May 4

The Dark Side of the Moon

On the night of May 4, 1783, William Herschel—the greatest observational astronomer of his age, discoverer of Uranus, builder of the largest telescopes in the world—turned his 10-foot Newtonian reflector toward the dark side of the Moon and saw something that shouldn't have been there…

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The entry in Herschel's observing record is brief and exact, as his records always were: "May 4, 1783. I perceived in the dark part of the Moon a luminous spot. It had the appearance of a red star of about the 4th magnitude. It was situated in the place of Hevelii Mons Porphyrites, the instrument with which I saw it was a 10 feet Newtonian Reflector of 9 inches aperture." Hevelii Mons Porphyrites was the old name for the crater we now call Aristarchus—a name the ancient Greek astronomer Aristarchus of Samos would have found bitterly ironic, given that he proposed a heliocentric universe seventeen centuries before Copernicus and was accused of impiety for it. The crater named after him sits in the Moon's Oceanus Procellarum, "the Ocean of Storms," and it is the brightest feature on the entire lunar surface. On the night of May 4, 1783, it was sitting in total lunar darkness—and it was glowing red.

The Music and the Spheres

Born Friedrich Wilhelm Herschel in Hanover in 1738, the son of a military musician, William Herschel initially followed his father into music, then emigrated to England at nineteen to escape the chaos of the Seven Years' War, and spent two decades as an organist and music teacher in Bath before his obsessive hobby consumed him entirely. He ground his own telescope mirrors by hand—literally by hand, hours at a time, sometimes feeding himself spoonfuls of food between strokes because he couldn't bear to stop. He slept in snatches. He observed every clear night. In 1781 he had pointed one of his homemade instruments at a faint smudge in Gemini and realized it was moving: it was a planet, the first new planet discovered since antiquity. He named it Georgium Sidus in honor of King George III. The astronomical community renamed it Uranus. George III gave Herschel a royal pension of £200 a year and a house near Windsor Castle, where the King could visit him and look through his telescopes whenever the mood struck.

By 1783 Herschel was the most credible observational astronomer in Europe. When he reported something, it was listened to. And what he reported on May 4th was a red light burning in the lunar darkness—visible, steady, unmistakable through a precision instrument built by the man who had found a planet.

An Appeal to the King

The observation was never formally published in Herschel's lifetime. Rather, it circulated through correspondence—that invisible network of letters that constituted the scientific internet of the eighteenth century. A Portuguese scientist named J.H. de Magellan, then resident in London, wrote to Herschel asking for details of the reported lunar volcano, as it was already being described. Herschel's reply, eventually published in 1912 when his collected papers were finally edited and released, contained a passage that has a distinctly urgent quality for a man normally so composed:

"Will you do me the favour to acquaint the King with these circumstances; and if his Majesty would wish to see the Moon, the best time for viewing the Crater, which continues still to be considerably luminous, will be this evening between 9 and 10 o'clock. I will be at Windsor in good time to see the King's ten-foot telescope brought out and prepared, if it should please his Majesty to have it done."

The image this conjures—Herschel dispatching a letter to get King George III out of bed and to his telescope on a specific evening to observe a glowing crater—says something important about how seriously he was taking what he'd seen. But this was no hedged, cautious report; Herschel was convinced. He believed there was something actively luminous on the lunar surface, and he wanted the King to see it before it faded.

We'll never know if George III made it to the eyepiece that night.

The Lunar Civilization Next Door

The red glow of 1783 was not an isolated curiosity in Herschel's thinking. It fit into a broader cosmological worldview that the history books tend to hurry past, because it sits so uncomfortably alongside his genuine scientific achievements.

Herschel believed the Moon was inhabited. Not tentatively, not as a philosophical speculation, but as a working conviction that shaped his observational program for decades. When he studied the lunar surface through his telescopes he saw what he interpreted as evidence of ongoing construction—regular geometric features that suggested intelligent design rather than geological accident. He mapped what he called the works of the Lunarians with the same meticulous attention he brought to double stars and nebulae. He believed the Sun was inhabited too, theorizing that sunspots were gaps in a luminous outer atmosphere through which the cool, solid, potentially habitable surface beneath could occasionally be glimpsed. He extended this principle outward to every body in the solar system.

