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On June 30, 1908, a meteor exploded near the remote Podkamennaya Tunguska River in Siberia, Russia. As of 2014, the Tunguska Event is the largest “impact event” in recorded history.
 
Astronomers and meteorologists have studied the Tunguska Event using mathematical models, expeditions to Siberia, eyewitness accounts, and sediment cores from peat bogs in the Tunguska region. Using these resources, scientists have a pretty good idea about what happened during the Tunguska Event.
 
A 100-million kilogram (220 million-pound) space rock crashed through Earth’s atmosphere at about 54,000 kilometers per hour (33,500 miles per hour). As it sped through the atmosphere, the rock heated to a scorching 25,000 degrees Celsius (44,500 degrees Fahrenheit). About 6-10 kilometers (4-6 miles) above the Tunguska region, the rock exploded. The enormous explosion immediately felled 80 million trees, and caused a shock wave that shook houses 65 kilometers (40 miles) away.
 
So, although the Tunguska Event is usually classified as an “impact,” the meteor actually exploded before it ever hit the ground.
astronomer
Noun

person who studies space and the universe beyond Earth's atmosphere.

Noun

layers of gases surrounding a planet or other celestial body.

Noun

wetland of soft ground mostly made of partially decayed plant matter called peat.

damage
Noun

harm that reduces usefulness or value.

enormous
Adjective

very large.

expedition
Noun

journey with a specific purpose, such as exploration.

explosion
Noun

violent outburst; rejection, usually of gases or fuel

forest
Noun

ecosystem filled with trees and underbrush.

Noun

rocky debris from space that enters Earth's atmosphere. Also called a shooting star or falling star.

meteorologist
Noun

person who studies patterns and changes in Earth's atmosphere.

model, computational
Noun

a mathematical model that requires extensive computational resources to study the behavior of a complex system by computer simulation.

peat
Noun

layers of partially decayed organic material found in some wetlands. Peat can be dried and burned as fuel.

Noun

any area on Earth with one or more common characteristics. Regions are the basic units of geography.

remote
Adjective

distant or far away.

scorching
Adjective

very hot.

sediment core
Noun

cylinder of accumulated sediment of a region, visible as layers.

shock wave
Noun

moving, measurable change in pressure and density of a material.