> At 07:46 PM 10/3/99 -0400, you wrote:
I vote A, since the recent finding of humongous (larger than Jupiter) planets
very near to their star (as in clser than the earth and even mercury as
compared to our system) in some of the nearby star systems has thrown a number
of theories about jovian formation out the door. I think that Popular Science
just had an article about some of them, there was something on their website
but it didn't get into specifics, I thnk it was the September issue.
Later,
I'm about to make a series of system maps (using Schoon's
scale of 1 hex = 1/3 AU or 50 million km) for the inner
systems for several stars. If I can get Angelfire to behave tonight, I'll post
the first one (Sol system) on or about
www.angelfire.com/va/laserlight/fullthrust.html ; it will be
followed by other strategically important systems like Alarish, New Zimbabwe,
and New Persia (but not uninteresting
and out-of-the-way places like Albion or Nova Moskva--if you
think it's important, you make the map).
Now, as I generate planets, I can either place their orbital distances
randomly to suit myself, or I can generate them in accordance with whatever
theory seems best at the moment. For Alarish, I put the brown dwarf at the
distance to get the same insolation as Jupiter, on the theory that the local
temperature was favorable for condensing a large planet there. Pure
speculation on my part.
So, you astronomer blokes, once again we're going to call on your erudition:
a) place orbits randomly? b) place major gas giant at Jovian insolation
distance? c) other?
--Chris DeBoe
Quixtar IBO#706882
http://www.quixtar.com
> At 7:46 PM -0400 10/3/99, Laserlight wrote:
I'd say randomly within a reasonable range, although I bear very little
resemblance to an astronomer.
And angelfire.com is running, albeit very slowly; a tracert shows slow traffic
on both my ISP and alter.net (which seems to be angelfire's upstream
provider).
I'll take a look at my Jovian maps again, I've got a 3D model, and was just
about to set up a display showing Phil's sensor ranges. I'll see what happens
and post it to ImpDisp.
I'm talking to myself again....
> At 7:46 PM -0400 10/3/99, Laserlight wrote:
BTW using hexes 0.5cm across and this scale, I can fit about 6AU across on the
map. If anyone wants to go conquer
Saturn, you'll have to generate another map--one with lots
of blank space. I withdraw my suggestion that we drop the Jump Limit way out
there; instead let's go with David Weber's canon 22 light minutes for a G0
star, which works
out to something like 2.75 AU--watch out for asteroids as
you jump, though.
> If I can get Angelfire to behave
Not yet
> I'll post the first one (Sol system) on or about
> Laserlight wrote:
> I'm about to make a series of system maps (using Schoon's
Not an astronomer, but an interested party...
Ever heard of "Bode's Law"? He was an astronomer who suggested that the size
of the planetary orbits follow a numerical sequence. There is more at this
site. This works for all of the planets except Neptune and Pluto. (Astronomers
are still arguing over that one. Some have suggested that Bode's Law applies
to all star systems...)
I've just looked over Phil's EW rules. Here's a first approximation:
target: completely passive (coming in on a hyperbolic, running
silent, no stealth), mass 26-50 (big enough to be dangerous) and
Superior military sensors. I'm interested in the maximum range at which it's
possible to get a loose LOB or a bogie marker. Maximum
roll of 6, +4 for the sensors. +1 for mass of target gives an 11.
That allows for -8 worth of range modifiers or 96".
That's a little close... I suspect the range bands should be doubling in each
increment, not increasing linearly. That'd make the range 12 * 2e8 or 3072"
That's a bit much, although the worst case (farthest a roll of 1 would detect
our target above) detection would be our old friend 96"
Now if we roll only when the conditions change instead of every turn, the hunt
take s a little longer, but may be more interesting (it also
has the potential to become a long drawn out two-person shadowboxing
match).
If the range bands for detection are doubling, then the various levels of
detection aren't too close to each other either. Still, I'm going to take
another look at some variant Traveller sensor systems I have lying around here
somewhere. I do admire Phil's rules for fitting on two pages. I'll try for
that too (another person who thinks he has too much free time).
