orbit to the nearest star.

Delete mistakes?
How do you remove something you decided you didn't want?

"Landing"??
What the heck is that, and how do I remove it?

Rings?
How do you add them?

Thanks!!!

Bla

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Re: A couple of newb issues
« Reply #1 on: April 18, 2012, 08:02:16 AM »
Moons?
I can't seem to add moons to planets. How to you do that? I've selected the planet I want to add moons to, but it keeps trying to assign their orbit to the nearest star.
Try placing the planet further from the star and/or placing the moon closer to the planet.

Delete mistakes?
How do you remove something you decided you didn't want?
If it is an object (like star, planet...), click it and click "Delete" on your keyboard. If it's dust, you can't delete it, except if you go into the menu on the left and click the "X Dust" button below the collision/accuracy modes, but that will delete all dust in the simulation.

"Landing"??
What the heck is that, and how do I remove it?
If you zoom in on an object enough, you will land on it, so your camera is turned like as if it were on the surface looking at the horizon. Click on the landing point and then click "Delete" on your keyboard to delete it.

Rings?
How do you add them?
Click the "Add tool" (the planet icon in the bottom left corner), then click "Rings" (the button furthest on the right), then click on the body you want the rings to orbit, and then click the ring you want in the menu. Like this (it doesn't matter when you click the object, as long as you click the buttons in this order):

BaxterT

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Re: A couple of newb issues
« Reply #2 on: April 18, 2012, 06:02:11 PM »
Thanks! I'm still throwing planets out of my systems... but it's FUN!!

Dan Dixon

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Re: A couple of newb issues
« Reply #3 on: April 21, 2012, 01:42:10 PM »
Thanks! I'm still throwing planets out of my systems... but it's FUN!!

If this happens you're likely turning the time step up too high. We hope to address this very common issue in Universe Sandbox 3.

And thanks to Bla for all the great answers!

Vanamonde

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Re: A couple of newb issues
« Reply #4 on: May 23, 2012, 03:51:15 PM »
I'm experimenting with creating multi-star solar systems, and having some baffling (to a newbie, anyway) problems.

I can get 2 stars to orbit each other reliably, but a third often takes off on a hyperbolic course even though I'm using auto-orbit placement. How is using the box mode to set them as binaries different from just placing 2 stars, and might that be part of the problem?

Possibly I'm not grasping the concept of a Hill radius, but when I put orbiting objects within them, they still sometimes wander away from their primaries and become satellites of the main star. Is it a glitch or am I confused or what?

Hope these aren't dumb questions, and thanks for any help you can give.

vh

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Re: A couple of newb issues
« Reply #5 on: May 23, 2012, 03:58:06 PM »
Hill Sphere is pretty inexact, probably due to timestep. (Timestep is when the game calculates the motion of objects every frame as opposed to every instant in the real universe). Try putting moons far inside the hill sphere.

Getting 3 stars of equal mass into an orbit is a bit tricky, i've managed to get to into a semi-stable orbit

Place two stars, ctrl-a, binary orbit, make barycenter

Place a third star, select barycenter and new star, binary orbit them
« Last Edit: May 23, 2012, 04:03:57 PM by mudkipz »

Vanamonde

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Re: A couple of newb issues
« Reply #6 on: May 23, 2012, 04:20:21 PM »
I've placed moons at half the Hill radius or less and it still seems to happen, but I think you answered my question when you explained that these aren't absolute guarantees of stable orbits. I just need to experiment a bit more, I guess.

Does the barycenter thing actually put a gravitating object into the simulation? Or just what does it do? And the trinaries I've been trying to set up are like (I believe) most real trinaries are arranged: two fairly close stars orbited by a farther and smaller third. Don't know if that makes a difference. I did see on another thread that the simulation doesn't always take a co-central star's gravity into consideration in multi-star systems. Does the method you're suggesting get around that?

Thanks again.

vh

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Re: A couple of newb issues
« Reply #7 on: May 23, 2012, 06:22:35 PM »
The barycenter is a measure of the center of gravity of more than one objects.

Also, yes, the method i suggesting gets a binary system orbited farther away by a star. Trinaries are just hard to get i suppose, it rarely happens that they orbit perfectly in a ring in nature. If you placed them exactly with the coordinate system it might get that to work properly, but any orbiting planets would probably disrupt that delicate balance.


Vanamonde

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Re: A couple of newb issues
« Reply #8 on: May 23, 2012, 08:44:59 PM »
Sorry, I wasn't clear. I know what a real-life barycenter is, but what does it mean to put one in the simulation? I mean, any two objects in the simulation will have a barycenter just because of the forces involved, but what is different about hitting the simulation's button to place one?

I seem to have figured out trinaries: I was confusing the adjacent time step and simulation speed sliders, so I was losing stars because I was telling gravity to exert itself only once every year or so. I still can't figure out why my moons wander away like inattentive sheep, though.

Still, it's fun just watching things go haywire.

Darvince

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Re: A couple of newb issues
« Reply #9 on: May 23, 2012, 09:53:23 PM »
When you hit the button to create one, it places the barycenter of the selected objects. Currently, however, this barycenter can wander around because it is affected by gravity as well, if there are very massive objects that are not included when you place it. The barycenter is useful for placing objects orbiting a binary pair, and for some other things like viewing the system from its center.

Your moons probably wander away because the timestep is more than about 1/20th the time of the moon's orbit.