Tunguska, 1908

The largest impact event in recorded history, and it left no crater.

Key facts

When

30 June 1908, a little after 7 in the morning local time

Where

Near the Podkamennaya Tunguska river, Siberia, Russia

What hit

a stony asteroid or a piece of comet, probably about 40 to 60 m across

Era

Witnessed, 1908 to 1999

Location

60.89° N, 101.90° E

What happened

On the morning of 30 June 1908 people across central Siberia saw a brilliant fireball cross the sky, followed by a flash and a blast. At the trading post of Vanavara, about 65 km away, a man sitting on a porch was thrown from his chair and felt heat as if his shirt were on fire.

The object exploded in the air. The blast flattened about 80 million trees over about 2,150 km² of forest, an area larger than Greater London, laying them out in a radial pattern pointing away from the centre. Near the centre, trees were left standing but stripped of their branches. Reindeer were killed and a few people may have died, but the area was so remote that the human toll was tiny.

The first scientific expedition, led by Leonid Kulik, did not reach the site until 1927. He expected a crater and a giant meteorite, and found neither.

Effects

Pressure waves were recorded by barometers as far away as Britain, and seismic stations picked up the shock. For several nights afterwards the skies over Europe and Asia were so bright that people could read outdoors at midnight, probably because of dust and ice high in the atmosphere.

The evidence

The pattern of fallen trees, which points back to the blast centre; tiny melted spherules and traces of meteoritic elements in soil and tree resin; eyewitness accounts; and the instrument records. Whether the object was a stony asteroid or a comet fragment is still debated, and so is a proposal that nearby Lake Cheko is a crater left by a surviving fragment.

Did you know?

Related pages

How is impact energy measured? See energy explained, or try the impact calculator.