Of course, straight FT sometimes looks like distance in inches is really a
logorithmic scale. Note how the various Honor Harrington conversions
dramatically compress the differences between missile range (10e6 km or 10e7
km) and energy weapon range (10e5 km). It's a little odd, but it still plays
well so I certainly won't complain. Upping missile endurance (20?) would help,
but would reduce the facility of tabletop play something awful.
I'm going to do a new version of my Jovian diagram with a 96" and 384" ( a
nice, midgrange detection result from Phil's rules)
That'll go up on the ImpDisp website listed below.
> At 11:46 PM -0400 10/3/99, Donald Hosford wrote:
> At 11:46 PM -0400 10/3/99, Donald Hosford wrote:
I've been looking for that! I mentioned Bode's Law a few weeks ago and I wish
I'd had the URL. I hadn't seen it deconstructed like that. The relationships
to Mercoury's orbit are very interesting. From that it looks like we can just
randomize the first orbit (based on stellar mass) and then calculate the
orbits from there on out. Heck, Traveller Book 6 just assumed Bode's Law holds
and left it at that. Then we just populate the orbitals; Traveller Book 6
comes to mind again... There's a lot of valid criticism of Traveller, but its
method of generating star systems is just plain useful (time to go work on the
Pocket Empires DB again...)
[quoted original message omitted]
I vote for C which is a combination of A and B...
Bodes law doesn't work. It doesn't work for the planetary moon systems
(Jupiter, Saturn, Uranus and Neptune), it doesn't work for the any other star
system we have information on (the pulsar system that it did fit recently had
its planets replaced with perodic solar activity by our system), and it may
not even work for our sol system... Why? Some astronomers have started to
piece together the orbits of a bunch of asteroids between Earth and Mars and
are speculating that this could be another asteroid belt...
I would argue that the best way to do it is to place them where you want as
long as they are not too close to each other or the star(s) to disrupt them...
I don't remeber the formula but will look it up and post it when I have time.
> Laserlight wrote:
I don't know if this will appeal to you, but you can go to
http://www.geocities.com/Area51/6902/w_accr.html
> Laserlight wrote:
> -----Original Message-----
I agree.
Bode's Law is the only one I had heard of BTI (Before The Internet). Say,
maybe we could assemble a random table that would randomly choose which method
to generate the system with, and more random tables for
each method. That should suffecently randomize the star systems. :-)
So, are there any professional or amature astronomers out there?
Somewhere out there is a program called Accrete. It generate complete systems.
If someone could point out where it is on the web please do. I've got a copy
of it if all else fails.
Not sure exactly what model it uses but it comes up with some pretty
neat systems. If you'd like a copy just e-mail me.
> So, are there any professional or amature astronomers out
Indy said:
> Yeah, but just been too damned busy to spare any time to
> At 10:54 PM 10/3/99 -0700, Michael wrote:
[schnip]
> I've been looking for that ! I mentioned Bode's Law a few weeks ago
This got me to pull out the 2300AD rulebook and flip to the back... yup, the
world generation section sounds a like like this. You randomly generate the
radius of the first orbit, then the multiplier between orbits... not sure how
they'd generate Sol out of that, since (as the web page above shows) Neptune
falls halfway between Uranus and Pluto. Oh,
well, that's what a GM is for.... ^_-
> So, are there any professional or amature astronomers out there?
Yeah, but just been too damned busy to spare any time to look some
stuff up for laserlight. :-( I'd consult with a colleague of mine
at work who is very much into searching for planets/brown dwarfs
around nearby stars, but he's out on sick leave, having suffered a heart
attack a week ago. When he's better I'll bug him.
Anyway, the website I maintain on unseen companions around 'nearby'
stars ('nearby' being relative ;-) is sorely sorely sorely out of
date and in need of upgrading, so I won't point you in that direction
right now. If/when I get a chance to update it, I'll let ya know.
