At 7.14 a.m. on June 30, 1908, a huge fireball exploded in the Siberian sky. A thousand times the force of the Hiroshima atomic bomb, it flattened an area of remote Tunguska forest bigger than metropolitan New York, forming a mushroom cloud that almost reached into space.

What was it? A wayward black hole, a crashing comet, a rogue asteroid, an exotic rock of antimatter or mirror matter, a methane gas blast from below, an alien spacecraft, a laser beam fired by extraterrestrials, or an early experiment in nuclear physics which got out of hand?

More than a century on, this grand dame of science mysteries still fascinates scientists and charlatans alike.

Australian science journalist and author Surendra Verma tells the incredible story of this famous fireball. He also examines the major theories – scientific and fanciful – and evaluates the new evidence that claims that the mystery has at last been 'solved.' Or, is it?

First published in 2005, this ebook is an completely revised and updated 2021 edition.