6 In the ancient Greek city of Hierapolis, there was a Gate to Hell where animals were led for sacrifice. Inside the cave, animals died without any human intervention. It was believed that the breath of Pluto killed them. However, in 2018, archaeologists found that the deaths were a result of a 91% concentration of CO₂ in the air, created by volcanic activity underneath the cave.

The ancient Greek historian, Strabo, recorded a strange ritual he witnessed at the Plutonium in the ancient Greek city of Hierapolis, 2,000 years ago. There, beneath the stone seating of the Plutonium, was a Gate to Hell.

Castrated priests would lead healthy bulls into the gate for sacrifice. Once inside, the animal died quickly without any human intervention and the priests would return unscathed. The breath of Pluto was credited for the killing of the animals

With the rediscovery of Plutonium in 2011, archaeologists have looked elsewhere for an explanation instead of Pluto. Named after the underworld god, Pluto, the Plutonium sat directly above a deep fissure that emitted volcanic carbon dioxide.

Testing of the air inside the Gate revealed a toxic level of 91% of CO₂ in the air, enough to kill both humans and animals.

However, as CO₂ is heavier than oxygen, it is heavily concentrated near the floor and dissipates with height. This explains the returning of the priests unharmed. They were tall enough to keep their heads above the concentrated gas. (1, 2)

7 In August 1972, around 4,000 US mines exploded in the seas bordering North Vietnam without any apparent triggers. Forty-six years after the incident, a research team discovered that flares from a very powerful solar storm had triggered the magnetic sensors of the mines causing them to explode.

During the Vietnam war, the US forces had dropped mines in the seas bordering northern Vietnam. In the first few weeks of August 1972, around 4,000 mines detonated without being triggered by any apparent reason. Pilots flying over the area reported seeing around two dozen mines exploding within 30 seconds.

The Navy investigated the bizarre phenomena, but the report got buried with other files.

Forty-six years later, in 2018, researchers investigating a 1972 solar storm dug into Naval documents to check the reports on the unexplained detonation of the mines.

They discovered that a powerful solar storm that had hit the Earth during the same period was responsible for the explosion. Fiery, solar flares reaching the Earth in just under 15 hours had distorted the Earth’s magnetic field. This triggered the magnetic sensors in the mines, causing them to explode. (1, 2)

8 The sudden collapse of the Mayan Civilization from the late eighth century through the end of the ninth century had baffled many. Since 2005, archaeologists excavating in northern Guatemala developed a precise chronology using 154 radiocarbon dates to find that intensification of warfare led to social instability, followed by the fall of the Maya lowlands.

One of the best-known civilizations of old is the Mayan Civilization. Originating around 2,600 BCE, the Mayan Civilization was situated in present-day southern Mexico and surrounding areas. Very advanced for their times, the Mayans were masters in archaeology, hieroglyphic writings, farming, and astronomy. However, civilization suddenly collapsed around the ninth century.

The exact cause of the collapse is largely discussed among researchers and archaeologists. The exploitation of land, overpopulation, and severe degradation of the environment are some cited theories. In the 21st century, severe drought became a popular theory explaining the collapse.

While there is no universally accepted theory, intense archaeological investigations at the Ceibal site in northern Guatemala have allowed researchers to develop a high-resolution chronology using 154 radiocarbon dates. They concluded that intensification of warfare resulted in political turmoil and social instability. This led to the fall and eventual abandonment of the Mayan centers across the lowlands. (1, 2)

9 On June 30, 1908, The Tunguska Blast destroyed 830 square miles of land in remote Siberia. Locals believed it to be a cursed visit from their god, Odgy. However, damage assessments and geological studies conducted in later years established that the explosion had been a result of a meteor or an asteroid entering Earth’s atmosphere and bursting in air, just before impact. 

June 30, 1908, witnessed an unnatural explosion that reduced 830 square miles of land in a remote region in Siberia to dust. Occurring near the Podkamennaya Tunguska River in remote Siberia, the blast was so powerful that it broke windows hundreds of miles away.

The emanating heat was felt as far as 40 miles away. Eighty million trees are estimated to be destroyed, along with wildlife. Locals believed that their god, Odgy, had displayed wrath on the people by destroying trees and wildlife.

The first scientific expedition to the area was in 1921 when Leonid Alekseyevich Kulik led an expedition to Tunguska. Leonid Kulik was the chief curator for the meteorite collection of the St. Petersburg museum. He suggested that the blast was from a giant meteorite impact.

In recent times, NASA explained that “a stony asteroid the size of a five-story building broke apart 15 miles above the ground.” This is also the reason why there is no impact crater on the location. The asteroid traveled at 33,500 miles per hour and weighed 220 million pounds. (1, 2)

10 H.M.S. Erebus and H.M.S. Terror were two sister ships that disappeared in 1848. The ships were a part of the Franklin Expedition set out to search for the Northwest Passage. Many search expeditions over the centuries failed to locate the ships or the crew. It took until 2014 for a Canadian mission to discover Erebus, and two more years to discover Terror on the ocean floor.

Sir John Franklin led the quest for one of the biggest discoveries of the time: the Northwest Passage, a long-sought pathway from Atlantic to Pacific through Canada’s Arctic inlets.

Along with 127 other men, he sailed the H.M.S. Erebus and H.M.S. Terror on the three-century-old quest. However, both ships vanished without a trace. Scores of rescue expeditions over the centuries never found the ship or the men

Finally, in September 2014, a search team found Erebus at the eastern part of Queen Maud Gulf, just 36 feet deep in the water. Its sister ship, Terror, was found two years later by the Arctic Research Foundation Expedition in 79 feet of water in Terror Bay.

The wreckage of the Terror was still in an unexpectedly intact condition. (1, 2)