Re: Sky People's solar system
| From: | Padraic Brown <pbrown@...> |
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| Date: | Tuesday, January 19, 1999, 15:58 |
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On Tue, 19 Jan 1999, Christophe Grandsire wrote:
> I know
> also that you can't place planets wherever you want (I think the average
> radii of the orbits in our solar system follows a series of numbers that I
> don't remember (but I remember having seen it!)) and I want to make my
> solar system as "natural" as possible. So I need the average radii of the
> planets' orbits, and the corresponding time of revolution. If anyone knows
> the relation...
I have only one nitpick with this: there's no such thing as a "natural"
(i.e., normal!) solar system. We only know one real well (hence I suppose
the idea of an ideal or natural solar system!); and none of the others
that are being studied are at all like ours, beyond the basics. One I can
think of off hand has a gas giant up close to the star, and smaller
planets further out: in contravention of what seems "natural" to us, whose
gas giants are well away from the star. Thus, I think there is no real
harm in placing the planets more or less where you wish!
Besides, how different would our astronomy be if _we_ had a whopping great
gas giant right next door, perhaps in place of Venus!
> As far as I've designed the solar system, it has:
>
> - a sun (only ne) that is just a bit hotter than ours, so habitablme
> planets must be a little farther than our Earth from the sun.
Quite plausible; I believe current thought is that Venus and Mars are at
the inner and outer areas of the "life belt". At least the sort of life
_we_ are!
>
> - 13 planets (in fact 14 as there is a double one) and 2 asteroid belts
> which are placed, from the nearest to the farthest from the sun:
The more the merrier!
>
> - the smallest planet of the system, even smaller than our
> Mercury. It's so near to the sun that it is totally invisible at eyes'
> sight;
>
> - a double planet, the bigger the size of Mars, the smaller just
> slightly smaller. No atmosphere (to close to the sun), but visible.
Don't be too quick to assume that nearness to the star = no atmosphere.
Mercury has a sodium-helium-hydrogen atmosphere. Thin to be sure, but
there!
>
> - a planet as big as Earth, with no moon. In the habitable zone
> but too hotter to have life. The biggest volcanic activity of the solar
> system (makes it inhabitable).
Somewhat like Venus then.
>
> - the planet of the Sky People, slightly bigger and denser than Earth
> (just enough to have a gravity of 1.1 instead of 1). Exactly in the midddle
> of the habitable zone, so farther to its sun than Earth to its (it will
> make a year of 450 Earth days or so I think). 2 moons, one smaller than the
> Moon, the other bigger. I want them to be placed to have the same apparent
> radius as the sun (to have more possibilities of eclipses (sp?)) and I need
> their time of revolution around the planet to make a "small month" and a
> "big month" (for the Sky People's calendar). If anyone can help...
You might want to make them (the moons) rather larger than the solar
radius, for as time passes, planetary rotation slows and the moons will
move further away (as ours is). Thus, if the moons start out large and
somewhat close to the planet, by the time the Sky People pop into History,
the moons will be the right size and distance from the planet for complete
eclipses.
>
> - the first asteroid belt, with the biggest asteroids (some of
> the size of the moons of the planet of the Sky People).
>
> - a Neptune-like (or Uranus-like) gas giant planet. A dozen of
> moons. A very small ring.
I read recently that planetary rings and small moon(let)s go hand in hand.
I think it had to do with the planet's gravity ripping bits off the moons,
which form rings.
>
> - a kind of hybrid, to big to be a rock planet, to small to be a gas
> giant. A kind of very big rock planet with a very thick atmosphere. A
> fourth as big as the Neptune-like planet. five moons.
>
> - a gas giant with very thick rings, a little bigger than Saturn.
> Something like 30 moons.
>
> - the biggest planet of the system, a tenth bigger than Jupiter.
> 23 moons and a strange system of _two_ perpendicular rings, an
> equatorial ring and a polar one. As strange as it appears, the polar
> ring is stable. The last visible planet of the system.
Very odd and strange! Perhaps astronomers will eventually find turbulent
clouds of smashed debris where the two ring systems meet?
>
> - the second asteroid belt, with much smaller asteroids (due to both
> planets surrounding the belt).
>
> - another gas Neptune-like gas giant, 10 moons.
>
> - a solitary little rock and icy planet, maybe an ex-moon of the next
> planet (very possible as its orbit cuts the orbit of this planet). It has a
> small volcanic activity, hence a light atmosphere. No moon.
>
> - another gas giant, bigger than Neptune, with small rings. 9
> moons or so.
>
> - another rock and icy planet the size of Earth. No atmosphere. One moon
> the size of the Moon.
>
> - the last planet of the system, a Neptune-like gas giant with
> only two moons.
Why not a methane or ammonia atmosphere? Most of our planets and
moons seem to have some kind of atmosphere.
Does your system have an Oort Cloud or similar with which to rain comets
on your planets?
>
> As you can see, my solar system is already well defined. I need
> only to find the average radii of the orbits and the time of revolution
> for each planet (and the ones for the two moons of the Sky People's
> planet). That's why I need your help. Does anyone know at least those
> parameters for our own solar system (I'll extrapolate from it)?
In addition to distance from the Sun, I thought I'd add a couple of other
interesting data for you to consider: avg. dist. from Sun; length of year;
inclination of orbital plane (w/r to plane of solar system); inclination
of planetary rotation to that planet's orbital plane; temp. range.
1AU = 149,600,000km (approx.)
273 degrees K = a balmy 0 deg C
distance year inclin. inclin. temp.
of plane to plane deg K
Merc.: 0.037AU 88days 7d00m 0d00m 100-700
Venus: 0.723AU 225 3d23m 177d18m 700
Earth: 1.000AU 365 0d00m 23d27m 250-300
Mars : 1.520AU 687 1d51m 25d12m 210-300
Jup. : 5.202AU 4333 1d18m 3d07m 110-150
Sat. : 9.540AU 10759 2d29m 26d44m 95
Uran.: 19.280AU 30685 0d46m 97d52m 58
Nept.: 30.220AU 60188 1d46m 29d34m 56
Pluto: 39.830AU 90700 17d07m 98d00m 40
Padraic.
> Christophe Grandsire