Rotation and orbit have nothing to do with it. Here are some consideration that matter.

First off, planets are round because, past a certain size, gravity is strong enough that the rock behaves like a liquid. Therefore, it is reasonable to assume that two rocky planets with similar and composition will have the same size and therefore the same gravity.

The composition matters because it influences the density. Earth has a dirty great lump of iron at its core so it is fairly dense. That same iron core is generally believed to be responsible for our magnetosphere, which in turn appears to be a key reason why we still have an atmosphere.

So if you want a planet with an atmosphere and gravity around 1g, you probably want something a *lot* like Earth. However, we have no idea how evolution might have gone if the entire ecosystem had been subjected to more gravity, so we have no idea if "gravity around 1g" is actually important.

Planets with higher surface gravity would, of course, be harder to escape from, and chemistry is the same everywhere in the universe, so there is probably an upper limit to the size of a planet that you can use chemical rockets to escape from. But it is entirely possible that this only presents civilisations with a problem for a few decades or so.

If gravity were 2g, *we'd* be shorter and have bones with a larger cross-sectional area. We'd be more like elephants and less like monkeys. Mountains would also be lower, seas quite possibly shallower and therefore the ecosystem as a whole less diverse in the environments it could offer.

I'm interested.

But they're out of glossy brochures.

Can you tell me if the time-shares on Keppler 22b may be exchanged for similarly outfitted time-shares on Ariel or Titania during Jump the Shark season? (They've been sold out now for several powers of 10. And the waiting list is practically a light year long.)

The wife and kids are anxious to give shark jumping tumble.

But if there's nothing to go there for why bother.

Because its there. No one thought there was much in the Arctic, but people still went there.

Re My question is.. → #

At warp5 it will take 4.8 years to get there.

Re : At warp5 it will take 4.8 years to get there

Pity it's just a fictional means of travel !

They listened to the latest weather report.

Of course ... it would have been 600 light years out of date!

Like the old Soviet Union you mean? They took so long to put a man on the moon that the entire country had ceased to exist before they managed it, and they had a head start.

Democracy: the least bad system. Knock it, by all means. (It's your right and quite possibly your duty to *knock* it.) But don't go believing that a benign dictatorship would be better. That way lies non-benign dictatorships.

Ummm ... you realise they'll just be seeing the fluctuating light from a sun as the planet MOVED in front of it 600 years ago? You have eyes - you can see stars - most of which are far further away than a mere 600 light years... or did I miss something? Perhaps the bridge or the goats?

Way to troll Joerg dude!

The information reaching Kepler is, yes more or less 600 years old.

The star might be going nova right now and engulfing said planet, we wouldn't find out about it for another 600 years. It doesn't change the fact that 600 (or so) years ago, Kepler 22b exhibited characteristics associated with the development or support of life.

Scale.

Even a really good closed system is going to be losing resources over time, so they'll need to resupply from time to time.

That said, resupply from comets and asteroids is very likely to be orders of magnitude easier - harder target to aim for but much easier to mine when you get there.

A mobile closed system is also not going to be able to support a large population - nothing like the size you could comfortably fit on a single continent on a planet, and probably not even a large city.

They make it up. The set of people who are good at painting and set who are good at physics has quite a small intersection, so it's quite possible that they're *really* just making it up.

Given the current state of AI and the rarity of programs that exhibit real creativity, writing a program to do the same would be quite a bit harder than "making it up" yourself, so I don't think there's any money to be made.