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Chap 1 Earth Moon & Sun
Key Concepts and Key Terms
41
Science
8th Grade
09/23/2011

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Term
Astronomy
Definition

The study of the moon, stars, and other objects in space.

 

Term
Axis
Definition
imaginary line that passes through Earth's center and the North and South poles.
Term
Rotation
Definition
The spinning of Earth on its axis.
Term
Revolution
Definition
The movements of one object around another.
Term

Revolution vs Rotation

Seasons

Definition

Earth Rotates on Axis causing Day/Night

 

Earth Revolves around Sun causing Years

 

Earth has Seasons because its axis is tilted as is revolves around the Sun

Term
Solstice
Definition

Each of two days when the Sun is FARTHEST NORTH or FARTHEST SOUTH of the equator.

 

Term
Summer Solstice
Definition

Farthest North = Northern Hemesphere

Longest day = June 21

Summer there

Term
Winter Solstice
Definition

Farthest South of Equater

Northern Hemisphere = shortest day

Deceber 21

Winter in Northern Hemisphere

 

Term
Equinox
Definition
  • Half way between solstices, neither hemisphere is tilted toward or away from the sun.
  • Day and night are equal about 12 hours long
  • Sept 22= Autumnal 
  • March 21 = Vernal
Term
Force
Definition
a push or pull
Term
Gravity
Definition
attracts all objects toward each other
Term
Newton's law of universal gravitation
Definition
every object in the universe attracts every other object
Term
force of gravity-2 factors
Definition

mass of the objects

distance between objects

Term
mass
Definition
amount of matter in an object
Term
weight
Definition

the force of gravity on an object

can change with location

you way 1/6 your weight on the moon

Term
distance
Definition

gravity decreases when distance increases

distance doubles the gravity goes to one forth

Term
inertia
Definition
tendency of an object to resist a change in motion
Term
Newton's first law of motion
Definition
object at rest will stay at rest and an object in motion will stay in motion unless acted on by an outside force
Term
inertia and gravity
Definition
the 2 factors that together keep earth in orbit around the sun and the moon in orbit around earth
Term
phases
Definition
  • the different shapes of the moon you see from Earth
  • the changing relative positions of the moon, Earth and sun case them
  • What you see depends on how much of the sunlit side of the moon faces Earth
Term
eclipse
Definition

When the moon's shadow hits Earth or the Earth's shadow hits the moon

 

 

Term
Two types of Eclipses:  Lunar and Solar
Definition

Solar= Sun > Moon > Earth

Moon passes directly in between Earthand sun, blocking sunlight from Earth

 

Lunar= Sun > Earth > Moon

Earth blocks sunlight from reaching the moon

Term
umbra
Definition
  • the darkest part of the moons shadow that is cone shaped in a Total Solar Eclipse where the light of the sun is completely blocked out
  • the darkest part of the earth's shadow on the moon is a Total Lunar Eclipse only on Full Moons where the moon is total blocked out...it has a red tint from the Earth's atmosphere
Term
penumbra
Definition

the larger part of the shadow wher part of the sun is visible during a Solar Eclipse and part of the moon is visible during a Lunar Eclipse

 

this is where you see a Partial Solar or Partial Lunar Eclipses

Term
tides
Definition
caused mainly by differences in how much the moon's gravity pulls on different parts of the Earth
Term
spring tide
Definition
when the sun moon and earth line up ( doesn't matter the order so it could be full moon or new moon) the sun also pulls on the Earth's waters and you have:  THE GREATEST DIFFERENCE between low and high tides
Term
neap tide
Definition

during the 1st and 3rd quarter of the phases of the moon, the line between the Earth and the sun and the moon is at right angle

sun > earth

   ^

      moon

 

The LEAST DIFFERENCE between high and low tides

Term
High and Low Tides
Definition

Closest to Moon and Farthest from Moon = high

between the two high tides = low

see diagram on page 26 fig 16

Term
Tilts of the Earth Summary
Definition

Summer Solstice: June 21 North end of Earth to Sun

Autumnal Equinox: Sept. 22 no end of Earth to Sun

Winter Solstice:  December 21: South end of Earth to Sun

Vernal Equinox: March 21: no end of Earth to Sun

Term
telescope
Definition
a device built to observe distant objects by making them appear closer
Term
Features on the moon's surface
Definition

maria

craters

highlands

Term
maria
Definition

the hardened rock formed from huge lava flows that occurred 3-4 billion yrs ago

 

appear as dark flat areas using telescope

Term
craters
Definition

large round pits made from the impact of meteoroids hitting the moon

Term
meteoroids
Definition
chunks of rock and dust from space
Term
highlands
Definition

mountains on the moon's surface that are light-colored features

 

cast dark shadows on the rims of the craters

Term
Characteristics of the Moon
Definition
  • dry
  • airless
  • compared to Earth, it is small
  • has large variations in its surface temperature
Term
Size and Density of the Moon
Definition
  • 3.4 thousand Kilometers in diameter=little less than distance across US
  • 1/4 Earth's diameter
  • 1/80 the mass of the Earth
  • Moon's density = density of Earth's outer layers
Term
Temperature and Atmosphere
Definition

Direct Sunlight = 130*C

Night = -180*C

Without an atmosphere the temperature vary so much

With little gravity the gases escape into space so there is no air

Term
Water
Definition

The moon has no liquid water

 

Evidence of ice near Moon's poles that is covered from sunlight by crater walls and tem is so low - that would be where a colony would be built if anywhere on Moon

Term
the origin of the Moon = The Collision-Ring Theory
Definition
the moon formed early in Earth's history when a planet-sized object struck Earth.  The resulting debris formed a ring and the gravity caused the material to combine together to form the moon.
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