A Whole Lot of Class M...

[C5]

The counter-planet offers indeed great possibilities, especially in the Verne or Wells setting Dan envisions.
I would very well see a clever scientist as you meet in this sort of setting inventing a crude space travel machine in order to prove his theories of a mirror world (no, not that one ), wich he could have established thanks to some the reflection of the sun's light in the other planet's atmosphere seen on another planet in the system (don't ask - I'm not sure even I understand what I'm saying )

The twin planet fits as well in that setting; visual evidence of life on the other planet could have been established for a long time, and even some crude ways of communicating could have been tested before the invention of radio (say, some titaneous work designed to build monuments large enough to be seen from the other planet)...

Hey, but these are cool ideas!! I think I'll have to steal them for my following adventures!!

[Phantom]

Question, do they have to be strictly Class M worlds? Or just have the ability to support mammalian life?

If the latter is true then consider:

L Class: These planets are fairly common; they have oxygen-argon atmospheres and liquid water. Humans can live on them quite comfortably (may need regular Triox treatments). Class L worlds have only plant life. Usually show signs of ancient terraforming.

-from TOS and TNG.

A possible, Trek, answer for your probalem

[tonyg]

Generally the lifezone (or biosphere) on a star is based on how much energy it puts out, normnally refered to as it's luminosity. Sol (our star) is a 1. This is the distance that liquid water could exist. A star with a 10 Luminosity would be ten times as bright as sol. The energy that a planet gets is tied to the the luminosity and it's distance from the star.

THis means that you can calculate the life zone of a star by taking the square root of its luminosity. For eaxample for SOL the lizezone is 1, meanining that a planet 1 AU (93 million miles) away would recieve the same energy as Earth.

You can determine the energy recieved by a planet (relative to Earth) as LUM/(DISTANCE^2). Thus a planet that is half the ditance from the star recieves [I} four [/I]times the energy.


Since, a brighter, hotter star has a larger bisophere, it could have more chance of planets in this life zone. This might be something that an highly advanced culture might try to take advange of by "moving" a planet to a "better neighborhood". Niven's Ringworld and Dysn's Sphere are the extreme example of this idea.



This can be helpful if the narroator wants to detail a starsystem for his campaign. Especially for a major locale, or for some sort of abnormality that the PCs can study. This could be things like a Class M plaet that is woutside the biozone.

Heck, any star with several Class M planets would be quite the find, and a valuable resource.

[tonyg]

There was a movie called DOPPLEGANGER that did use the idea of mutiple worlds in our Solar System.

[Diamond]

For a 19th century-ish steampunk civilization, there's one clear way for them to detect a planet on the other side of the sun in the same orbit. They can't observe it directly, sun is in the way. Observing it from light reflected off of it, onto another planet, and back to the homeworld is ridiculously unlikely. But there is a simple, clear way that classically fits 19th century tecnological capability: by indirectly observing that planet's gravitational pull on other bodies.

For example, if a comet passes behind the sun, and reapears on the other side with it's orbit changed, this would be clear and unmistakable evidence of the counter-planet. It would be easily within 19-century Earth astronomers ability to figuire that out. From there, some Steampunk advances and you've got a great story.

Note that there are some interesting consequences to this discovery, even before that civilization can interact with the other planet. For example, their theories of planetary formation are likely to be thrown into terrible confusion - just the existence of the counter-planet would seem to go against natural planetary formation processes. This might make the scientists confused and cause an increasing of Religeon's importance. Or possibly the native civilization realizes there's powerful aliens out there... with all the corrsponding interesting social consequences that has.

[C5]

Originally posted by Diamond
Observing it from light reflected off of it, onto another planet, and back to the homeworld is ridiculously unlikely. But there is a simple, clear way that classically fits 19th century tecnological capability: by indirectly observing that planet's gravitational pull on other bodies.

My bad
Why did I discard the gravitational proof when I imaginated this reflection thing? Oh well... the physics courses must be too far away...

Another way to have many planet being approximatively at the same distance of the sun would be to use the Pluto example again : sometimes, Pluto crosses Neptun's orbit and ends being nearer from the sun than Neptun.
Likewise, you could imagine two planets, being at the "correct" distance from their sun, but not having exactly the same orbit (like the same ellipse, but with the sun being not at the same center for both of them). That way, you can have two planets being almost on the same orbit, but with a more natural cause (hey, it happens in our system... wich is natural, right ? Right?? ).
However, the "unseen world" plot device falls, as the two planets would certainly not be always on opposite side of the sun and thus be visible from one another.

[First of Two]

SF scenarios I remember:

Two planets revolving around a common center of mass is workable. Pluto and Charon do, (and so do Earth and the Moon, to a lesser extent.) You might end up with a "Rocheworld" (series of 5 books by Robert Forward), but not necessarily.

