Cold Open

It’s 7 AM on June 30th, 1908 in a village near the Tunguska River in Siberia, Russia.

A merchant sits on the front porch of his trading post, enjoying his breakfast. But as he eats, something extraordinary captures his attention. A bright, cylindrical object traversing the northern sky. It’s like nothing he's seen before.

His eyes widen with a mixture of curiosity and trepidation as the seconds tick by and the object maintains its unhurried trajectory. Until suddenly… the merchant drops his spoon and shields his eyes. The shape streaking through the sky disappears in a white flash as the sky is engulfed in a blinding, incandescent burst. Between his fingers, the merchant watches the light fade to a bright orange, and then an angry red.

As the sky changes color, the ground convulses beneath him, flinging the merchant from his seat. A guttural rumble moves through the earth and the merchant feels a blast of hot wind. He curls into a protective ball, trying to protect himself from the scorching heat.

Time seems to stand still as he endures this hellish ordeal, but after just a few moments, the chaos is over. The hot tempest abates, the shaking stops, and an ominous silence descends on the village.

The merchant and his fellow villagers will have no idea what just swept through their community. And for years, neither will scientists or researchers. Exactly what caused the Tunguska Event as the strange incident is named, will remain unknown for decades. But its mystery will eventually be revealed, thanks to the work of one determined scientist, whose expeditions into the Siberian wilderness will form the basis of modern theories explaining the peculiar explosion that confounded witnesses on June 30th, 1908.

Introduction

From Noiser and Airship, I’m Lindsay Graham and this is History Daily.

History is made every day. On this podcast—every day—we tell the true stories of the people and events that shaped our world.

Today is June 30th, 1908: The Tunguska Event.

Act One

It’s early 1921, in Siberia, Russia, thirteen years after the still unexplained Tunguska Event.

38-year-old Leonid Kulik scribbles down notes while he listens to a merchant describe the unusual events he witnessed over a decade ago.

Leonid is a mineralogist at the Soviet Academy of Sciences in Petrograd. A few weeks ago, he stumbled across an old newspaper report detailing some strange happenings in Siberia. Leonid instantly recognized the reports of a bright light, earth tremors, and fierce winds as a sign that a meteorite had struck the Earth nearby. Determined to confirm his theory, Leonid dropped his other research projects and set out for Siberia, hoping to find the meteorite’s remains.

But locating the space rock has not been a simple task. Right now, the newly declared Russian Soviet Republic is embroiled in a civil war, making travel dangerous. Fortunately, Leonid managed to reach Siberia safely, but upon his arrival, a new problem arose.

The region is even more vast than he imagined. With Siberia’s population spread across more than five million square miles, Leonid’s search for evidence and witnesses has been difficult. But the scientist has not lost hope of tracking down the meteorite. For weeks, Leonid has been traveling between towns and villages by train, collecting accounts from any eyewitnesses he stumbles upon. By now, he's collected plenty of colorful tales of the strange event, but none of the witnesses he’s encountered have any idea where a meteorite could have struck the Earth.

But today’s interviewee seems more promising. As the Siberian merchant recalls what he saw that morning, Leonid interrupts with a question. He asks if the man can describe in which part of the sky he saw the object. Leonid’s face brightens as the merchant says not only where in the sky it flew, but where he thinks it landed. According to the merchant, the meteorite must have fallen to the north, where the Tunguska River drains into a large waterway, deep in the Siberian wilderness.

Leonid is delighted to finally find someone who can indicate the meteorite's potential location. But his joy turns to resignation when he realizes the site is too far from the region’s railways, making it impossible for him to reach. After two years spent exploring Siberia, Leonid has no choice but to return to Petrograd empty-handed.

But Leonid refuses to give up on his dream of locating the meteorite he’s sure is still out there. So, five years later, he returns to Siberia, better prepared to explore the wilderness. Using horses, reindeer, and local guides, he treks through forests, until he reaches the trading post where the merchant saw the mysterious explosion of light. Then, he ventures even farther north, far past any houses or signs of civilization. And there, in the middle of the Siberian wilderness, a vast area of flattened and burned forestland comes into view.