To Herschel's mind, an empty universe was not just improbable but philosophically incoherent: why would a Creator of such evident fecundity leave all that real estate unoccupied? The plurality of worlds—the doctrine that other planets and moons harbored life—was standard educated opinion across the eighteenth century. Leibniz had held it, as did Halley and Kant. The boundary between natural philosophy and what we might now call speculative cosmology was not yet firmly drawn, and a man who had just discovered an entirely new planet was entitled to expansive views about what that universe might contain.

Still ... The idea that Herschel spent years mapping the construction projects of lunar inhabitants—and then saw their fires burning on the night of May 4th—has a quality that resists easy categorization. The greatest observational astronomer of his era, the man who would go on to discover infrared radiation, to catalog 2,500 nebulae and star clusters, to establish the shape of the Milky Way, was spending his clear nights watching for signs of life on the Moon. And on one of those nights, he appears to have seen something.

Transient Lunar Phenomena

What Herschel observed is today known as “Transient Lunar Phenomena,” or TLP: short-lived lights, glows, and colorations on the lunar surface that have been reported by observers for centuries and have never been definitively explained. The catalog of such reports is longer and more distinguished than is generally acknowledged.

In April 1787, Herschel saw the red glow again—this time at three separate spots near Aristarchus simultaneously, during the peak of the Lyrid meteor shower. He was now fully convinced he was watching active volcanism. Contemporary astronomical opinion was divided: his accuracy as an observer was so well established that the reports couldn't simply be dismissed, but neither could they be readily confirmed. The French astronomer Lalande, writing to Herschel, spoke for many colleagues in declining to commit either way.

The phenomena continued to be reported after Herschel's death in 1822. In November 1958, the Soviet astronomer Nikolai Kozyrev—director of the Crimean Astrophysical Observatory—observed a reddish glow near the central peak of the crater Alphonsus and managed to obtain a spectrogram before it faded. The spectrogram showed a spectral line characteristic of the C2 molecule at temperatures up to 2,000 degrees Celsius—which would be consistent with outgassing or volcanic activity. In 1963, cartographers at the Lowell Observatory reported bright red, orange, and pink spots near Aristarchus. Days later, astronomers at the Observatoire du Pic-du-Midi in the French Pyrenees photographed a wide luminescence in the same region and published their findings in Scientific American. In 1969, Apollo 11 astronaut Michael Collins—orbiting the Moon alone while Armstrong and Aldrin walked on its surface—reported a bright glow near Aristarchus that had also been observed simultaneously by astronomers in Bochum, West Germany.

None of it has ever been definitively explained. Current theories range from outgassing of radon and other volatiles through the lunar regolith, to electrostatic effects, to meteor impacts. The crater Aristarchus sits above one of the most geologically active regions of the lunar surface—a massive volcanic plateau called the Aristarchus Plateau—and there is genuine ongoing scientific interest in whether the Moon is as geologically inert as the standard model suggests. NASA's LAMP instrument aboard the Lunar Reconnaissance Orbiter has detected evidence of radon emanations from Aristarchus that could, under certain conditions, produce visible luminescence.

Herschel may have been right. He was almost certainly not seeing a lunar civilization ... but he may have seen something real.

The Moon as Mirror

For the Modern Occultist reader, the Aristarchus mystery sits at a particularly interesting intersection. The Moon has always been the threshold body in Western esoteric tradition—the boundary between the sublunar world of matter and change and the supralunar world of eternal forms. In Hermetic cosmology, the Moon is the gate through which souls pass in both directions: descending into incarnation, ascending after death. Its light is borrowed, reflected, secondary—and therefore, in the Neoplatonic framework, a perfect symbol of the world of appearances, of matter that does not generate its own illumination but only reflects what it receives from the Sun.

What Herschel saw on May 4, 1783, was the Moon generating its own light. In the darkness, in the part of the lunar surface that receives no sunlight, there was a red glow that did not belong there by any conventional account. He saw it with his own eyes through the finest instrument of the age, and spent years diligently watching for its return.

The Springer Nature paper on Herschel's lunar research notes, almost in passing, that the 1783 observation may have inspired Samuel Taylor Coleridge, fifteen years later, to write the haunting lines in The Rime of the Ancient Mariner: "While clombe above the Eastern bar / The horned Moon, with one bright star / Within the nether tip." A star within the dark horn of the crescent Moon—exactly the geometry of what Herschel had described.

The greatest observational astronomer of the age saw a red light where no light should be, and the greatest visionary poet of the age may have transformed that observation into one of the enduring images of the uncanny in English literature.

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