Moon

The Moon is both a familiar subject of astronomical study and the source of an unforeseen crisis for the Fifth Men. Its orbit, long understood to be changing over immense spans of time, begins to contract toward Earth far earlier and faster than their science predicts. The approaching catastrophe overturns their confidence in a coherent body of knowledge and makes humanity’s departure from its native planet an urgent necessity.

Orbital history and scientific expectations

The Moon’s motion had been studied since remote antiquity. Even the First Men understood the broad pattern: it would first recede from Earth and later return, eventually reaching a critical proximity at which it would break into fragments like the rings of Saturn. The Fifth Men had thoroughly confirmed this account. Their expectation was that the Moon would continue moving outward for hundreds of millions of years before its eventual return.

That long-established picture made the new observations especially disturbing. The Moon had not merely stopped receding; it had begun approaching Earth, and the contraction was comparatively rapid. The anomaly was not a minor adjustment to an obscure calculation. By this stage, the Fifth Men had tested and interlinked their natural sciences so extensively that a small discrepancy between fact and theory could unsettle the whole structure of knowledge.

The anomaly and its consequences

The Fifth Men repeated their observations and calculations and proposed ingenious explanations, but none disclosed the truth. As the years passed, the distance between Earth and the Moon continued to decrease with increasing speed. The eventual explanation—that a planet’s gravitation was connected with its cultural development—was left to a future, more brilliant species to discover. For the Fifth Men, the cause remained hidden while the trajectory and its danger became harder to dismiss.

If the acceleration continued, the Moon would enter the critical zone and disintegrate in less than ten million years. Its fragments would not settle into a stable ring: they would soon fall upon Earth. The heat of their impacts would render the planet’s surface impossible as a home for life. Ten million years might seem effectively endless to a short-lived species, but the Fifth Men thought in terms of the race’s future and recognized that their social policy had to be governed by the threat.

From planetary crisis to departure

The discovery interrupted a period of profound melancholy. The Fifth Men had been haunted by the tragic past; the Moon’s erratic motion redirected attention toward an alarming present and an uncertain future. Some initially doubted that the abnormal approach would continue, but the passage of years made that reassurance increasingly implausible.

Explorers of the past also tried to inspect the future, hoping to establish that human civilization would remain discoverable on Earth in even the most remote ages. Their attempt failed. They mistakenly supposed that future events, unlike past events, did not exist until the advancing present created them. With no assurance that humanity could survive on its home planet, the Fifth Men concentrated research on travel through empty space and the habitability of neighboring worlds. Mars lacked water and an atmosphere; Venus had a dense, moist atmosphere without oxygen, was almost entirely covered by shallow ocean, and was too hot for humans to survive even at its poles.

The Moon amid humanity’s energy history

The approaching Moon presents a danger fundamentally different from the resource shortages that had previously tested civilization. The First World State had relied heavily on Antarctic coal, and the exhaustion of its supplies precipitated collapse. Later, the discovery of an effectively inexhaustible power source through the annihilation of matter offered a striking contrast: the Fifth Men could command immense energy and automate the economic routine, yet material abundance could not make Earth safe from a lunar catastrophe.

In this way, the Moon changes the scale of the Fifth Men’s planning. It is not simply an astronomical object whose future can be left to distant generations; its altered orbit makes planetary survival the condition around which humanity must organize its next era. The threat compels a transition from civilization on Earth to the search for a home beyond it, while the physical cause of the Moon’s behavior remains, for this species, unexplained.