As Leonid spots the site, he eagerly pushes forward, but his local guides come to a halt, refusing to enter this zone of destruction. They worry that the Tunguska Event was a curse laid down by a god and that entering the leveled forest will bring divine retribution. Undeterred, Leonid continues on alone, encountering thousands of uprooted, charred trees—all pointing in the same southward direction. Further on, he discovers some trees still standing upright — but they’re all dead and oddly stripped of their branches.

The peculiar nature of the devastation convinces Leonid that he has reached ground zero—the exact point where the Tunguska meteorite struck the Earth. He surmises that the shockwave was so intense that it stripped the trees of their branches with such speed that no strain was transferred to the trunks. The sheer size of the affected area also suggests an enormous impact, surpassing any meteorite he'd studied before, making it possibly the largest known to strike Earth.

But one thing still puzzles Leonid. He cannot find an impact crater. Instead, the swampy soil is pockmarked with deep holes. Leonid concludes that the meteorite must have shattered in the atmosphere, falling to the ground in fragments that caused these holes rather than a single, massive crater.

With these findings, Leonid will return to Petrograd confident that he has located the correct meteorite strike site. But he still won’t have any tangible evidence to carry with him. While he may have found the meteorite’s location, he will be unable to excavate the area on his own, forcing Leonid to return to Siberia once more, with a new party of people determined to dig for answers.

Act Two

It’s spring 1928, in Siberia, one year after Leonid Kulik discovered the likely epicenter of the Tunguska Event.

Leonid is on his way back to the possible impact site, only this time he has a group of laborers with him. The journey is still arduous. The laborers have to carry enough rations to support the group for weeks in the wilderness. Next to them, reindeer pull sledges packed with the group’s shovels, pickaxes, and other excavation tools. But Leonid is confident that all their discomfort and hard work will soon pay off.

In time, the expedition reaches the stretch of flattened forest where they immediately get to work, searching the waterlogged ground and its pockmark holes for any remnants of a meteorite.

They dig and dig until finally a shout catches Leonid's attention. He rushes to a hole where a worker grins, having struck a hard object with his shovel which he suspects is the meteorite. Excitement fills the air as the two men carefully excavate the find. But when the dirt is cleaned off, Leonid’s heart sinks. It's not a meteorite. It’s just the stump of an enormous dead tree.

With this discovery, Leonid starts to second-guess his theory. Perhaps meteorite fragments were not responsible for the holes on the forest floor after all. From the looks of it, the stump they excavated caused one of the holes itself, perhaps by gradually sinking into the swamp.

Disheartened but still determined, Leonid’s team spends the next few weeks excavating other holes. But their confidence in this meteorite theory continues to erode as they discover more ancient tree stumps at the bottom of each one. Still, Leonid insists no stone remains unturned. He bores the ground with hand augers; he sweeps across the site with sensitive magnets; he conducts a painstaking survey to identify any depressions that might mark an impact site. But there’s nothing out of the ordinary. 

When summer arrives and clouds of mosquitoes make further investigations impossible, Leonid once again retreats to Petrograd empty-handed. Nevertheless, his photographs of the devastated forestland cause a sensation in the Soviet scientific community. The scale of destruction is enough to persuade many previously skeptical scientists to agree that the Tunguska Event was indeed a meteorite strike. Encouraged by his colleagues, Leonid is urged to return to Siberia and solve the mystery once and for all.

Eight years after his second expedition, Leonid embarks on a new plan. He knows he has exhausted all avenues of searching for the meteorite on the ground, but he hasn’t yet tried to inspect the area by air. So, in the spring of 1937, Leonid takes off in an airplane to survey the site from above.

