I read this decades ago.

The idea that there was in space, around some star, an "air" belt, like an asteroid belt, with enough atmosphere that people could live there without special life-support. Maybe there were also rocks and "dirty ice" blocks, but I am not sure. What definitely was there are huge trees, and people mostly have settled on these trees.

Since everything was rotating, Coriolis forces dominated the dynamics, so people who kept "flying" from one tree to another had developed new reflexes very unusual to us.

I do not remember much about the story itself.

I vaguely remember a very dangerous trip to a stable Lagrange point (due to the presence of a planet, probably just a planetoid, sharing the orbit of the air and the trees), but I don't remember why the trip was attempted. Possibly to recover some stuff, since in the story vagrant stuff would tend to drift towards stable Lagrange points (I believe the author did not have a very clear understanding of stable Lagrange points but this is irrelevant).

It was either a rather short novel, perhaps a rather long novella, I am not sure.

1 Answer 1


This is Niven's The Integral Trees (1984), or possibly its sequel The Smoke Ring (1987). The stories are set in orbit around a neutron star that has a zone of atmosphere in orbit around it at the habitable temperature of liquid water. (There is another, yellow, star that is the binary companion of the neutron star that provides light for photosynthesis, but the smoke ring orbits close to the neutron star.)

People live on the titular kilometres-long trees, which are named after the shape of an integral sign (∫) although as described in the story they are more angular, like 2 hockey sticks taped butt-ends-together. The trees are tidally oriented perpendicular to their orbital motion, and the winds generated by the differing orbital speeds between the top and bottom drag the foliage into "tufts" at each end of the tree. (Except for the tufts, where it is possible to pull moisture out of the moving air, the trees are mostly barren.)

The "satellite" you're talking about is actually Goldblatt's World, a gas giant that is the source of the atmosphere in the smoke ring. Reviewing the plot I believe you're actually recalling the second book (The Smoke Ring) which has Kendy send the people on Citizen's Tree to visit "The Admiralty" who have colonized "The Clump", a semi-stable grouping of ponds and vegetation that orbits at Goldblatt's World's L4 point.

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    Yes. That perfectly fits my memories. Indeed now I remember "the interplay between gravity and the winds generated by the differing orbital speeds between the top and bottom." That was fast ! Probably the first one, it didn't feel like a sequel missing the first book. Or possibly I read both, in the right order. That was long ago.....
    – Alfred
    Jan 5, 2022 at 17:56
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    At one point, they were sold in a single volume.
    – Zeiss Ikon
    Jan 5, 2022 at 18:00
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    The Smoke Ring was gas torus from the gas giant, Goldblatt's world, known as "Gold" to the inhabitants, held and compressed by tides from a neutron star, and illuminated by the binary companion of the neutron star. Trust me, Larry Niven had the orbital mechanics and L4/L5 points right.
    – Zeiss Ikon
    Jan 5, 2022 at 18:03
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    @Alfred Even from a gas giant in a tight orbit around a neutron star, the "well" at L4/L5 isn't deep enough to be hazardous -- that's just where everything in the Smoke Ring is densest; trees closest together, air thickest, most water and solid material to be found. Danger is in getting too far around the ring from there or too far inboard, outboard, port or starboard, with the air getting thinner, or being on the wrong half of a tree when that happens.
    – Zeiss Ikon
    Jan 5, 2022 at 19:24
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    @DavidW Danger from people ! That's possible. I believe I really remember the trip close to the center of the L4 as dangerous, but it might well be because bad encounters could happen there, not a problem of gravity. Gravity as the cause could be a false memory, danger I am pretty sure.
    – Alfred
    Jan 5, 2022 at 22:51

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