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8th Grade Final Study Guide
Astronomy:
1. Define revolution and give an example.
1 complete trip around another object. Ex. The Earth revolves around the sun in about 365 days. The
moon revolves around the Earth in about 29 days.
2. Define rotation and give an example.
1 complete spin on an axis. Ex. The Earth takes about 24 hours to complete one rotation.
3. What two factors affect the gravitational pull between objects?
Mass and distance
4. Draw the positions of the sun, Earth, and moon.
5. Which planet takes the shortest amount of time to revolve around the sun? Which takes the
longest?
Shortest: Mercury – closest to the sun
Longest: Neptune – farthest from the sun
6. Draw the moon phases and label.
7. Describe the path of the sun in each of the four seasons.
Summer – high in sky, longer path, longer
daylight
Spring & Fall – medium height, equal day
and night
Winter – low in sky, shorter path, shorter
daylight
8. How long is Earth’s rotation? How long is Earth’s revolution around the Sun?
Earth’s rotation = about 24 hours
Earth’s revolution = about 365 days.
9. If you increase the gravitational force of the Sun on Earth, what would happen to Earth? Why?
The Earth would move closer to the sun, and eventually will crash into the sun.
10. What two factors keep a planet in its orbit?
Gravity and inertia
11. Explain what happens in a lunar eclipse with a picture. What moon phase is needed? When
(time) does it occur?
The Earth is between the sun and the
moon. The Earth blocks the sunlight,
so it casts a shadow on the moon.
Full moon needed.
Occurs at night.
12. Explain what happens in a solar eclipse with a picture. What moon phase is needed? When
(time) does it occur?
The moon is between the sun and the
Earth. The moon blocks the sunlight
from reaching part of the Earth, so it
casts a shadow on a small area of the
Earth.
New moon needed.
Occurs during the day.
13. What causes Earth’s seasons? Explain.
The tilt of the Earth as it revolves around the sun. Different parts of the Earth get more direct sunlight than
others.
14. What is New Jersey’s longest day of the year? What is it called?
June 21st, Summer Solstice
15. What is New Jersey’s shortest day of the year? What is it called?
December 21st, Winter Solstice
16. If the Northern Hemisphere is experiencing summer, what is the Southern Hemisphere
experiencing? Why?
The Southern Hemisphere will experience winter because it is tilted away from the sun, while the
Northern Hemisphere is tilted towards the sun.
17. What shape does everything orbit in?
In an ellipse
18. If gravity disappeared within our solar system, what would happen? Explain.
Everything would move away from each other. Gravity holds everything in place.
Plate Tectonics and Rocks/Soil:
18. Draw a convergent boundary. What is occurring in your picture?
Plates move towards each other.
If 2 continental plates- forms mountains
If 2 oceanic plates – forms island arcs
If 1 continental and 1 oceanic – forms volcanoes
19. Draw a divergent boundary. What is occurring in your picture?
Plates move away from each other.
If 2 continental plates- forms rift valley
If 2 oceanic plates – forms ridges
20. Draw a transform boundary. What is occurring in your picture?
Plates slide past each other.
Causes earthquakes.
21. At which type of boundary do most earthquakes occur? Why?
Transform boundaries because built-up tension is released when the plates rub against each other.
22. What is a subduction zone? Explain.
When a continental and ocean plate collide, the most dense plate will sink under the less dense plate.
23. Before the continents split, what was the name of the giant continent? What evidence do we
have for the continents drifting apart?
Pangaea was the giant landmass, made of all the continents put together.
Evidence:
Matching mountains on different continents
Matching plant and animal fossils on different continents
Glacier marks in Africa and Australia
Continents seem to fit like a puzzle
24. What causes the Pacific Ring of Fire? What happens here to create most of the volcanoes and
earthquakes on Earth? Explain.
Subduction Zones along the Pacific Ocean where continental plates are colliding with oceanic plates and
one of the plates subducts under the other.
25. What is convection? How does it explain plate tectonic movement? Where does it occur?
Convection – circulation of heat. There are convection currents in the magma in the mantle. The plates
(lithosphere) float on the asthenosphere (mantle) because the magma is circulating.
26. What is sedimentary rock? How is it usually formed? What does it usually contain?
Rocks that are made from other rocks that have been weathered and eroded, and then compacted and
cemented together. They contain small rocks, pebbles, shells and fossils.
27. What is igneous rock? Where does it most likely come from?
Rocks that are made from cooled magma or lava.
28. What is metamorphic rock? How is it formed?
Rocks that are made when other rocks undergo extreme heat and pressure underground and chemically
combine.
29. Which type of rock is most common on Earth’s surfaces? Why?
Sedimentary rock, because the process of forming them all occurs on the Earth’s surface.
