So let's say I have rogue planet the size of mars. I want seasons roughly the the same as Earth and a "sun" that appears similar to our sun from the surface.

How big would the Star need to be? How far away from the planet would it have to orbit?

I also want a moon. I'm thinking maybe 2 bodies of equal size orbiting on either side of the planet would work, but not sure...

Edit - The planet is in reality a space ship with an habitable exterior. The race is capable of artificial gravity and fusion. I Need a sun and moon object in the sky to replicate the appearance of an earth environ on the surface of the ship.

I need to know the minimal distance/size that i could make these from the ship to create the illusion.


closed as off-topic by StephenG, F1Krazy, Josh King, sphennings, Vincent Mar 7 '18 at 16:19

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  • $\begingroup$ You should have the planet orbit the moon and then have the sun orbit the planet, but not the moon. That seems like it would work \s $\endgroup$ – ArtisticPhoenix Mar 7 '18 at 4:45
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    $\begingroup$ By definition a "rouge" planet is unbound, in otherwords its not bound to a sun, which is why its rouge. $\endgroup$ – ArtisticPhoenix Mar 7 '18 at 4:47
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    $\begingroup$ I'm confused. What's wrong with just having the ship orbit a sun when it doesn't need to move around? $\endgroup$ – Aify Mar 7 '18 at 7:42
  • $\begingroup$ Your original question made no mention of the goal you had (a sky like Earth for your ship inhabitants) or even of the "ship". This is such a drastic change you should close your question entirely and ask a completely new one (more carefully explained !). An edit is inappropriate in this case. $\endgroup$ – StephenG Mar 7 '18 at 15:46
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    $\begingroup$ I'm voting to close this question as off-topic because the edit is too drastic a change and would completely void the two existing answers made in good faith. $\endgroup$ – StephenG Mar 7 '18 at 15:48

Any self sustaining star will be way more massive than Mars. This makes impossible for the star to orbit the planet: it will always be the planet to orbit the star.

Or, better, the center of mass of the system will always be deep into the star.


Change your inertial frame of reference.

If you treat the Earth as a stationary object, then the Sun will be orbiting the Earth roughly once a day. This will make the math needed to explain the motion of the other planets much more complicated, because the motion of the planets will change from being roughly elliptical to a spiral-thing (as can be seen in this image).


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