Key Vocabulary

Adapation
Adjustment to changing environmental conditions.

Asteroid
Object found in the solar system, usually in the asteroid belt between Mars and Jupiter, that is made of rock and metal.

Aurora
Arches of light appearing in the upper atmosphere of a planet’s magnetic polar regions. Auroras are caused by the emission of light from excited atoms accelerated along the planet’s magnetic field lines.

Caldera
A large crater caused by the violent explosion of a volcano that collapses into a depression.

Comet
Object found in the solar system with a solid nucleus of ice and rock, and a tail of gas and dust that stretches millions of miles. A comet nucleus can be several miles across and is made chiefly of ammonia, methane, carbon dioxide and water.

Cretaceous Period
A time period that occurred 146-65 million years ago and ended with the KT event, which marked the extinction of the dinosaurs and many other species.

Cretaceous-Tertiary Event
Also known as the KT event (K because chalk in Greek begins with a K); the mass extinction believed to have cause the extinction of the dinosaurs.

Electromagnetic Pulse
Intense electromagnetic radiation that disrupts electronic and electrical systems.

Extinction
What happens when the very last member of a species dies.

Fossil Record
Term used to refer to all fossils that have been discovered and the information gained from them.

Geologic Record
The history of Earth recorded in rock layers.

Hypernova
An extremely large, fast-burning star which is likely to end in self explosion.

Impact Theory
Idea that a collision from and asteroid or comet caused the mass extinction known as the KT event.

Iridium
A rare chemical that is found in the center of Earth or an asteroid or comet; its presence is interpreted to be evidence of the KT event indicating an asteroid or comet as the cause. It is number 77 on the periodic table.

Magnetic Field
The portion of space near a magnet in which the magnetic forces (due to the region) can be detected.

Meteor
Any small particle of matter in the solar system that is directly observable by the light they give off upon entering the atmosphere.

Ozone Layer
An atmospheric layer that has a high level of ozone and blocks most solar ultraviolet radiation from entering the lower atmosphere.

Paleontologist
A person in the field of paleontology; a person who studies species of the past and the geological periods based on fossil remains.

Photosynthesis
The process by which organisms (primarily plants) produce a food source of sugar and carbon dioxide from sunlight and water.

Radiation
The process of emitting energy in the form of waves or particles.

Supervolcano
Volcano that produces the largest and greatest volume of eruptive material; the eruption radically alters landscape and climate.

Species
A class of individuals having common attributes and designated by a common name; a category of biological classification capable of interbreeding.

Tertiary Period
Time period that lasted from 65 to 1.8 million years ago; time period following the Cretaceous period and the KT event.

Tsunami
An unusually large wave produced by tectonic plate movement or volcanic eruption.