According to the Frontiers Saga, a moon (like Haven or Adlair) spends 50% of its orbit in the shadow of its planet, also known as "the long darkness". The other 50% of the time, the moon has a regular day/night cycle. (Not necessarily 24 hours, but very regular.)
All of this is dead wrong. (Sorry. It really bugs me.)
First of all, the "long darkness", as the dark half of the cycle is called, does not exist. This "long darkness" would be the equivalent of a lunar eclipse. If you have ever watched the Moon get into the Earth's shadow, you'll know that it is a matter of mere hours, and that it does not happen every time the Moon passes behind the Earth. The reason for the rarity of lunar eclipses in our system is that the lunar orbit isn't on the same plane as Earth's orbit around the sun, but on a plane that's angled towards the ecliptic by around 5 degrees. Thus the Moon usually passes under or above the Earth's shadow instead of passing through it.
Of course, a planet-moon-system with a gas giant is a slightly different story, because a gas giant has a much larger shadow than a small, rocky world like ours. Still, it doesn't change the fact that the lunar orbit is mostly in the light, not in the shadow of its planet. (I could draw conceptual sketches tio illustrate this, if needed.)
Another thing to consider is tidal lock. What does it mean? Well, look at our moon, which is a prime example for this. It always shows us the same side. Always. Both its orbit and its rotation take exactly the same time. Thus, a day-night-cycle of our moon is as long as its orbital time - approximately 28 days. A tidal lock is not an unusual phenomenon, either. All big moons in our solar system are tidally locked with their planet, as well as many smaller ones, too. It stands to reason that other solar systems would be the same. (As a matter of fact, there's a reason why most moons are in a tidal lock, but I'm too lazy to try to explain something I can barely follow in a language that is not my native one.)
Overall, this leads to a very different situation for any inhabitable moon: Each of them should have a very long rotation, a short additional darkness (lunar eclipse), at least on occasion - and a very bright parent planet that shines like our moon - and goes through the same phases. (Yes, on the Moon, you can see a full Earth, gibbous Earth, half Earth, crescent Earth and New Earth - it's just the same as we see the moon phases.) The only difference is that the planet is probably much bigger than our moon, even when viewed from the inhabited moon. (This would be especially true for moons in close orbit, or those orbiting a gas giant.) Depending on the circumstance, the planet might take up most of the night sky, and cause no little illumination. However, this light would be pretty cold. (Compare the sun's surface/photosphere temperature with the temperature of any planet. See a difference? Yep, just a couple thousand degrees Kelvin. If you want to do an experiment, use a traditional light bulb for the sun and an LED light bulb which emit the same amount of light for the planet. The traditional light bulb is much hotter, even though it emits the same amount of light.)
I agree with you.
50% of the orbit behind the Gas Giant (as in behind its orbital path) is correct / but 50% of the orbit in the shadow of the Gas Giant is wrong, I would guess it is more likely about 20%.
The Orbital plane of a Gas Giant would almost certainly be different to that of it's Moons, but for the bigger moons they would be closer in and would have a smaller angle difference to the solar plan then small moons. there for I would expect to see eclipses from the surface.
Also Orbits around a Gas Giant would be more likely to last between 2-20 days (based on Jupiters moons: Io=42.5 Hours / Callisto=16.7 Days) Life on a Moon would be very difficult as unless there is volcanic activity there will be no surface heat for hours to days at regular periods.
Tidal lock would is very likely but I would never have though of that.
All in all, for the sake of the story, I'm going to ignore these errors.
The internal heat generated by tidal forces would, by necessity, also be accompanied by seismic activity. Fortunately it would be limited and predictable.
Something that might make a difference is that with a 'warm' object taking up much of the sky, the moon won't be able to radiate as much heat as a planet. Combine it with some cloud cover and place the planet closer to the sun, and it might have rather interesting weather.
Hamsterman
Generally speaking we expect Gas Giants far enough away from a star that any moon in direct sun light can expect very little heat in its rays. What you can expect is radiation.
Really the moons of a Gas Giant are not places we can expect to live comfortably outdoors.
That said, who really knows! and this is a story not reality so it's just added flavor.
I think it was Jupiter that had some of its bigger moons within its own magnetosphere, so the moon is protected by its planet against radiation/cosmic rays. *checks* Okay, in case of Jupiter, all of the big moons (and then some) are within Jupiter's magnetosphere.
Of course, this still leaves ultraviolet rays or x-rays.
