# Help figure out the planet M [closed]

let's imagine there is a planet named M. it has 2 or 3 moons and one of them is as big as a moon can be. the moon is in lag range 1 and it blocks the light of the star for at least half of the year making the whole planet night time. the planet itself takes 1000 days to orbit its star. and days and nights are very long.

these are the concerns:

1: how big and how close/far should this big moon be for the situation above to work?

2: how big can the planet be in order for humans to live normal lives.

3: will vibrant life be possible on such a planet?

4: if the light is blocked by the moon, won't it freeze the planet?

5: how can I have very very long night but still have good temperatures?

6: if the question number 4 is correct, can I use the moons to duplicate the effect on IO and produce volcanos to warm things?

7: if the planet is tidally locked with its biggest moon, will there be ALWAYS darkness or will there be also day time?

p.s: I could even change the star, this whole system is imaginary.

and i CANT seperate these because then i would have to copy and paste ALL the details of the imaginary planet and its orbit and its moons over and over again. wouldnt that be worse ?

## closed as unclear what you're asking by ZeroTheHero, WillO, peterh, Jon Custer, YashasJun 10 '17 at 3:25

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• Would Worldbuilding be a better home for this question? – Emilio Pisanty Jun 9 '17 at 21:31
• I assume "lag range" wasn't supposed to have a space because lagrangian points makes this less nonsensical. Read here: en.wikipedia.org/wiki/Lagrangian_point the L1 point is determined by the mass of the planet and the mass of the star. – user273872 Jun 9 '17 at 21:40
• This seems like an awful lot of separate questions, not all of them terribly related to each other. – WillO Jun 9 '17 at 21:55
• (And many of them not terrible well focused.) – WillO Jun 9 '17 at 22:02
• The question would be on-topic on Worldbuilding, but it is way too broad in any case. If you can narrow down the question (or ask several separate question instead of one big one), it'll probably be accepted there. – ACuriousMind Jun 10 '17 at 13:40

1: Mass of the planet and mass of the star determines the distance and then it's just a geometry problem, draw a triangle between the star and the moon and a point on the planet, think about eclipses.

2: I think this one is about gravity, to big and they wont be able to move around.

3: Not probable. A 1000 day orbit means that it's about 3 times further from its star than we are from ours, so depending on the temperature of the star it's likely out of the habitable zone.

4: Shadows for half the year will definitely cool things down.

5: Possibly a massive green house effect?

6: you have multiple moons so probably can squeeze things, but wouldn't it squeeze the small moons harder? At this point i'd be hooping for an endor moon.

7: I dont' think the rotation of the planet is relevant, if the moon is stuck in L1 and big enough to eclipse the planet there will be darkness year round no matter how it spins

• Wouldn't number 3 and number 5 work with each other? – Maxwell Jun 10 '17 at 14:11
• what if we could decide how the star could be? – Maxwell Jun 10 '17 at 14:18

As per your question 1, the Lagrange point $L_1$ is unstable. Thus it seems difficult to realistically have a very large Moon staying there on astronomical times. That puts a bit of a wrench in your idea! Answering your questions is not trivial in any case because the distance between $L_1$ and the star is the solution of a polynomial equation of order 5. Usually, the mass of the object at $L_1$ is taken as much smaller than all the others, and a simple formula can be obtained, but since you want as big a Moon as possible… I could try whipping my Mathematica.

• So IF the largest moon was further away and another moon was in lagrange point then what? it has to be able to cast pretty big shadow on the planet. – Maxwell Jun 10 '17 at 14:28
• Instability means that the moon would quickly move away from the Lagrange point, ending on an orbit which would shadow the planet every now and then, like eclipses do. As to whether one could arrange the planet masses and the distance to the Sun in such a way that the moon at L1 could occult the Sun, as I wrote, I would need to put my brain to work for way longer than it took me to write these messages! But is it worth figuring it out considering that in any case the moon could not stay there? – user154997 Jun 10 '17 at 14:45
• Thank you very much for the time and thought. And yes if the moon could stay there for half of the orbit or even one-third of the time it would make a big difference, don't you agree? or perhaps anything better comes to your mind to have planetary night time for a long time? – Maxwell Jun 10 '17 at 14:51
• The simplest idea coming to mind would be to have the planet rotation axis nearly pointing toward the Sun. Then the best part of one hemisphere would be permanently be in the night, while an equatorial zone would see day/light alternance, and the rest of the other hemisphere would see permanent daylight. – user154997 Jun 10 '17 at 15:02
• That's the same as being tidally locked right? Anyway, this idea can't be done for this planet because it needs cycles and lush forests, if it were to be looked like the moon is to earth, then one side would be frozen, another side would be hell, life would only be at the hemisphere. – Maxwell Jun 10 '17 at 15:10