Mk
> At 10:20 PM 10/4/99 -0400, you wrote:
The Accrete home page is at:
http://www.accesscom.com/~iburrell/create/accrete.html
Nyrath the nearly wise and completely indespensable has links to this and a
bunch of other solar system mapping programs at:
http://www.clark.net/pub/nyrath/smap07.html
Scientists who work on planetary formation theory consider Bode's Law as an
interesting mathematical idea that doesn't explain reality, but rather happens
to coincides with it in our star system. Even if they are wrong, Bode's Law
doesn't work for our purposes because you have to deal with captured
satellites, planets and moons shifting their orbits, etc. The root of our
problem is not just how star system form, it is also how they evolve over
time. I have been trying to develop a star system formation and evolution
system that emulates reality for years. I am no closer now then when I
started, but I did learn how little I really know.
> At 6:42 AM -0400 10/5/99, Imre A. Szabo wrote:
http://www.geocities.com/Area51/6902/w_accr.html is a very nice solar
system generator. I just wish it produced a text listing of the bodies in the
system instead of just pretty pictures; but that's what source code is for.
M-x lurk-mode-off
Someone asked if there are any astronomers out there, well, I claim to be one
on my CV. Note, I know jack about planets, I am
extra-galactic
observer.
If you wanna make solar systems, do whatever you want, the current theory is
pretty up in the air. A lot of the physics of accretion is not well understood
(people still argue about what causes the all important vicosity) so why a
planet ends up as big as it is and how far from the star it is, nobody can
answer definitively. So do whatever you want.
I checked out accrete, the java version looks really cool. However, where the
planets start is random, there is no physics in it.
If you want to check out planet search stuff, check out:
http://cannon.sfsu.edu/~gmarcy/planetsearch/planetsearch.html
He has a table candidates, that could give you ideas on where to put your
jovians. However, that survey is chocked full of selection biases (just like
everything else in astronomy). If you check his table of planets, you will see
that he finds planets on circular orbits near the star and on highly
ellipitical orbits far from the star. This is because a planet far from the
star with a circular orbit will have a much smaller effect on the central
star, making it much harder to measure the planets orbital parameters.
well, back to my thesis, 13 days and counting.
M-x lurk-mode-on
> On Sun, 3 Oct 1999, Laserlight wrote:
> So, you astronomer blokes, once again we're going to call on
again, i'm not an astronomer, but here's my 0.02 E's worth (incidentally,
anyone got any suggestions for doing the euro sign in ascii?).
<arrogance>
Bode's law does not represent any physical truth - it's a mathematical
curiosity, as is the fact that the sun and moon have the same apparent size
when seen from the earth. in fact, it illustrates the principle that if you
look hard enough, you can find a mathematical correlation between any set of
things!
</arrogance>
i seem to remember reading about orbital resonances affecting stability (in
Nature, iirc); it seems that if you have two planets in orbits with highly
resonant periods (ie, with a low lowest common multiple, eg in a ratio like
3:2 or 4:7), then interactions between them destabilise the orbits. i'm not
entirely sure about this, but it would suggest that if you have a massive
planet at some distance D from the star, you would not
expect to see planets ate distances of D/2, D/3, 2D/3, 3D/2, 4D/3, etc.
mind you, i could be utterly wrong about this. i've got a memory like a
sieve of Eratosthenes - there's no way of predicting what it'll catch.
anyway, this doesn't help you with placing the massive planets in the first
place:(. i'd suggest that heat from the sun would mean that
close-in planets would be rocky, intermediate ones gassy and far-out
ones icy. from the distribution of elements in the system (lots of hydrogen
and helium, quite a lot of oxygen, nitrogen and carbon, not much silicon and
iron), you could guess at the mass distribution: all that H/He goes into
gas giants in the middle, the O/N/C and some of the H into ice
sub-giants
(water, ammonia and hydrocarbons) at the edge and the silicon and iron into
little rock worlds near the sun. thus, if you have more silicon, you get more
rock worlds; more nitrogen, more ice worlds.
as for massive planets in very close orbits, they're either staggeringly huge
rocks, or the astronomers have muffed it up again. i know which option my
money's on:).
tom
G'day guys,
Just to through another "I know just enough astronomy to be dangerous" into
the mix....