I'm sorry, Melanie, but you cannot say that I'm dead wrong. You are basing your perceptions on a single known system... our own. Now that we are discovering planets all over the place, the one rule we are finding is that there are no rules. You can have a gas giant in close to a star, you can have it far away. You can have a pair of Earth-like worlds orbiting a common center of gravity between them. You can have an Earth-like moon tidally locked to a gas giant, or not tidally locked. You can have it with a long orbit and a short rotation, or vice versa. Unfortunately, we don't have the capability of detecting moons orbiting extrasolar worlds, but if we did, I'm pretty sure that you'd find those moons violating everything we currently believe moons can be and do.
Comparing the orbit of our moon to that of, say, Haven, doesn't work. Of course the lunar eclipse only lasts hours. The moon is a hell of a lot smaller than a gas giant. (Our moon has a radius of 1079 miles, and Jupiter is 43,447!!) Different sizes, different orbital altitudes, different orbital planes, different distances from the parent star, etc... The only 'Lunar' orbit there is is the orbit of our moon around Earth. (That is the only moon named 'Luna'.) Titan's orbit around Jupiter is not called a 'lunar' orbit, as that moon is not named 'Luna'. (Same thing as the Tau Ceti system is not called a 'Solar system', as the star's name is Tau Ceti, not Sol.)
The point is, anything goes. It makes sense that if Haven took, say, 100 days to complete a single orbit around its parent (the gas giant), and it's orbital plane is pretty much along the same plane as the parent planet's orbital plane around the parent star, then it would in fact spend half it's year in darkness. (Approximately speaking of course.) Of course, if its orbit was NOT along the same plane as the parent planet's orbit around the parent star, then it's a different story. Also, if you are on the dark side of the gas giant, it isn't going to be reflecting any of the parent star's light, so It's not going to be lighting up that moon.
If you start plugging different variables such as size, mass, orbital speed, rotational speed, etcetera into simulators you can get all kinds of crazy day/night patterns, some of them unbelievably insane.
We know almost nothing about what can and cannot exist as far as planets, moons, stars, orbits, methods of formation, etcetera. And the more we learn, the more we realize that our understandings are flawed.
I still think that a moon being in the shadow of and being behind a parent planet are two separate things.
Simple test.
Put three tennis balls down in a line. 1) Sun. 2)Planet. 3)Moon.
And now move the moon around the planet.
For a very small portion of the rotation the planet is between the sun and moon. That is the "shadow" and the period of darkness.
(Yes the Gas Giant is bigger then the Moon but the Sun is bigger then the Gas Giant and this is just an example.)
All in all, it doesn't matter and I'm happy to ignore it.
Haven't checked this thread in ages. Anyhow...
I’m sorry, Melanie, but you cannot say that I’m dead wrong. You are basing your perceptions on a single known system… our own.
Not exactly. I was basing this on known physics in general and optics in particular. I was only citing our system as an example to illustrate the points I made.
The long darkness of Haven would mean that half of its orbit is in the shadow of its mother planet. Which is physically impossible - literally. Unless your system looks like this:
However, the "gas giant" would have to be a half orb that's bigger than the star it orbits. Which, in itself, is physically impossible. The "moon", on the other hand, would have to orbit both the planet and the star - in which case the term "moon" doesn't really apply.
Sorry, I forgot that tags work differently here than on any other forum I know. For easy reference, this should now finally be the pic I doodled up. Hopefully.
I'm finding it impossible to make any sense of your image, as it appears to have a moon and a star, and no gas giant. But that doesn't matter.
I believe that the reason you are finding this impossible to believe is that again you are basing your argument on assumptions about the gas giants distance from the star, the type of star, the size of the gas giant, the speed of the gas giant's orbit around its parent star, etc...all using values similar to those seen in our system.
If the gas giant is sufficiently sized, relatively close to its parent star, the parent star is small (in comparison to Sol) and the gas giant travels rather quickly around its parent star, then all you need is the correct speed of the moon around the gas giant to get the 58 day dark/light cycle. You would also need the moon and the gas giant to both be orbiting in the same direction around their parents, or things get all out of whack.
Would the values be something believable based on what we have observed in our tiny peek at the universe thus far? Probably not. But many of our assumptions about what could or could not exist in a system have been proven wrong.
I also have to point out that the argument itself is rather pointless. We are talking about a work of fiction that uses a "jump drive" that has no basis in any scientific theories that currently exist. This reminds me of the argument I always have with my science guy about the speed of light. He says that the math doesn't lie, that you cannot exceed the speed of light. I say, that until someone tries and finds it to be impossible, it is still possible. We once thought that exceeding the speed of sound would not be survivable, until we did so and found out we were wrong.
Remember, it is Science Fiction, not Science Fact.
It's not a matter of using one system or another, it's a matter of sheer physics.
