Target Tunguska

In 1993 NASA scientists Christopher Chyba and Kevin Zahnle and their colleague Paul Thomas from the University of Wisconsin gave the asteroid theory for the Tunguska explosion new weight and rigour. Their computer simulations to explain the pattern of trees blown down showed that the explosion released about 15 megatons of energy in the atmosphere at an altitude of about 8 kilometres, but did not crater the Earth's surface. They then examined the entry of three classes of asteroids (stony, iron...

The Tunguska black hole

When Jackson and Ryan proposed their impeccably scientific black hole theory, they commented that many attempts had been made to explain the Tunguska event, 'ranging from the prosaic to the bizarre', and then suggested that 'a black hole of substellar mass such as those that have been postulated by Hawking could explain many of the mysteries associated with the event'. Their explanation has never been called 'prosaic' or 'bizarre', but it has certainly been described as 'imaginative and...

Spaceship Tunguska

In August 1945, Little Boy and Fat Man changed our world forever. Curious names for two atomic bombs that unleashed untold devastation upon humanity. On 6 August, Little Boy almost wiped the city of Hiroshima from the map of Japan. Three days later, Fat Man exploded into history in the Nagasaki sky. 'It was hard to believe what we saw', said Colonel Paul Tibbets, the pilot of the B-29 plane that dropped the atomic bomb on Hiroshima, describing at a press conference what he saw seconds after the...

Not a cosmic vacuum cleaner

A black hole is a star that has stopped twinkling. But why An ordinary star is one of the simplest entities in nature it is a sphere of gas that is by mass 73 per cent hydrogen, 25 per cent helium and 2 per cent other elements. The temperature in the centre of a star is very high - high enough to fuse nuclei of hydrogen and helium together. The nuclear fusion produces energy that is radiated from the surface of the star as heat and light. The universe has ten times as many stars as grains of...

Zapped by a laser

Intelligent life on this planet in the form of two Russian science writers has suggested that Tunguska was mistakenly zapped by a laser sent by ETs from a giant planet orbiting the star 61 Cygni, about eleven light-years away from us. In a lengthy article published in the magazine Zvezda in 1964, Genrikh Altov and Valentina Zhurav-leva said that the violent volcanic eruption of Krakatoa in August 1883 generated strong radio waves. This signal was received eleven years later by Cygnian...

The first Tunguska expedition

Tunguska Expedition

In early February 1927 Kulik left Leningrad (as St Petersburg was again renamed in 1924) with one assistant named G.P. Gyulikh. Travelling by the Trans-Siberian Express, on 12 February he reached the remote Siberian station of Taishet, some 900 kilometres south of the Tunguska explosion site. After buying food and supplies and other equipment, Kulik and his assistant left Taishet by horse-drawn sledges. Battling frequent snowstorms and bitter temperatures, it took them five days to reach the...

A lesson in meteoritics and investing in metals

Today, more than 200 years after the publication of Chladni's 'infamous' book, we know that meteorites (from the Greek word meteoros, meaning 'high in the air') are chunks of extra-terrestrial matter, remnants of geological processes that formed our solar system 4,600 million years ago. When these chunks enter Earth's atmosphere they shine brightly because of the heat produced by friction with the air. Most chunks are too small - usually the size of a grain of sand, but no larger than a pea -...

Died of other causes

Some scientists believe that dinosaurs were not 'killed' their end was natural. The traditional favourite for the death of the dinosaurs has been the slow change in climate. The list of suspects for a slow climate change includes ice ages, collision of continents and the greenhouse effect. Dinosaurs and many other species were unable to adapt to the changes and therefore died. Mammals and some other species adapted and survived. Another traditional favourite is the drop in sea level. Large sea...

The comet did it

The scary scenarios of a comet striking Earth are hypothetical, but the devastated Siberian taiga is a reality. The Soviet Academy of Sciences was determined to find an answer, and in 1954 sent Kirill P. Florenskiy, a geochemist, to survey the Tunguska site. Using modern cartographic equipment, Florenskiy made an aerial survey of the region and drew up a new, more accurate map. In 1957 the Russian mineralogist A.A. Yavnel microscopically analysed soil samples brought back by...

