There were sounds of explosions in the space battle.

Although I suppose you could argue that the explosions would be heard on the ships that suffered them....

The setup was "A new solar system with dozens of worlds and hundreds of moons." I suppose a yellow giant star would have a much wider habitable temperature belt (albiet much further than 1 A.U from the star), and it's possible that terraforming could generate greenhouse effect conditions on the further worlds and moons.

Really, you can't overestimate the usefulness of being psychic in combat. Long as you're the least bit athletic, you will not get hit.

But River did get hit, on more than one occasion. It's just her opponents weren't superhumanly strong, so she could shake it off and continue. Buffy's punches can deform metal and shatter bricks, and just as importantly she can stand up to similarly strong blows. I think one solid hit would put River down—the questions would be "is she armed?" and "can she get in a lethal cut before Buffy realizes she has to fight in earnest?"

The only time there was "sound in space" was during the final space battle, which I'm sure was Universal going "No, you can't have all these things shooting and blowing up with no sound effects". The rest of time there was only noise in atmo, breaking atmo or entering atmo.

As Mr. Broom said, we heard dull thumps when the cannon was being fired in space, but one could argue the audiences' "vantage point" was either from within Serenity or with the person firing the cannon (I can't remember if it was Jayne or Mal.) during that scene.

Honestly, I think it worked well as a compromise, because most of the space scenes are properly soundless and carried by the music, but the masses get their SFX-happy space battle.

See, I'm still hoping for Asian former browncoats in the next movie.

And now, I must buy the Serenity tpb in spite of my plan to own the comics.

The setup was "A new solar system with dozens of worlds and hundreds of moons."

They also showed a diagram of the entire system early on.

I suppose a yellow giant star would have a much wider habitable temperature belt (albiet much further than 1 A.U from the star), and it's possible that terraforming could generate greenhouse effect conditions on the further worlds and moons.

Color and temperature have to do with size of the star. All yellow stars are pretty much the same size and temp. A blue giant (like Rigel in Orion) is very hot, and would have a very large habitable zone, except it also puts out way more of the nastier forms of EM radiation than humans could really deal with.

The problem with greenhouse effect is that as you get farther away from the star, the amount of solar energy reaching the planet drops off as a function of the square of the distance, so the effect doesn't work nearly well. Titan, which has a slightly thicker atmosphere than Earth, and is only about midway to the edge of our solar system, has a surface temperature of -178°C. That's colder than Minneapolis in the dead of winter. And you can't add a lot more in the way of greenhouse gases without killing the people.

You guys are clearly forgetting that they are using science.

My tendency with sci fi is to go, "Anything can be explained if we assume super-advanced technology exists."

My tendency with sci fi is to go, "Anything can be explained if we assume super-advanced technology exists."

Which means they should have a faster-than-light drive, and therefore don't have to be stuck in a single solar system. Or they could have a single solar system, just with fewer planets.

Does anyone need the solar-system thing to be correct badly enough that they'd require ships like Serenity to have warp drive? To me, that would be much more ridiculous.

I'm not requiring Serenity to have an FTL drive of any kind. I'd just prefer that the universe Serenity exists in make a little sense. Doesn't mean you can't tell good stories in that universe, but it's annoying to me that he would get that so wrong while sweating the detail of having Jayne wrap Vera in a spacesuit so that it would be able to fire in a vacuum (in total silence).