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Astronomy 101-052: Earth: Chapter 6
Terms in this set (25)
The shifting of large blocks of the Earth's surface is usually referred to today as what?
What are the most common elements composing the Earth?
Oxygen and silicon.
About how hot is the core of the Earth?
The interior of the Earth is very hot because of _______.
the radioactive decay of elements
Why isn't the Earth a perfect sphere?
Rotation causes the equator to bulge out.
What does the Greenhouse Effect cause?
It causes the Earth's surface and atmosphere to be warmer than they would be otherwise.
What are the main constituents of the Earth's atmosphere?
Nitrogen and oxygen.
The ozone layer protects us from
On what plate of the crust is North America located? Which way is it moving?
North American; West.
What is happening when two plates are smashing into one another?
Subduction causes mountains to be built up; earthquakes and volcanoes may also occur.
How do we know the Earth has a liquid core?
P waves pass through it, but S waves do not.
Why is the inner core solid even though it is hotter than the outer liquid core?
The great pressure at Earth's center forces the atoms in the core together, causing it to solidify.
Currents in the Earth's molten iron core create the planet's magnetic field. These current are probably caused by
rotational motion and convection.
How are the auroras related to the Earth's magnetic field?
A) The Earth's magnetic field "channels" solar particles toward our poles, so that is where auroras are most common.
C) Solar particles directed into our atmosphere by the Earth's magnetic field excite atoms in our upper atmosphere. These atoms then emit light, which we see as auroras.
Both A and C
How is the age of the Earth measured?
By studying the ratios of radioactive materials in rocks.
Scientists think the Earth's core is composed mainly of
Our knowledge of the composition of the Earth's core comes from
analysis of earthquake waves.
The slow shifts of our planet's crust are believed to arise from
heat from the interior causing convective motion, which pushes on the crust.
If the shape of the Earth's orbit was unaltered but its rotation axis was shifted so that it had no tilt with respect to the orbit, seasons would be
essentially nonexistent, with little temperature change at a given place throughout the year.
What evidence indicates that part of the Earth's interior is liquid?
No S type of seismic waves are detectable at some locations after an earthquake.
Why do we believe the Earth has an iron core?
The properties of seismic waves match those expected of a region of iron.
What might explain how the core formed?
Iron sinking to the core as the bulk of the Earth melted.
Why is the core hot?
A) From the steady decay of radioactive atoms in the rock.
B) From heat left over from the planet's birth.
Both A and B
What causes auroras?
Particles from the Sun colliding with and exciting atoms in our upper atmosphere.
What causes the greenhouse effect ?
Water vapor and carbon dioxide absorb infrared radiation from the ground and reradiate the heat toward the surface.
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