Glossary of Astronomy Chapter 5

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What are some of the major differences between the moon and earth?
Moon has no atmosphere, hydrosphere, or magnetosphere.

Moon is smaller

Moon has a LARGER Crust

Earth has a liquid outer core

Moon has a rocky inner core (?)

Moon has alot more craters.

Earth has water and sustains life.
The moon is actually very similar to what planet?
What causes the tides?
The moon's gravitational pull on earth creates two bulges on Earth- one that is closest and one that is furthest from the moon.
Why does it make sense that the moon's gravitational effects creates TWO bulges?
because we have 1 tide change (2 tides- low and high) in every 24 hours.
What are the long-term effects of the moon's gravitation causing tides? There are 2
1.) Earth's rotation has slowed. This as a result of friction between the oceans and earth. (.002 sec/century)

2.) increasing the size of the moon's orbit (2 inches/year further from Earth)
What is unique about the moon's rotation around the Earth?
It is tidally locked.
What does it mean for the moon to be tidally locked with the Earth?
The moon's rotation is the same as its orbit. Thus, we always see one side of the moon ("Dark side of the moon")
Is there actually a side of the moon that is always dark?
No. There is just a side we never see.
What are the largest chemical componenets in Earth's atmosphere?
-Carbon dioxide
What are the purposes of the atmosphere?
protects us from UV and falling objects

regulates and stabalizes temperatures.
What layer of the atmosphere does convection (Weather) occur?
What is convection?
The idea that hot air rises and cold air sinks. This creates surface winds and most types of weather.
What is the Greenhouse Effect?
Infared radiation from the sun that is not reflected by clouds heats the earth. But then becomes complexed in CO2 and water vapor further heating the earth. Before, the IR radiation would be reflected back toward the Sun.
Why is the Greenhouse effect actually a good thing?
It keeps the earth warm enough to sustain water which in return sustains life.
Why does earth have an atmosphere while the moon does not?
Because Earth is so much more massive it has a higher gravitational pull on its atmosphere. Earth is said to have a higher escape speed. Molecules would need to be traveling faster than they can to escape earth's gravitational force.

Recall the moon is less massive and has 1/6th the gravity.
So we know why we can attract our atmosphere, how come it doesnt come down on earth?
Because of Convection. The heated earth mantains its atmosphere off from the surface but surrounding earth.
How do we know what is at the center of Earth if we cannot drill that far?
Seismic activity by earthquakes are monitored and we utilize the concept that waves travel through different materials at different speeds to determine what the center of earth is made up of.
The earth is divided into three geologic sections what are they?
Crust mantle and core
The crust is about how deep?
15 km (thicker on continental crusts.
How thick is the mantle? What percentage of the Earth's volume is found in the mantle?
3000 Km ; 80%
How thick is the core?
3500 km
what elements make up the inner core?
Iron and nickel. most internal core is hottest and densest.
What three processes led to the solidification of Earth?
Crust formation
What is accretion and when did it occur?
(4.6 Billion years ago) Earth was bombarded with interplanetary debris which made it VERY HOT.
What is differentiation?
The denser material that had fallen on earth sunk directly to the core. differentiation occured by density.
what is crust formation?
The process of the earth's crust hardening when the earth finally began cooling.
Where is there earthquake activities today?
At plate tectonic boundaries.
what causes these earthquakes?

Warmer mantle moves up spreading the sea floor causing drifting continents and mid ocean ridges.
The moon is much more cratered than earth. Why is that? (3 reasons)
No shifting of plate tectonics to level the surface.

No rain or water

lack of atmosphere
Lunar surfaces have two main features. What are they?
Maria and highlands
How do we age the craters on the moon?
By adjacent highland and maria regions.
What happened about 3.9 billion years ago that slowed the amount of craters bombarding the solar system?
the accretion process ended.
Magnetic field lines travel from ________ to ______.

Are magnetic poles at the geographic poles?
North to south

No, they are close but 11 (?)degrees off.
What effect does the sun have on Earth's magnetic field?
Solar wind distorts the Earth's magnetic field.
What is the Aurora Borealis?
The lights that can be seen in the sky at the North Pole.
What causes the Aurora Borealis?
Charged particles that have escaped Earth's magnetic fields and collide with the Earth's atmosphere.
What causes Earth's magnetic field?
The rotation of the planet coupled with the electrically conducting effect of liquid metal at the core.
Wnat is the internal electric conducting process that produces the Earth's magnetic field called?
The Dynamo effect.
What are the two FALSE theories of how the moon was formed?
1.) The moon is a sister planet of Earth (Not possible, moon is too different in composition).

2.) Moon was formed elsewhere and captured. (Not possible the mantle of Earth and the moon are too similar)
What then is the leading theory of the formation of the moon.
After the earth had differentiated (little metal at the core) a Mars sized body hit Earth and later the pieces formed the moon.

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