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Earth Science Chapter 4


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What evidence is there that the earth is a spheroid?
Pictures taken from space.
What is a spheroid? How was it formed?
A sphere with a bulge in a center. It was formed by the fast spinning of the young Earth.
Describe the Earth's layers starting with the crust and moving inward.
crust (solid), mantle (solid with liquid qualities, inner core (solid), outer core (liquid)
What are the lithosphere and aesthenesphere?
They are near the surface. The lithosphere is rigid and floats on the aesthenisphere which is slushy.
What are the sources of the earth's heat?
1)meteorite impacts 2) decaying of radioactive isotopes, 3)pressure from the earth's outer layers on the inner layers.
Is the Earth gaining or losing heat? At what rate?
Losing. The rate varies depending on the type of rock, the thickness of the crust in that place, the amount of radioactive material in the rock.
At what rate does the earth get hotter as you go toward the core?
1 degree C. for every 40 meters.
What are the earth's magnetic poles and why are they called this?
A magnetic field is the lines of force between positive and negatively charged poles.(like a battery). On Earth, these magnetic poles are actually a short distance from the geographic N and S poles.
What are two pieces of evidence that the earth rotates?
Foucault's Pendulum and the wind (the Coriolis effect)
How did Foucault's Pendulum demonstrate that the earth rotates?
The direction of swing changed 11 degrees in an hour and we knew that pendulums never change the direction of their swing so earth must be moving.
What is the Coriolis effect?
Winds don't blow straight. They are deflected to the right in the N. hemisphere and the left in the S. hemisphere.
Why is the speed of the Earth's rotation higher at the Equator than at the Poles?
Because the circle around the Equator is bigger than at the poles so it has to spin faster to stay in line with the poles.
How are time zones determined?
They divided the Earth into 24 zones (one per hour). Each was 15 degrees wide. They made the Prime Meridian noon and 0 degrees, and then counted one hour each way. Going east, you subtract one hour for every 15 degrees. Going west, you add one hour for every 15 degrees.
Why does it get dark a little earlier on the eastern side of the time zone?
Because the earth rotates and so the sun appears earlier in the eastern side of a time zone and disappears earlier.
What evidence is there for the Earth's revolution around the sun?
Parallax, which is when the stars APPEAR to move toward or away from each other at different times of year. Actually the Earth is moving.
What is an ellipse?
an ellipse is an oval shape
What effect does revolving in an ellipse instead of a circle have on our distance from the sun? What is the perihelion and the aphelion?
the Earth is closer (perihelion) or farther (aphelion) from the Earth depending on where it is on the ellipse.
Why do we have winter and summer?
Because the northern hemisphere is tilted away from the sun durring winter, making it colder. durring summer it is tilted towards the sun so it is warmer and we have summer.
What is the summer solstice? What is the winter solstice?
the summer solstice is the point at which the daily increase stops. at summer solstice, the northern hemisphere is the closest it gets to the sun. so we have the longest day of the year.
the winter solstice is when the sun follows the shortest possible route and we have the shortest day of the year because the sun is out for the shortest amount of time.
What is the vernal equinox? What is the autumnal equinox? How is the earth tilted with respect to the sun?
the autumnal equinox is when the sun is overhead at the equator at noon. each of earth's hemispheres receives equal amount of sunlight

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