From user HDE 226868,

profile for HDE 226868 on Stack Exchange, a network of free, community-driven Q&A sites :

Yes, this meta question is on the right site. Trust me.

Worldbuilding Stack Exchange has a blog, and it was suggested that we put together a post about the recent discovery of four more planets around TRAPPIST-1. I'm going to try to write it up the next couple days, and we'll probably publish it in a couple weeks (though no promises).

We also want to steal take inspiration from content on Astronomy Stack Exchange about TRAPPIST-1, especially since we've gotten a slew of questions about it in the last 24 hours. The point of all this is that it would be fantastic if members of the Astronomy Stack Exchange community could give us some ideas to work with. I've already read through the discovery paper, but obviously, plenty of folks here know more about TRAPPIST-1 and exoplanets in general than I do.

So, what would you like us to put in the post? Discussions of orbital stability? The formation of the planets outside the frost line? A brief overview of ultracool dwarfs? Liquid water? Something else entirely?

We want to use this blog post to promote cross-site interactions, and also to give some publicity to Astronomy Stack Exchange.

Original post on Astronomy.SE

Why not have Space Exploration participate as well?


3 Answers 3


Worldbuilding's mandate:

Worldbuilding Stack Exchange is a question and answer site for writers, artists and others using science, geography and culture to construct imaginary worlds and settings.

So, I take it the matter here is what fascinating fictional worlds can be created based on the discoveries at TRAPPIST-1. That would seem to be a matter that could go all over the place. Where do exobiologists fall in the Stack Exchange ecosystem? Planetary science is shared by Astronomy and Space Exploration, I think there are lots of interesting things to ponder there.

Things I wondered about:

  1. How space travel between those planets would work. What are the delta V budgets, how often are good trajectories available? They are all tidally locked, and being so much smaller than their star, their Lagrange points with the star would be fairly close to them - would space elevators on those planets work better or worse than they do for rotating planets?

  2. What kinds of temperature gradients are we talking about between the sun-ward and space-ward hemispheres of these planets? How much can an atmosphere or oceans moderate that?

  3. What would communications between these planets be like? Is radio noise from the star a big deal?

  4. Would wind turbines and solar power work extremely well on these worlds, giving early industrial societies an interesting option we didn't have?

Now that I've listed them, it seems to me that most of those questions would be legitimate questions on SX. But, I don't really have time... If anyone thinks they are good questions for our site, please go ahead and ask. :)

  • $\begingroup$ Oh - gravity assist opportunities... also interesting... $\endgroup$
    – kim holder
    Commented Feb 23, 2017 at 19:19
  • $\begingroup$ These are excellent ideas. I think they're going to make it. $\endgroup$
    – HDE 226868
    Commented Feb 23, 2017 at 21:59
  • $\begingroup$ I think that, as far as question 4 goes, wind turbines and solar power would be about the same as on the Earth. One of the planets at least, receives almost the same flux as the Earth does. $\endgroup$
    – Phiteros
    Commented Feb 23, 2017 at 23:25
  • 1
    $\begingroup$ @Phiteros but because they are tidally locked, i thought that would mean they would have strong constant winds around their terminators. And on the day side, the sun never sets. For that matter, i wonder what kinds of currents are set up by atmospheric conditions like that. $\endgroup$
    – kim holder
    Commented Feb 23, 2017 at 23:48

A very good question was raised during the press release - somebody asked about if material could be transported between the planets because they are so close - kind of like how material ejected from Io can end up on Europa.

It was mentioned in the press release (and I made a question about it on Astronomy) that the planets likely started further from the star and migrated closer to the star. So what if a civilization started on the planet closer to the star, and as it moved closer to the star, they had to develop spaceflight. Then they planet-hop and migrate their entire civilization and biosphere from planet to planet as the closer planets move out of the habitable zone and the further ones move in.


Astronomy is a better fit for that topic than our site, it's far beyond the realm of current space travel. Perhaps we could include a paragraph about Project Starshot, but aside from that...


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .