25 terms

# Chapter 4, Earths Structure and Motion

This set is designed to help the students practice the Chapter 4 vocabulary terms.
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oblate spheroid
The shape of the Earth, which is a sphere that bulges in the center.
inner core
The Earth's center, which is composed of solid iron and nickel.
outer core
The layer of liquid iron and nickel that is directly above the inner core.
mantle
The thickest of Earth's layers, which is directly above the outer core. It is composed mostly of compounds rich in iron, silicon, and magnesium.
lithosphere
The crust and the uppermost portion of the mantle.
asthenosphere
A thin, slush like layer of the mantle that the more rigid material of the lithosphere floats upon.
magnetic field
The lines of magnetic force that surround the Earth and protect it from the sun's deadly solar wind.
rotation
The spinning of the Earth on its axis.
Foucault pendulum
An iron sphere on a very long wire, that gives evidence that the Earth rotates on its axis.
Coriolis effect
The apparent deflection of the winds caused by the spinning of the
Earth on its axis.
time meridian
Each standard time zone which is roughly centered on a line of longitude exactly divisible by 15º.
prime meridian
An arbitrary longitude line which is the starting point for the standard time zones.
International Date Line
An imaginary line that represents the longitude at which the date changes.
revolution
The movement of the Earth in its orbit around the sun.
parallax
The apparent shift in positions of nearby stars compared to distant stars. This is evidence of the Earth's revolution around the sun.
summer solstice
The day in which we have maximum daylight. In the Northern Hemisphere this happens around June 21.
winter solstice
The day in which we have the least amount of daylight. In the Northern Hemisphere this happens around December 21.
vernal equinox
The day in March when there are 12 hours of daylight and 12 hours of night.
autumnal equinox
The day in September when there are 12 hours of daylight and 12 hours of night.
perihelion
The point in the Earth's orbit in which the Earth is closest to the Sun.
aphelion
The point in the Earth's orbit in which the Earth is farthest from the Sun.
Arctic Circle
The latitude line that is 23.5º below the North Pole. Areas above this line have 24 hours of darkness on Dec. 21st
Antarctic Circle
The latitude line that is 23.5º above the South Pole. Areas below this line have 24 hours of darkness on June 21st
Tropic of Cancer
The latitude line that is 23.5º above the equator. Areas on this line have the sun directly overhead on June 21st.
Tropic of Capricorn
The latitude line that is 23.5º below the equator. Areas on this line have the sun directly overhead on Dec 21st.