Space Voyage #1 Chatter

[Jay-qu]

Unless its not a brown dwarf.. I dont think so.. BD's are failed stars, not burning H, they are hot because of the gravity compressing the gasses, and as pointed out slowly cool down via interations that let off primarily IR radiation. If anyone sees a way to get around this half convincingly, feel free, it is science fiction after all :)

[Janus]

I just thought of another aspect of a world revolving a BD. You wouldn't be able to rely on the Greenhouse effect to give your surface temp a boost. There wouldn't be enough visible light to cause heating of the surface that is then trapped by the atmosphere. In fact, there would be very little surface heating at all. Since most of the energy given off by the BD is in the infrared, the vast majority of the planet's warming would come directly from the atmosphere absorbing the IR. This also means you won't get the uneven surface heating that causes many of the rising and dropping air columns that generates some of our weather.

[TheFaithfulStone]

Okay, the last ten or fifteen posts (including some of mine) have been totally off the rails.

 

Our science is getting sloppy, and our plot is getting just weird.

 

TFS

[Pyrotex]

...totally off the rails. ..,and our plot is getting just weird.

Okay, you do have a point. After all, Geek Boys just wanna have fun. But now the mystery of the nanobots is solved once and for all, Tormod is officially onboard whether he likes it or not, and we can facetiously include him in all future science and plot turns whether he likes it or not. ;)

So, I'm with you, TFS!!! Let's suit up, grab a bag of ice pitons, a coupla rocket backpacks, and touch ground on Enceladus!!!

Hi ho!!!

[Pyrotex]

Let's examine that....If we assume that it happens 10 times faster, this means that it wold take about 1.25 billion years for the moon to go from its furthestmost orbital distance to inside the Roche limit where it would break up into a ring....The tide would have top go from low to high in 22.5 hrs, meaning it would have to travel at about 2 km per hr.

This is a slow waliking speed. This would also mean that a "oceanview" would actually only be able to see the ocean for a small fraction of every day....

This is looking good. What if you're right and moon is just NOW reaching the Roche limit. We might be able to get there just as the first major cracks appear in the moon! Some terrific science there, I'll bet.

Meanwhile, your "oceanview" might actually be at the edge of a deep "grand canyon several kilometers deep. Every 22.5 hours, the water would rise up to the edge of the canyon, then fall back down leaving a slightly damp river bed at the bottom. If 2.25 kilometers deep, then the tides would rise (and fall) at a rate of 200 meters per hour or 3.33 meters per minute.

[Janus]

This is looking good. What if you're right and moon is just NOW reaching the Roche limit. We might be able to get there just as the first major cracks appear in the moon! Some terrific science there, I'll bet.

Here's the thing, if we assume that our moon is of the same density as the Earth and our planet the same as Jupiter, then it is very likely that the Roche limit for the moon actually lies below the "surface" of the Planet. This is because the actual Roche limit depends on the relative densities of the two bodies, and the Earth is much denser than Jupiter.

In any case, there are two Roche limits we need to consider. Fluid objects (such as the oceans and atmosphere) have a much further Roche limit than more rigid bodies (such as the moon itself). As result, the moon will be stripped of its water an atmosphere long before it gets close enough for the moon proper to break up. So maybe its that the moon is just starting to lose its air and water.

 

 

Meanwhile, your "oceanview" might actually be at the edge of a deep "grand canyon several kilometers deep. Every 22.5 hours, the water would rise up to the edge of the canyon, then fall back down leaving a slightly damp river bed at the bottom. If 2.25 kilometers deep, then the tides would rise (and fall) at a rate of 200 meters per hour or 3.33 meters per minute.

 

I did some numbers as to what kinds of tides we might see. With our largest possible orbit for the moon, the tidal bulge caused by the planet would be 4.876 km high. The tidal bulge caused by the BD would be 247m high.

(compared to the .6m tidal bulge caused by our moon.)

 

Now here's where it get interesting. Normally, you would just add and subtract the BD tidal bulge from the Planet tidal bulge and get a tidal bulge that varies from 4.629 km to 5.123 km (like you do with the Sun and Moon to get Spring and Neap tides. )

 

But there is a complication here. The BD produces a tide accross the orbit of the Moon itself with "stretches" the orbit of the moon, causing it to be further from the planet when the three bodies are in line than it average orbital distance. (the Sun does the same thing to our Moon, but due to the much larger difference between the radius of the moon orbit compared to the distance to the Sun, the effect is not too pronounced. )

 

In this new case however it is enough to create a "orbital tidal bulge" of 60750 km. Meaning the moon is that much further away from the planet when they line up with the BD. This extra distance is enough to reduce the size of the tidal bulge from the planet by 1225.134 km. So now our planetary tidal bulge varies from 4.629 km to 3.651 km.

 

We still need to factor in the BD tidal bulge, but note that now it acts in opposition to the Planetary bulge. When the bodies line up, the planetary bulge is smallest, and the BD bulge adds to it. Conversely, when the bodies are at right angles, the planetary bulge is highest and the BD bulge subtracts from it.

 

The upshot is that the tides change by 731m every half day, with high tide occuring at sunset and sunrise, and low tide occuring at noon and midnight.

 

This is for an orbit with a period of 72 hrs (three Earth days)

 

If we half the orbital distance, we get a day of 25 hrs, but now our planetary tidal bulge swells out to a height of over 39 km! Our tidal variation however, only increases to 951m.

