OTS: The Lost World

Specifically, the one that isn't between Mars and Jupiter.
Old timey SF sometimes explained this gap by supposing that there
was once a planet where the asteroid belt is and that it suffered
some kind of calamity, from offering a moral lesson by blowing itself
up to simple bad luck, like having a contra-terrene matter world
collide with it.

It takes a surprising amount of energy to disrupt a planet [1]
especially if it is large enough to be called Earthlike (which a lot
of classic SF prefered as a default size for a world). A more recent
model is that Jupiter prevented the formation of a world in that
region.

An even _more_ recent model, seen in New Scientist, is that
there's a little bit of evidence to suggest that there could have
been a world in the belt, perhaps the size of Mars, but in the course
of the evolution of the solar system, it either got dropped into the
sun or flung out into the interstellar depths. Unfortunately, I
suspect the timing of this is such that it isn't useful to SF
writers: it should have been ejected so early that no interesting
chemistry (like, say, us) would have occured. This is a shame.

Of course, this would just be a specific example of a
general case: when stellar systems form, a lot of the material
in the system will be ejected from the system early on. There
might be tens of worlds out there for every one that ended up
in a stable (well, stable-ish. I think Mercury gets ejected in
one billion years [2]). Interestingly, if they were ejected before
the sun entered its T Tauri stage, they might have dense primordial
atmosphere thick enough to keep the surface above the melting
point of water.

Another interesting implication is that there have to
be a lot more rogue planets than stars, so if we encounter a
star as close as distance N every umpty million years, we should
encounter a rogue world far more often. Given that the odds
of such a world coming into the solar system proper are slim,
this may not be esp story rich.

ObSF: SATAN'S WORLD.



1: I know what you are going to say: "But what about that new model that's
been on the news, the one where Mercury got hit so hard that half its mass
was blown into space (and a million billion tonnes of it ended up on
Earth)?" Mercury was a lot smaller than the Earth even before the Big
Bump and also things move faster down there by the sun. Double the
speed, quadruple the kinetic energy.

2: This suggests that mature worlds could find themselves lobbed into
deep space, which is a fruitful situation for stories.

ObSF: A PAIL OF AIR. Also some terrible Wolheim where it turns out
Pluto was a visitor, I think.
--
http://www.cic.gc.ca/english/immigrate/
http://www.livejournal.com/users/james_nicoll
.

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