Planets sharing each other's "Trojan Points" There exist points in each planet's orbits into which objects can be dropped and have their orbits remain stable. Jupiter has these points 60 degrees in front of and behind it in its orbit, and there is a cluster of asteroids in each space. I suppose it's possible to put a planet there (but it would have had to have been moved there by someone)... by extension, it might be possible to have a 'ring' of 6 planets, each 60 degrees in front of the other, around a central star. (I think Larry Niven had the Puppeteer race doing something similar)

If the system has a broad 'life zone', it could have 2 or 3 class M's in there.
If the system has a somewhat bigger Jovian planet than Jupiter is, and the bigger Jovian has bigger moons, then some of them could be class M.
If a Jovian orbits within the 'life zone,' any moons it has big enough to hold an atmosphere could be class M.
If a multiple (binary, trinary) star system, then if the stars are far enough apart, each of them could have their own 'life zones.'
If you combine these possibilities, you MIGHT be able to hold a whole mess of class M's in a system.

[tonyg]

On a real world note, some of the outer planets in the solar system were discoered becuase of ther effects on other obejct in the solar system. In fact, some believe that there are still planets in the solar system waiting to be discovered.

[Phade]

Originally posted by Dan Gurden
OK, heres another question for you amateur astrologers out there.

Is Class M as a planetary class a real designation or a Star Trek invention?

I ask because in 'Strange New World', T'Pol describes the nearby planet as M'Mshara class, in what sounded like a Vulcan designation... Which if connected to the Starfleet classifications doesn't explain why they run in Terran (English) Alphabetical order...

Which sparks up another thread...

With my limited knowledge in astronomy and such, as far as I am aware the classification of planets, such as Class M, is purely a Trek invention. Though IMHO it is a pretty worthy system, and makes it easy for the layman to understand the different types of planetary bodies. As a side note: Class J planets are gas giants (we all know that ), as from what I can tell this stand for Jovian, in reference to Jupiter. So the reference of T'Pol in the episode, calling it a M'Mshara class would somewhat explain where we get Class M from. Though is mostly speculation on my part, but seems to make sense, at least to my sensibilities.

Safe journeys,
Lt. Cmdr Phade
=/\=

[tonyg]

I don't believe that there is any sort of "offical" planetary classifcation system yet. Us pre-warpers don't have a reason for it. Who knows, if we do develope FLT travel we might wind up swiping the one from TREK.

[Bill Harris]

Originally posted by Sho-sa Kurita
But how about planets in basically identical orbits, but on opposite sides of their star? This would turn the previously discussed 3-planet sytem (Venus, Earth, Mars) into a six planet system. This would even be more likely than the other scenario (albeit neither is terribly probable).

This would only work if there were just two planets in the system. More than that and the orbital perturbations really mess things up. The two planets would no longer be on opposite sides of the star and would eventually either collide or ejecting one or both out of the system.

[tonyg]

Bill,

Yeah, you're right, although depending on the orbial radius and age of the system it might take some time for that to occur. With a very bright star the biozone would be much larger, and the planets could take a very long time to circle thier star and gain on each other.

Graviatorinal effects are also one of the reasons why most astonomers don't believe that Binary and Trinary star systems could have Earth-line (Class M) planets.

[Bill Harris]

It wouldn't take as long as you might think. It would only take a few hundred years/thousands of years to destablize the system, assuming there is a Jupiter type planet in the system. More likely on the order of millions of years if there are only terrestial planets.

Which, on the astronomical scale, is nothing.

[Timothy]

This might just be ignorance speaking but could you not just say this is the way it is and not have to have a scientific explanation for it? I mean nearly all TREKnology is based on our theories anyways and not all fact. Plus you are the GM and it is (for all intents and puposes) your universe....


If I understood what you are doing in your game the idea is to focus more on the civilizations that are there already and not HOW the planets got the way they are.....Who knows the players may follow the wrong 'red herring" anyways so you will never have to explain why the planets are the way they are....

[TomMarg]

I would agree with tim ( welcome aboard btw ), ultimately it's how you want your system made up. If your players are the type that want to pick apart the 'reality' of this being possible , let them tear their hair out trying to figuire it out....after all the universe is a mysterious place, and not everything can be easily explained.

I personally found that if you want a detailed system set up use the system generator in gurps space suppliment. It's the best resource I've ever come across with all planetoid bodies down to the decimal point in A.U.'s from the sun. (calculator req. ).

It also discusses at some length, bodes law and bio zones of habitation for each star type.

If you don't have this book, I would strongly urge you ( don ) or anyone else to get this book.