The Daily Backstory

One photograph contains 42 Suns and took an entire year to make. They trace a figure eight - and that shape exists precisely because the photographer did not wait for the Sun to reach due south before pressing the shutter.

In 1887, some 40 artists signed a letter demanding that Paris halt construction. When the tower's 20-year concession expired, it was not demolished - not because people had finally warmed to it, but because it had first made itself useful.

It is brighter than the brightest part of the Milky Way, yet almost no one has seen it. Its thousand-year-old name is the false dawn. Most remarkably, the dust behind it falls into the Sun within a few million years, so the fact that it is still here is itself a clue.

An alphorn has no keys, valves or finger holes. It can play only the notes its column of air permits. The 11th of those notes falls almost half a semitone below any key on a piano, and the Swiss have never tried to tune it away.

A man dives into Chongqing's brown Jialing River. The photograph raises three questions: what changes a river's color, why two rivers resist mixing, and why cold water is most dangerous in the first minute.

Gamma rays pass through any ordinary lens, so they cannot be focused into an image. Berkeley's new telescope takes another approach: let each photon collide inside a detector, infer the angle of its deflection, then draw its possible origin as a ring on the sky.

In 1923, a highly experienced observer announced that he had measured the rotation of the Triangulum Galaxy, M33. Eighty-two years later, its rotation was truly measured - at one-six-hundred-and-fiftieth his figure. And this autumn, you may be able to see the galaxy with the naked eye.

Winnats Pass in England's Peak District looks like the roof of a cave collapsed. Geologists say otherwise: it began as a channel between two reefs in a tropical sea, lay buried for 300 million years, then was cut open again by glacial meltwater.

Bulgarian kukeri go from house to house in animal skins, masks and bells weighing tens of kilograms to drive out evil. But the pink-walled house in this photograph has lost its roof - and 167 Bulgarian villages have no residents at all.

Fifty years ago, NASA rolled its first space shuttle out of a California hangar. It was supposed to be called Constitution, and the ceremony was deliberately set for Constitution Day. Fans changed the name, but the date belonging to another name remained.

Webb has photographed an open-lidded 'Treasure Chest' in the Carina Nebula. Its shape is no accident: follow the point of the pillar and you reach the thing slowly burning it away. The least conspicuous stars inside will outlive the chest by thousands of times.

Burgundy's famous Côte d'Or is not the side of a mountain but the face left behind when the crust split. By a ledger kept for more than six centuries, September 17 is just when Burgundy should be starting its harvest. In 2026, it began on August 15.

A Samburu warrior bears traditional scarification on his chest and a Catholic rosary around his neck. Why can the two coexist? The answer is not 'tradition versus modernity,' but a single word: in the Samburu Bible, God is called Nkai.

In early September, Anak Krakatau erupted continuously for 25 hours and eight airports closed. It does not simply grow through eruptions, but lives through a cycle of growth, collapse and regrowth - a mechanism described in a 2012 paper, six years before the unwarned tsunami of 2018.

Two streams of gas rotate in opposite directions inside the Black Eye Galaxy. Their existence suggests that this orderly-looking spiral once swallowed another galaxy, while our own Milky Way is doing the same thing now.

Mexico's national day commemorates not the day independence was won, but the day the uprising began - when a 57-year-old priest stood in a church courtyard and named a price for recruits. No verbatim record of what he said survives.

September is when Arctic sea ice reaches its annual low, and officials have not yet declared this year's minimum. Sea ice is not an extension of the land. It is the ocean's lid, and every polar bear hunting strategy attacks from above at prey below.

In 1983, a sea urchin nearly vanished from the Caribbean, and reefs changed within two weeks. Forty-three years later, the cause remains unknown. Now researchers are trying to raise its young in the laboratory - and those young look nothing like sea urchins.

Two astronauts look up at rocket boosters inside Kennedy Space Center. But the real subject is the room behind them: its extraordinary height was determined not by the rocket, but by the crane hook above it.

At noon yesterday, Venus emerged from behind the Moon over a village in France. The two crescents in the photograph have strikingly different shapes - the same difference Galileo used to overturn the geocentric model. In Yunnan last night, people saw the other half of the occultation.