The Solar-System Catastrophe from a Dark Body Collision transformed an anticipated, manageable stellar crisis into a disaster that rearranged the planetary system. The Eighth Men had begun preparing for the Sun’s eventual collapse; a newly detected intruder instead made their long-range plans obsolete, forced humanity’s future onto Neptune, and then passed through the system with consequences extending far beyond that world.

The solar crisis and the first migration plan

After a long period of peace and scientific advancement, the Eighth Men detected signs that the Sun would eventually collapse into a dense, weakly radiating White Dwarf. They estimated that the change would begin in twenty thousand years and that, in another fifty thousand, Venus would probably be frozen and uninhabitable. Their proposed refuge was Mercury, which was becoming less intolerably hot. To make that migration possible, they had begun giving Mercury an atmosphere and breeding a species able to adapt eventually to extreme cold.

That project was already under way when astronomers discovered a vast volume of non-luminous gas at a distance from the Solar System. Calculations showed that it and the Sun were approaching on paths that would meet at a tangent. The discovery changed the scale and timetable of the danger: the intruder was expected to make the Sun flare and expand prodigiously, rendering life impossible on nearly every planet. The Eighth Men’s preparations for the Sun’s slow transformation could no longer answer the more immediate threat.

Neptune as a precarious refuge

The calculations left only Uranus and, more probably, Neptune as possible refuges from the Sun’s coming flare. The three planets beyond Neptune were expected to escape the heat, but they were unsuitable for other reasons: the two outermost would remain glacial and lay beyond the range of the Eighth Men’s imperfect Ether ships, while the innermost was a bare iron globe without atmosphere, water, or the ordinary covering of rock.

Neptune offered a possibility, not a ready-made home. Its atmosphere was unsuitable, its gravity would make an ordinary human body an intolerable burden, and the planet would remain too cold to support known life until after the collision. The migration therefore required preparation before settlement. Ether ships carried out chemical changes intended to improve the atmosphere, and the rediscovered process of automatic matter annihilation supplied energy to warm a limited area where life could survive until the Sun’s later rejuvenation. Specially designed vegetation was established there; animals were judged unnecessary. The Eighth Men then transported a specially designed human species, the Ninth Men, to Neptune.

The Eighth Men themselves could not settle there. Neptune’s immense gaseous envelope produced a gravitational pressure greater than that on the floor of the Venerian ocean, and its mass made even their giant bodies difficult to support. They could leave their Ether ships only briefly, wearing steel diving suits. Once the settlement was complete and humanity’s most precious material relics had been transferred, they returned to the archipelagos of Venus to await the end.

The intruder’s passage through the planets

Neptune narrowly missed colliding with the dark stranger. Uranus and Jupiter were also outside its track, but Saturn was not: a few years after Neptune’s escape, Saturn was engulfed together with its rings and satellites. The resulting incandescence was described as only a prelude to the larger disturbance.

The intruder then ploughed through the asteroids and tangled the planetary orbits, its passage compared to a finger thrust into a spider’s web. Mars escaped. Earth and Venus were caught in the stranger’s blazing wake as it continued toward the Sun. The account does not detail what happened to life on those two planets during this passage, but it makes clear that the disturbance had moved far beyond a threat to the Sun alone: planetary paths and the established distribution of human habitation were now exposed to the intruder’s violence.

The transformed Solar System

The dark body finally struck the Sun. Afterward, the system’s centre was no longer the familiar star: it had become a star nearly as wide as Mercury’s former orbit. The collision thus fulfilled neither the Eighth Men’s original timetable nor their expectation that migration to a prepared world could neatly secure humanity’s future. Neptune had received the Ninth Men and the most valued material relics, but the wider planetary order had been violently remade around them.

The episode’s catastrophe is also an energy and survival crisis. The Eighth Men’s refuge depended on immense technical intervention—atmospheric alteration, transported vegetation, and a steady supply of energy from matter annihilation—yet even those measures could not protect the whole Solar System from a force on the scale of the intruder. The collision turns a carefully managed migration into a precarious inheritance: the Ninth Men reach a world prepared for life, while the older planetary home and the star that governed it are caught in a transformation no prior plan had anticipated.