Astronomy Chapter 6 Vocabulary

Seismograph

A device used to record and measure seismic waves, such as those produced by earthquakes

Rille

A winding crack or depression in the lunar surface caused by the collapse of a solidified lava tube

Solar wind

An outward flow of particles (mostly electrons and protons) from the Sun

Highlands

Heavily cratered, mountainous regions of the lunar surface

Coronal mass ejection

Large volumes of the high-energy gas released from the Sun's corona

Mare (maria)

Latin for "sea"; a large relatively crater-free plain on the Moon

Northern lights (aurora borealis)

Light radiated by atoms and ions in Earth's upper atmosphere due to high-energy particles from the Sun and seen mostly in the northern polar regions

Spring tide

The greatest daily difference between high tide and low tide, occurring when the Moon is new or full

Ionosphere (thermosphere)

Region of Earth's atmosphere, above the mesosphere, in which sunlight ionizes many atoms

Core

The central portion of an astronomical object

Core (of the Earth)

The central solid iron region and the liquid iron region surrounding it inside the Earth

Synchronous rotation

The condition when a moon's radiation rate and revolution rate are equal or when a planet's rotation rate equals its moon's revolution rate

Dynamo theory

The generation of a magnetic field by circulating electric charges

Continental drift

The gradual movement of the continents over the surface of Earth due to plate tectonics

Capture theory

The idea that the Moon was created at a different location in the solar system and subsequently captured by Earth's gravity

Mesosphere

The layer in Earth's atmosphere above the stratosphere

Neap tide

The least change from high to low tide during the day; it occurs during the first and third quarter phases of the Moon

Troposphere

The lowest level of Earth's atmosphere

Ozone layer

The lowest stratosphere, where most of the ozone in the air exists

Plate tectonics

The motions of large segments (plates) of Earth's surface caused by convection motions in the underlying mantle

Mantel

The portion of a terrestrial planet located between its crust and core

Regolith

The powdery, lifeless material on the surface of a moon or planet

Planetary differentiation

The process early in the life of each planet whereby denser elements sank inward and lighter ones rose

Seafloor spreading

The process whereby magma upwelling along rifts in the ocean floor causes adjacent segments of Earth's crust to separate

Magnetopshere

The region surrounding the earth or another astronomical body in which its magnetic field is the predominant effective magnetic field

Ejecta blanket

The ring of material surrounding a crater that was ejected during the crater-forming impact

Stratosphere

The second layer in Earth's atmosphere, directly above the troposphere

Crust

The solid surface layer of some astronomical bodies, including the terrestrial planets, the moons, the asteroids, and some stellar remnants

Cocreation theory

The theory that the Moon formed simultaneously with Earth and in orbit around it

Collision-ejection theory

The theory that the Moon was created by the impact of a planet-sized object with Earth; presently considered the most plausible theory of the Moon's formation

Tidal force

The tidal force is a secondary effect of the force of gravity and is responsible for the tides. It arises because the gravitational force exerted by one body on another is not constant across it; the nearest side is attracted more strongly than the farthest side.

Convection

The transfer of energy by moving currents of fluid or gas containing that energy

Van Allen radiation belts

Two flattened, doughnut-shaped regions around Earth where many charged particles (mostly protons and electrons) are trapped by Earth's magnetic field

Seismic waves

Vibrations traveling through or around an astronomical body usually associated with earthquake-like phenomena