Asteroid

An asteroid of the size of the one that hit Yucatan in 65 million B.C.E. may impact Earth in 2012 as it passes close by. Tunguska was the 1908 explosion of a stony asteroid or comet over Siberia, which leveled several thousand square miles of forrest. The explosion equaled 100s of Heroshima-sized bombs. : )

If that happens we will all sleep with the dinosaurs.

Don’t simply refer me sites like Wikipedia… I’ve read nearly everything online about the incident.

I would rather hear what you have to say about it. Do you buy into the asteroid or comet theory? Do you believe one of the other theries? Do you have your own theory?

there is good evidence it was a meteor.

most of it was vaporised before hitting the ground, which is why it was easy for some people to make up weird stories about it. Black hole, spaceship, you name it.

a meteorite can explain everything that happened, and is by far more likely than any of the other scenarios.

Over the years I have come across several accounts of the incident. Each represented the prevailing scientific opinion as the object being a small comet. This explanation has always made more sense to me. Why do scientists now think it was a more solid object? Or do they?
Crabby blindguy, thanks for the answer. Your comments made me wonder: mateorites or asteroids may have formed by two or more different methods. Meteorites, as we know, are solid, rocky bodies. But there may be some objects whic accreted like the earth did. Because of their tiny size, they never fully solidified and they might be loose aggregates of dust and gravel-sized particles. Think maybe?
Okay gleemonex69, a small, sudden appearance of antimatter could cause such an event. Now what’s the evidence for it. Matter-antimatter annihilation creates gamma rays. Is there any evidence of gamma ray radiation in the area?

There’s no complete consensus. However, the idea is partly a result of the fact that some traces of metallic compounds were found tha tappear to have come from whatever it was–and that would be unusual for a cometary fragment. Also, we knnow that a solid objject can usperheat enough to explode–as well as a comet. And one thing is clear is that whatever the composition f the Tunguska object, it did explode in the air, rather than strike the ground as a intact body.

Maybe when we get a chance to send spacecraft to some of the near-Earth asteroids and study them we’ll be able to come up with a definitive answer. Which may be as early as the next decade!

According to this article in Scientific American ( http://www.sciam.com/article.cfm?id=the-tunguska-mystery-100-years-later ), scientists DO NOT think it was caused by a large meteoroid. They think it was caused by a either a comet or an asteroid.

The difference between a comet and a rocky asteroid at Tunguska would have been slight. Either one would explode before reaching the surface (the comet at a slightly higher altitude, perhaps). Various theories have been proposed regarding the exact nature of the impactor, including antimatter and a quantum black hole. The latest evidence to suggest an asteroid as the impactor is Lake Cheko, near the blast epicenter. Studies indicate that it has a conical bottom profile (other lakes in the region have flat bottoms) with an unusual density buried beneath the center of the lake (see link). The suspicion is that the lake is an impact crater left by a small fragment of the asteroid, which is now buried at the bottom. Further studies are under way and should determine the nature of the lake and whatever lies underneath it.