Balls of ice and dust

Comets are fossils - frozen relics from the time of the infant Sun. By studying them, astronomers can find out how the Sun and the planets were born. In the early 1950s Fred Whipple and other astronomers provided an insight into the structure of comets. Whipple said that a typical comet has three parts a frozen central part called a nucleus, a fuzzy cloud surrounding the nucleus called a coma (or head), and a tail consisting of gas and dust. The nucleus, usually only a few kilometres across, is...

From antimatter to mirror matter

The idea of a 'mirror world' was first suggested in 1956 by Chinese-American physicists Chen Ning Yang and Tsung Dao Lee. First, a tiny dose of particle physics, before you can enter their 'mirror world'. The universe is held together by four types of fundamental forces - gravity, electromagnetism, the strong force, and the weak force - which are transmitted or 'mediated' by the exchange of elementary particles. The gravitational force, or gravity, is the long-range force responsible for the...

New centurys gift

On 1 January 1801, the first evening of the new century, Piazzi observed an unfamiliar point of light in the sky. He thought that the object might be a new star. Over the next three evenings he observed it again and noticed that it had shifted its position at the same rate as on the preceding days. Piazzi was now sure that it was not a fixed star. Thinking it might be a comet, he continued to follow it until 11 February when an illness cut short his work. However, on 24 January he announced his...

A giant lightning ball

A few years ago, a reader wrote to the 'Science Times' section of The New York Times about a lightning ball that was seen by her family to 'enter the glass front door, go right past us (or possibly even through us) in the living room and leave by the back window, where it hit a tree, causing some damage'. The Science Times commentator joked, 'Next time, take a picture', because it is one of nature's rarer phenomena and few photographs of it exist. It is also the least understood. Ball lightning...

Our man in Tunguska

The face that peers out from the 40-kopeck stamp released today by the USSR is that of a worried, bespectacled, grey-bearded man wearing a fur hat. The stamp commemorates the fiftieth anniversary of the Tunguska fireball and the scientist who devoted the last two decades of his life to solving the riddle of the mysterious Siberian meteorite. He was the first scientist to visit the Tunguska site. From 1927, when he led the first expedition to Tunguska, to his death...

A mini Tunguska

A small team of researchers and journalists from Irkutsk reached the remote area in late October 2002. But despite using satellite data to locate its position, they were unable to identify and reach the impact site latitude 58 degrees 9 minutes north, longitude 113 degrees 21 minutes east . The researchers collected 25 eyewitness accounts, which generally agreed that 'a large rock fell from the sky and then the earth trembled'. Some local residents as far away as 70 kilometres from impact site...

Antimatter Tunguska

In 1940, when the idea of anti-matter was nothing more than a mass of mathematical equations, the Russian scientist Vladimir Rojansky suggested the possibility of the existence in outer space of contraterrene meteorites contraterrene, CT, or its phonetic transcription Seetee are obsolete terms for anti-matter, and were once very popular in science fiction the ordinary matter was called terrene . Rojansky also said that such a meteorite 'would be entirely radiated away before reaching the...

The testimony of trees

Carbon atoms come in eight varieties, known as isotopes. Carbon-12 6 protons and 6 neutrons in the nucleus is the most common isotope. High-energy neutrons which continuously bombard Earth convert ordinary carbon-12 into radioactive carbon-14 6 protons and 8 neutrons . Living things go on absorbing carbon-12 and carbon-14 until the time of their death. In the case of trees, carbon-14 is recorded in annual growth rings, which also give the age of trees. It has been suggested that if the Tunguska...

The tongue of flame

The Siberian newspapers of the time were no better informed than their distant British and American counterparts, but the explosion was reported widely. In the Irkutsk newspaper Sibir on 15 July, a correspondent reported that on the morning of 30 June peasants in the village of Nizhne-Karelinskoye about 465 kilometres from the explosion site saw quite high above the horizon a body shining very brightly with a bluish-white light. The body was in the form of 'a pipe', and too bright for the naked...

The Incredible Journey of a Black Hole

Mini black holes are still very much a figment of scientists' imagination, but they provide such a neat and fitting explanation for the Tunguska event that this theory has become the part of the folklore now associated with the mysterious fireball. In 1973 the American theoretical physicists A.A. Jackson IV and Michael P. Ryan Jr said that, since 'no crater and no meteorite material that can unambiguously be associated with the event have ever been found', a mini black hole could explain the...