For two years, he conducts various trips observing the land, and what he sees amazes him. Only from the air can Leonid really take in the extent of the devastation. The total affected area covers 800 square miles, and he estimates that eighty million trees were destroyed. The aerial perspective also reveals astonishing patterns — the uprooted trees form an elliptical shape, while the trees fallen all align radially, pointing away from a central area where the branchless trees stand upright. This odd nature of the damage erases any doubts in Leonid's mind. He’s sure that the Tunguska Event was a meteorite strike—and he’s certain this is where it landed.

But the meteorite itself remains elusive. Leonid never finds any trace of the space rock he thinks hit Earth. His ambitions and expeditions are cut short by the outbreak of World War II. When the fighting begins, Leonid volunteers for the Soviet Army and then dies in a Nazi prisoner-of-war camp. But his two-decade inquiry into the Tunguska Event will not be lost. Despite his untimely death, Leonid’s scientific records endure and the investigation into the incident continues.

After the war, the space race begins. And as the USSR starts sending up satellites and cosmonauts, the Soviets’ understanding of space advances. Among their scientists’ new discoveries is the revelation that meteors falling into the Earth’s atmosphere sometimes explode in the sky, disintegrating as they burn up — a phenomenon known as an airburst.

This information will align with Leonid's theory about the Tunguska Event and help explain why he struggled to locate a meteorite. But scientists will be unsure whether an explosion could occur on such a large scale. Without ever having observed such an airburst with modern scientific instruments, they will be unwilling to declare exactly what occurred in the skies above the Tunguska River.

But, decades after Leonid’s passing, new evidence will emerge, suggesting that the Tunguska Event was indeed a meteor airburst, and bringing an end to many scientists’ search for answers.

Act Three

It’s the morning of February 15th, 2013, in the Russian city of Chelyabinsk, 105 years after the Tunguska Event.

Inside her car, an office worker glances at her dashboard clock and curses, realizing she’s running late for work. But as she speeds toward her office, an odd sight captures her attention. She watches in awe, as a bright light arcs across the sky, before vanishing in a blinding flash that forces her to shut her eyes and slam on the brakes.

As her car screeches to a halt, a tremendous explosion rocks the ground, shaking her vehicle side to side. Once the shaking and rumbling stops, she slowly and cautiously exits her car as other drivers do the same, all in shock at what just occurred.

Scientists scramble to understand the event, and within an hour, the Russian Federal Space Agency announces that a meteor entered the Earth's atmosphere and exploded in an airburst. News of the incident spreads rapidly worldwide, capturing global attention.

Investigators later reveal that the meteor had a diameter of almost 60 feet and weighed 10,000 tons. They conclude that it exploded in the air, 18 miles above Siberia, causing extensive damage and injuring over a thousand people — though, fortunately, no one was killed.

The Chelyabinsk incident, as this explosion will come to be known, becomes the largest meteor airburst recorded by modern scientific instruments — and it proves that huge meteors can explode in the atmosphere.

With their detailed observations of the Chelyabinsk meteor, most scientists will acknowledge that the Tunguska Event was also a meteor airburst, but on an even greater scale. While the Chelyabinsk meteor created an explosion that was the equivalent of 500 kilotons of TNT, the Tunguska explosion is estimated to have been thirty times more powerful.

With the Chelyabinsk explosion, the mystery surrounding the Tunguska Event will seem solved, leading modern scientists to a long-awaited conclusion, born out of Leonid Kulik’s relentless efforts to investigate the peculiar phenomenon that unfolded in the Siberian skies on June 30th, 1908.

Outro

Next on History Daily. July 3rd, 2013. Following major demonstrations against his rule, Egypt’s first democratically elected president, Mohamed Morsi, is ousted by the nation’s military.

From Noiser and Airship, this is History Daily, hosted, edited, and executive produced by me, Lindsay Graham.

Audio editing by Christian Parraga.

Sound design by Katrina Zemrak.

Music by Lindsay Graham.

This episode is written and researched by Scott Reeves.

Executive Producers are Alexandra Currie-Buckner for Airship, and Pascal Hughes for Noiser.