An article I read in New Scientist a fortnight ago discusses one of the latest
theories in planet formation and the positioning of the gas giants. Basically
they form at about the position of Jupiter, but then collisons, near misses
and gravitational interplay sees them migrate to more stable spots. So far
there's pretty good evidence to support Jupiter having migrated in 0.5 AU and
Uranus migrated out 5 AU over the first 100 million years of the Solar System
then they got to fairly stable positions and stuck there. This theory is being
further supported by the relative positions of the new planets being found. In
one system they've uncovered there's a big gas giant at 0.8 AU another at 1.5
AU and another at 2.3 AU (or something like that I'll have to check the
articale again), two of the three are in almost perfectly circular orbits, but
the other one (middle one if I remember correctly) is in a very elliptical
orbit as that matches the best stable state (its inclination to the plane is
VERY close to that predicted by this theory).
Bottom line, mathematicians get bored/awed and look for neat 'laws'
everywhere (I've been guilty of that on a few long train trips) and as we
know more (n > 1 solar systems) we're going to have to re-write what we
know about planet formation anyway so just stick them little old planets where
ever you damn well like;)
Cheers
Beth
> G'day guys,
into
> the mix....
[snip]
> Bottom line, mathematicians get bored/awed and look for neat 'laws'
Doesn't Cole's Law apply in this case?
Jon (GZG)
> Cheers
> On Wed, Oct 06, 1999 at 01:05:04AM +0100, Ground Zero Games wrote:
Thinly sliced cabbage?
I prefer Martin's Law, because I got credit for it on an exam once: "Because I
said so."
snip snip
Beth, who was being serious, said:
> know more (n > 1 solar systems) we're going to have to
St^3 Jon, who was not, said
> Doesn't Cole's Law apply in this case?
Chopped cabbage with mayo and pickle?
G'day Jon,
> Bottom line, mathematicians get bored/awed and look for neat 'laws'
Sorry Jon, I've either forgotten this one or I'm just plain ignorant, can you
please enlitten me 'cos I guess your not referring to the one that says:
Shredded cabbage goes great with shredded carrots and mayonnaise...?
Cheers
Beth
> At 12:17 PM 10/6/99 +1000, Beth wrote:
<groan>
Oh, man, where's the Narn Bat Squad when you need it?
> Beth Fulton wrote:
> G'day guys,
into
> the mix....
(New Scientist stuff snipped)
> Bottom line, mathematicians get bored/awed and look for neat 'laws'
You mean we have will have to just make up something? Fooy guys...no solid
science laws to base this on! 8D
> Jon (GZG) wrote:
> >Bottom line, mathematicians get bored/awed and look for neat 'laws'
You lost me there. Do I use the coleslaw to stick the planets in their orbits,
or the gas produced after eating too much of it to create the planets in the
first place...?
> G'day Jon,
Sorry, Beth, it was late at night and I just couldn't resist it..... <VERY BIG
GRIN!!>
Jon (GZG)
> Cheers
G'day Jon,
> Sorry, Beth, it was late at night and I just couldn't resist it.....
<VERY
> BIG GRIN!!>
No problem;)
I've got to look harder for the twinkle in the i of the email (I'd hope for
visual email to avoid the problem, but then you'd all get to actually see me
and that'd destroy all your hopes and dreams!);)
Cheers
Beth
> Tom Anderson wrote:
Well, I always liked to assume that was no coincidence, but rather an
indication that Luna had been *moved* into position by some intelligent power
that had a distressing amount of energy at its command.
A Japanese comic used the same idea a while back. I think it was Outlanders or
something by the same author. BTW they also had organic space ships.
Mike
> A Japanese comic used the same idea a while back. I think it was
Yes, that's the one, by Johji Manabe - wonderful series. It was also a
primary source of inspiration for our new Phalon ships!
Jon (GZG)
> Mike
> Yes, that's the one, by Johji Manabe - wonderful series. It was also a
Yep see:
http://www.animenation.com/freethought/outvol3.html
http://store1.yimg.com/I/freethought_1552_213017096
Thats a phalon alright.
also
Aliens from the Santovasku Empire will purify Earth by destroying all of
humanity.
the name Santovasku seems strangely familiar....
> Yes, that's the one, by Johji Manabe - wonderful series. It was also a
<grin>
Clever chap. Have a toffee..... ;-)