Since you claim that Haven has a cycle where 50% of its time is spent in the shadow of its mother planet - which is a gas giant - show me how this could work. How can half the moon's orbit be in the shadow of its parent planet?
Frankly, it can't be - unless
a) the gas giant is bigger than the star, which in itself is highly unlikely
b) the distance between the star and the gas giant is very low - actually, the distance between the center of the star and the center of the gas giant needs to be less than the size of the gas giant. This leads to the next point.
c) The gas giant would have to be a bowl-shaped something wrapped halfway around the central star, which leads to
d) a lunar orbit that goes around both the planet and the star.
As you may have guessed by now, the bowl-shaped reddish smudge in my drawing is the gas giant in this example.
The only other way this could work is if there was something like negative gravity, the gas giant possesses an amount of negative gravity that (almost?) equals the positive gravity of a black hole and bends the light outwards. Which is equally ludicrous for an object of planetary mass.
Our Moon is in a tidally locked position so it receives exactly the same amount of sunlight on all sides except for the portion that faces the earth which would technically be the dark side of the moon because if you were to stand there the sun would never be visible directly overhead because the Earth will get in the way. You would get a Morning (~6 earth days long) and an Evening (~6 Earth days long) but Noon would have you in darkness (~2 earth days long) not to mention the half orbit where that side of the moon would be facing away from the sun or experiencing a local night time (~14 earth days)
https://www.quora.com/How-long-does-each-phase-of-the-moon-last :The total cycle of the moon lasts almost a month (29.5days); there are 8 phases, so it is simple each phase lasts 29.5/8=3.69 days, a little more than 3 days and a half.
If Haven was tidally locked then it would always face the Gas Giant, and receive Reflected light from its parent for very roughly 7/8's of its orbit and a city facing the Giant would only receive light from the star for about half of its orbit due to the angle of the moon's body to the star. Haven does have a day night cycle though which means its rotating on its axis - so it will get star light for the same period as it would get reflected light - 7/8's (ish) of its orbit (this means that only 14 / 116 days would be spend in complete darkness not 58 / 116)
The Teacup shaped Gas Giant orbiting a star is a pretty fiction. A gas giant will always be spherical because of the extreme gravity an object that size has. Even were that teacup make of solid Steel it would have a mass so large that it would fold in on itself and crush itself into a roughly spherical object larger in size to its parent star. its gravity would actually be greater the the star and the star would be orbiting it for the time it takes from blinking this system into existence and it collapsing in on itself in a matter of days (space is still a big place to move that much mass that far) it would be lucky not to have a nova scale event there and then. There is a reason Dyson Spheres are spoken of as the pinnacle of Development in pretty much all sci-fi that mentions them.
The only way I see it making sense is if Haven was on a oblong orbit that was close in to the gas giant on the sunward side and wide out on the outer system side - if this were the case then the near orbit of the moon to the super giant Haven orbits would result in a lot of gravitational forces which would make the rock uninhabitable... so it really doesnt make sense for the Moon to be in the shadow of the gas giant for half of its orbit.
It would be interesting to see a case where it was possible to have a moon in darkness for 50% of its orbit of a gas giant and yet still be habitable but I cannot for the life of me understand how it could happen.
The Teacup shaped Gas Giant orbiting a star is a pretty fiction. A gas giant will always be spherical because of the extreme gravity an object that size has.
I thought that was common knowledge and thus didn't even argue that point. 😀 I mean, seriously, that's exactly why this hypothetical system is physically impossible.
I dont remember that it was said that the only planet in the system was the gas giant, or that the only moon was Haven, there were quite a few remarks about the density of the ring system, so there are quite a few reasons that the light could be obscured for half a local year. And trying to apply physics is a good start but where you are failing to make the jump is that you dont know the infinite variation of orbital mechanics given infinite combinations in the system makeup. Quite frankly what Ryk said still holds true, the one thing we learned about the universe from our observations is that nothing seems to be set as fact as far as planetary positions are concerned. We simply dont know enough to say it is impossible for a moon circling a gas giant in the P. cluster to have a night that is 58 days long. If Alaska can have a night 67 days long its not to far a jump to assume that given the right circumstances and system makeup Havens night can be 58 days long...
For Haven to move the way Ryk said - half of the Planetary orbit in the shadow of the Gas Giant - the Haven's Orbit would need to be so warped - either being very oblong or being effected by different gravity wells that were not mentioned in the story - which they should have been.
A Moon with a non circular orbit or a moon with an orbital speed differential as large as we are talking about would be talked about. Scott is a pilot, he would notice these things - know that they matter. Anything that could effect the orbit of a moon would effect the ship.
