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29 Cards in this Set
- Front
- Back
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How Many planets are there? |
Eight excluding Pluto |
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the earth is believed to have foamed by |
1. acceleration of dust and particles 2. differation into layers |
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Nebula |
a huge clouds of gas and space dust |
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Nebular hypothesis |
all bodies in the solar system formed from an enormous cloud composed mostly of hydrogen and helium with only a small percentage of heavier elements |
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the differentiated earth |
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where did the water come from? |
1. Out gassing of volcanoes 2. External Source "comets" and meteorites |
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how old is the earh? |
around 4.6 Billion years old |
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what makes scientist think the earth is 4.6 billion years old |
rocks |
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what can scientist find that's dated between 3 and 2 billion years old? |
the oldest prokaryotes |
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between 2 billion and 1 billion years ago the earth lacked |
o2 but had a increase in co2 not the earth has more o2 than co2 this is also called the oxygen crisis |
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why do we think the earth differentiate into layers 4.6 billion years ago. |
the age composition and position of layers based on -the study of gravity - seismic studies |
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how do we know about the structure of the earth |
Gravity |
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what does gravity studies include |
-earth orbiting satellites -gravity surveys on land |
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The earth orbiting satellites tell us two thing |
-Earths shape in an oblate spheroid -The average density (mass/volume) of the earth |
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Positive anomaly= |
gravity reading is higher than average |
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Negative Anomaly = |
gravity reading is lower than average |
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what causes a gravity anomaly and how do you figure it out |
First, figure out expected differences and make corrections Next, compare corrected values to look for differences (anomalies) |
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Why are Gravity anomalies useful |
because it is the difference between the observed acceleration of free fall, or gravity, on a planet's surface, and the corresponding value predicted from a model of the planet's gravity field. |
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What is seismic studies |
using seismic waves |
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what is seismic waves |
vibrations that are transferred through the solid earth |
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what is p waves |
primary waves affects solid and liquid |
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what is s waves |
secondary waves affecting only solids |
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vibration parallel = |
primary waves |
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vibration perpendicular = |
secondary waves |
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what is shear |
is a force acting tangentially over the surface of a body. |
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shear is in what wave |
secondary |
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compression is in what waves |
primary |
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what is compression |
is a force acting axially on the body. |
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what is a seismometer |
equipped for measuring the direction, intensity, and duration of earthquakes by measuring the actual movement of the ground. |
