Chapter Terms 5 Flashcards
Surface gravity
The acceleration due to gravity at the surface of a star or planet.
Escape speed
The speed necessary for one object to escape the gravitational pull of another. Anything that moves away from a gravitational body with more than the escape speed will never return.
Mantle
Layer of Earth just interior to the crust.
Crust
Layer of Earth that contains the solid continents and the seafloor.
Hydrosphere
Layer of Earth that contains the liquid oceans and accounts for roughly 70 percent of Earth’s total surface area.
Atmosphere
Layer of gas confined close to a planet’s surface by the force of gravity.
Magnetosphere
A zone of charged particles trapped by a planet’s magnetic field, lying above the atmosphere.
Tides
Rising and falling motion of terrestrial bodies of water, exhibiting daily, monthly, and yearly cycles ocean tides on Earth are caused by competing gravitational pull of the moon and Sun on different parts of Earth
Tidal bulge
Elongation of Earth caused by the difference between the difference between the gravitational force on the side nearest the Moon and the force on the side farthest of the Moon. The long axis of tidal bulge points toward the Moon. More generally, the deformation of any body produced by the tidal effect of a nearby gravitational object.
Tital force
The variation in one body’s gravitational force from place to place across another body-for example, the variation of the Moon’s gravity across Earth.
Synchronous orbit
State of an object when its period of rotations is exactly equal to its average orbital period. The moon is in a synchronous orbit and so presents the same face toward Earth at all times.
Tidally locked
Condition in which tidal forces have caused a body (such as a moon) to rotate at exactly the same rate at which it orbit another body so that it always the same face toward the other body.
troposphere
The portion of Earth’s atmosphere from the surface to about 15 km
Stratosphere
The portion of Earth’s atmosphere lying about the troposphere, extending up to an altitude of 40-50 km.
Mesosphere
Region of Earth’s atmosphere lying between the stratosphere and the ionosphere, 50-80km above the Earth’s surface.
Ionosphere
Layer in earth’s atmosphere above 100km where the atmosphere is significantly ionized and conducts electricity.
Convection
Churning motion resulting from the constant upwelling of warm fluid and the concurrent downward flow of cooler material to take its place.
Convection cells
Circulating region of upwelling hot fluid and sinking cooler fluid in convection motion.
Ozone layer
Layer of Earth’s atmosphere at an altitude of 20-50 km where incoming ultraviolet solar radiation is absorbed by oxygen, ozone, and nitrogen in the atmosphere.
Greenhouse effect
The partial trapping of solar radiation by a planetary atmo-sphere, similar to the trapping of heat in a greenhouse.
Earthquake
A sudden dislocation of rocky material near Earth’s surface.
Seismic waves
A wave that travels outward from the site of an earthquake through Earth.
Outer core
The outermost part of Earth’s core, believed to be liquid and composed of nickel and iron.
Inner core
The central part of Earth’s core, believed to be solid and composed mainly of nickel and iron.
Volcano
Upwelding of hot lava from the below Earth’s crust to the planet’s surface.
Differentiation
Variation in the density and composition of a body, such as Earth, with low-density material on the surface and higher-density material in the core
Radioactivity
The release of energy by rare, heavy elements when their nuclei decay into lighter nuclei.
Maria
Relatively dark-colored and smooth refions on the surface of the Moon (singular: mare)
Highlands
Relatively light-colored regions on the surface of the Moon that are elevated several kilometers above the maria. Also called terrae
Craters
Bowl-shaped depression on the surface of the planet or moon, resulting from a collision with interplanetary debris
Van Allen belts
At least two doughnut-shaped regions of magnetically trapped, charged particles high above Earth’s atmosphere.
Aurora
Event that occurs when atmospheric molecules are excited by incoming charged particles from the solar wind, then emit energy as they fall back to their ground states. Aurorae generally occur at high latitudes, near the north and south magnetic poles.
Dynamo theory
Theory that explains planetary and stellar magnetic fields in terms of rotating, conducting material flowing in an object’s interior.
Core
The central region of Earth, surrounded by the mantle.
The central region of any planet or star.
Plate techonics
The motions of regions of Earth’s lithosphere, which drift with respect to one another. Also known as continental drift.
