Tunguska Event June 30, 1908 is it meteorite or UFO

The Tunguska blast, in a desolate part of Siberia, remains one of the 20th century's biggest scientific mysteries.On June 30, 1908, what is widely believed to be a meteorite exploded a few kilometers above the Tunguska river, in a blast that was felt hundreds of kilometers (miles) away and devastated over 2,000 square kilometers of Siberian forest. If you look at the pictures from this explosion, it is evident how big this meteorite really was. It had a pretty big punch in it.

Witnesses in the town of Kirensk and nearby towns at the same distance recollected the fireball flashing across the sky in the following terms:

1. "I was sitting on the porch of the house at the trading station, looking north. Suddenly in the north...the sky was split in two, and high above the forest the whole northern part of the sky appeared covered with fire. I felt a great heat, as if my shirt had caught fire... At that moment there was a bang in the sky, and a mighty crash... I was thrown twenty feet from the porch and lost consciousness for a moment.... The crash was followed by a noise like stones falling from the sky, or guns firing. The earth trembled.... At the moment when the sky opened, a hot wind, as if from a cannon, blew past the huts from the north. It damaged the onion plants. Later, we found that many panes in the windows had been blown out and the iron hasp in the barn door had been broken."
2. "A ball of fire...coming down obliquely. A few minutes later [we heard] separate deafening crash like peals of thunder...followed by eight loud bangs like gunshots."
3. "A ball of fire appeared in the sky... As it approached the ground, it took on a flattened shape..."
4. "A flying star with a fiery tail; its tail disappeared into the air."

Because the object exploded up in the atmosphere, instead of hitting the ground, it left no crater. The effect on the ground was limited to devastation of a large forest area. At ground zero, tree branches were stripped, leaving trunks standing up. But at distances from roughly 3 out to 10 miles, the trees were blown over, lying with tops pointed away from the blast. No one was known to have been this close to the blast. The closest humans were probably herders camped in tents roughly 30 km from ground zero. They related:

"Early in the morning when everyone was asleep in the tent, it was blown up in the air along with its occupants. Some lost consciousness. When they regained consciousness, they heard a great deal of noise and saw the forest burning around them, much of it devastated."

"The ground shook and incredibly prolonged roaring was heard. Everything round about was shrouded in smoke and fog from burning, falling trees. Eventually the noise died away and the wind dropped, but the forest went on burning. Many reindeer rushed away and were lost."

One older man at about this distance was reportedly blown about forty feet into a tree, causing a compound fracture of his arm, and he soon died. Hundreds of the herders' reindeer, in the general area around ground zero, were killed. Many campsites and storage huts scattered in the area were destroyed. During a workshop of the International Association for the Astronomical Arts, I painted this view at Mt. St. Helens, Washington, where the devastated area bears an uncanny resemblance to the photos of the explosion site. At both the Siberian site and Mt. St. Helens are vistas where one sees nothing but felled trees, mile after mile, across distant hillsides. The transient heat flash from the fireball was felt by the witnesses at Vanavara, and apparently within about 30 km it was strong enough to ignite small temporary fires in the forest and singe tree bark. I based the view of the cloud in the sky on the distant reports of a ashy-colored cloud of smoke forming at the site of the blast; it was probably augmented some minutes later by smoke from the burning forest. Streamers of smoke from fragmented material would soon dissipate in air currents.

there are several Speculative hypotheses

Natural H-bomb

In 1989, the astronomers D'Alessio and Harms suggested that some of the deuterium in a comet entering the Earth's atmosphere may have undergone a nuclear fusion reaction, leaving a distinctive signature in the form of carbon-14. They concluded that the release of nuclear energy may have been almost negligible

Black hole

In 1973, Albert A. Jackson and Michael P. Ryan, physicists at the University of Texas, proposed that the Tunguska event was caused by a "small" (around 10²⁰ g to 10²² g) black hole passing through the Earth. Unfortunately for this hypothesis, there is no evidence for a so-called "exit event" — a second explosion occurring as the black hole, having tunneled through the Earth, shot out the other side on its way back into space — and it has not gained acceptance in the scientific community. This hypothesis was used by Larry Niven in his science fiction story The Borderland of Sol, and by David Brin, in Earth.

Antimatter

In 1965, Cowan, Atluri, and Libby that the Tunguska event was caused by the annihilation of a chunk of antimatter falling from space. However, as with the other hypotheses described in this section, this does not account for the mineral debris left in the area of the explosion. Furthermore, there is no astronomical evidence for the existence of such chunks of antimatter in our region of the universe. If such objects existed, they should be constantly producing energetic gamma rays due to annihilation against the interstellar medium, but such gamma rays have not been observed.

UFO crash

UFO aficionados have long claimed that the Tunguska event is the result of an exploding alien spaceship or even an alien weapon going off to "save the Earth from an imminent threat". This hypothesis appears to originate from a science fiction story penned by Soviet engineer Alexander Kazantsev in 1946, in which a nuclear-powered Martian spaceship, seeking fresh water from Lake Baikal, blew up in mid-air. This story was inspired by Kazantsev's visit to Hiroshima in late 1945.

Many events in Kazantsev's tale were subsequently confused with the actual occurrences at Tunguska. The nuclear-powered UFO hypothesis was adopted by TV drama critics Thomas Atkins and John Baxter in their book The Fire Came By (1976). The 1998 television series The Secret KGB UFO Files (Phenomenon: The Lost Archives), broadcast on Turner Network Television, referred to the Tunguska event as "the Russian Roswell" and claimed that crashed UFO debris had been recovered from the site. In 2004,

The Wardenclyffe Tower

Oliver Nichelson has suggested that the Tunguska explosion may have been the result of an experiment by Nikola Tesla using the Wardenclyffe Tower, performed during one of Robert Peary's North Pole expeditions

Recently Russian scientists said they have discovered the wreck of an alien device at the site of an unexplained explosion in Siberia almost a hundred years ago, China Daily reported today, citing the Interfax news agency as the source.The scientists, who belong to the Tunguska space phenomenon public state fund, said they found the remains of an extra-terrestrial device that allegedly crashed near the Tunguska river in Siberia in 1908.
Their findings also include a 50-kilogram (110-pound) rock which they have sent to the Siberian city of Krasnoyarsk for analysis.