[Pyrotex]

Here's the thing, if we assume that our moon is of the same density as the Earth and our planet the same as Jupiter, then it is very likely that the Roche limit for the moon actually lies below the "surface" of the Planet....I did some numbers as to what kinds of tides we might see.....

Awesome. Both my hats are off to you. :phones:

[TheBigDog]

Janus, I would be happy to understand what you are explaining, much less have to do the math and explain it.

 

TBD + Orbital Physics = :xx:

Janus + Orbital Physics = :D

 

TBD + Pyrotex = Janus + :beer: + :beer: + :beer: + :beer: + ;) + :beer:

TBD + Janus = Pyrotex + :beer: + :beer: + :beer: + :beer: + :beer:

 

:phones: You do the math. :doh:

 

Great work guys!

 

I am going to put on my ever growing list of intentions to take excerps from your posts here and weave them into the story. Probably as dialoge of you explaining to me the physics involved with what we have found. And while I am at it I may raise some new questions for us to investigate and discuss.

 

Bill

[Janus]

Here's a map that shows how the Planet might look like. This just meant to show ocean/landmass relationships and is not meant to be color-correct (things would look quite different under the light of the Brown Dwarf.)

 

Because of the large tidal bulges casued by the larger planet, you will not that there would be two large oceans and the vast majority of the land would exist in a band circling the planet:

 

 

As netined before, outr planet will slowly circle in closer to the larger planet over time, as it does so, more of the oceans will shift to the planetary tidal bulges.

this is what the same planet would look like after it has moved further in.

 

Note that some originally dry land is swallowed by the growing tidal bulges and new land will be exposed in the band. Leaving us with two completely separated oceans and one planet girdling continent.

[Jay-qu]

and how the hell did you do that :)

[TheFaithfulStone]

That's awesome as always Janus.

 

TFS

[Pyrotex]

... Leaving us with two completely separated oceans and one planet girdling continent.

Entirely adequate, Janus! Woot! Woot!

 

Am I wrong in assuming that one ocean will be centered facing towards the gas giant, and the other ocean facing away? So, the gas giant will always appear, from the circling continent, to be on or near the horizon. In fact, ignoring orbital wobble for a moment, the gas giant will always appear (more or less) at the same point on the horizon and at the same inclination.

 

The north and south poles of our moon would be located upon the girdle continent. So if you were performing a pedestrian circumnavigation (walking around the girdle continent) you would encounter two zones of "tropics" and two zones of "arctic".

 

This leads to the awesome possibility that those two tropic zones are ecologically isolated, and therefore have evolved different ecosystems and different species. Likewise the two oceans may have totally different life forms!!!!

 

Perhaps, WILDLY different!!!! :hihi:

[TheFaithfulStone]

This sounds much more interesting than a bunch of nanobots.

 

TFS

[Janus]

and how the hell did you do that :singer:

 

Starting in POV-Ray, you create an iso-surface object located at the origin, this is an object who's surface is defined by a mathematical function. Start with the function for a sphere. You now modify this function with a function defined from a pigment pattern (Bozo, with some turbulence). by scaling this function properly you get your basic continents. Now further modify the function with a second pigment pattern function (this time Wrinkles) scaled down even further. This futher refines your continents with greater detail.

 

This gives you a sphere with a truely uneven surface.

 

Assign a an Onion pigment pattern to your iso-object so that different "altitudes" on your planet vary in color. This gives your continents their shading.

 

Now create a sphere also located at the origin and pigment it blue. The base size of the sphere should be such that its surface is at what would be considered at "mean sea-level". Any part of the surface of the iso-object which protrudes above the surface of the sphere are your land masses.

 

You can now scale the sphere so that it follows the contour of any size tidal bulge you wish, thus exposing more dry land in some places while "flooding" others.

[Janus]

Entirely adequate, Janus! Woot! Woot!

 

Am I wrong in assuming that one ocean will be centered facing towards the gas giant, and the other ocean facing away? So, the gas giant will always appear, from the circling continent, to be on or near the horizon. In fact, ignoring orbital wobble for a moment, the gas giant will always appear (more or less) at the same point on the horizon and at the same inclination.

 

You assume correctly.

 

The north and south poles of our moon would be located upon the girdle continent. So if you were performing a pedestrian circumnavigation (walking around the girdle continent) you would encounter two zones of "tropics" and two zones of "arctic".

 

This leads to the awesome possibility that those two tropic zones are ecologically isolated, and therefore have evolved different ecosystems and different species. Likewise the two oceans may have totally different life forms!!!!

 

A couple of points. Because of the large tidal effect of the BD, our planet will likely orbit in the same plane as the larger planet orbits around the BD. With it being tidally locked to the larger planet, this means that its poles will not be tilted to its orbit. This means that it will not have any true artic or tropic zones as these areas are defined by the axial tilt of the planet.

 

Also, due to the fact that the majority of the planet's warming coming from direct atmospheric heating, we might not see as much temperature variation due to lattitude. We might not get ice caps as such.

 

Perhaps, WILDLY different!!!! :singer:

[Jay-qu]

So whats going on fella's?

 

I think we owe it to the story to at least go out with a bang!

[Mercedes Benzene]

I was hoping someone would try to bring this story ba

I think we owe it to the story to at least go out with a bang!

Aww I really hope it doesn't have to end here. :(