30. Explain sea floor spreading. How does it occur?
Seafloor spreading occurs at a divergent boundary when 2 oceanic plates move away from each other
and magma rises from the asthenosphere to form a ridge.
31. During Earth’s history there has been multiple mass extinctions. Give at least 2 examples of
what caused the extinctions.
Climate change – warming up or cooling down
Asteroid impacts from space
Atmospheric changes – rise and falls of CO2
Sea level changes
Weathering and Erosion:
32. Define weathering. Define erosion.
Weathering – the breaking down of rock by wind, water, and heat.
Erosion – the transporting (moving) of rock by wind, water, or ice.
33. What is chemical weathering? Give 2 examples.
When materials are broken down through chemical processes and form a new product. Example: rust
forming on a nail. Statues dissolving with acid rain. The oxidation of the Statue of Liberty.
34. What is mechanical weathering? Give 2 examples.
When the physical characteristics of materials are broken down, but are not changed into new products.
A rock breaking because of heat. A tree root cracking the sidewalk. Pot holes in the road created by ice.
35. What would cause a mountain to decrease in size over millions of years? Explain.
Weathering and erosion of the mountain by wind, water, or ice. The rocks of the mountain will break
down over time and be carried away.
36. What causes the formation of beaches? Explain!
The constant hitting of the waves against the rocks break them down until they are tiny particles of
sand.
37. What do scientists use to date rock layers? Explain.
Scientists use index fossils which are only found in specific rock layers.
38. Use the picture below to answer the questions:
A. List the rock layers in order from youngest to oldest.
A, B, H, C, E, F, D, G
B. What happens to layer A over time?
It’s been weathered and eroded.
C. What was the last event to occur in the picture?
The fault that crosses along all of the layers.
Atmosphere & Weather
1. Draw and label a picture of the Water Cycle. Explain how water moves through the Water
Cycle.
Evaporation - Liquid water gains energy
from the sun (heats up) and turns into water
vapor (gas), going up into the atmosphere.
Condensation - Warm air rises and loses
energy (cools down. Water vapor forms
liquid water droplets that create clouds.
Precipitation – When warm air loses
energy (is cooled), water droplets can no
longer hold in clouds and will fall as rain
(above 32oF), sleet, snow (below 32oF), or
hail.
Run-off - When extra water from storms,
melted snow, or other water sources flow on
the lands surface back into a body of water.
2. Why is the grass wet in the morning? Explain what is causing this to occur.
Because the air temperature drops below the dew point temperature, so the water vapor (gas) in the air
condensed on the grass as liquid water droplets.
3. Explain what type of front is occurring. What type of weather would occur? How would the
temperature change?
A warm front (warm air) is pushing out a
cold front (cold air). This will cause the
temperature in that area to increase.
4. Explain what type of front is occurring. What type of weather would occur? How would the
temperature change?
A cold front (cold air) is pushing up a warm
front (warm air). This will cause the
temperature in that area to decrease after a
thunderstorm occurs.
5. What is a barometer? How is it used to help meteorologists predict weather?
A barometer is a tool used by meteorologist to measure changes in air pressure. High air pressure means
sunny weather. Low air pressure means stormy weather.
6. What is humidity? What factors can affect the amount of humidity in the air?
Humidity is the measure of water vapor in the air. Location, season, and time of day can affect the amount
of humidity in the air.
7. List the 3 types of heat transfer below.
A. Radiation – heat transfers through heat waves (without touching). Example: the sun’s rays
warming the Earth or giving your skin sunburn.
B. Convection – heat transfer through circulation of a fluid. Warm materials rise, cold materials
sink. Example: Heat rising in your house, cold air from the AC sinking. Boiling water circulating in
a pot.
C. Conduction – heat transfer through touch. Example: a cold spoon getting hot in a bowl of soup.
Burning your feet while walking on hot sand at the beach.
8. What created the gases in the early atmosphere? How was the early atmosphere different from
today’s atmosphere?
Gases released from volcanic eruptions created the early atmosphere. The early atmosphere was
poisonous.
9. Draw a cold front. What kind of air does it
bring?
Cold air pushes away warm air.
10. Draw a warm front. What kind of
air does it bring?
Warm air pushes away cold air.
11. Use the weather map below to answer the questions.
Tennessee
A. Why is there so much rain over the Central U.S.? (Explain both symbols)
There are many low-pressure systems along a stationary front. Low-pressure systems bring rain, and
because the front is stationary, the air is not moving, causing extended periods of rain.
B. Explain what kind of weather is occurring in Tennessee? Why?
Sunny weather because there is high pressure in that area.
12. Name the 5 layers of the atmosphere in order from closest to Earth’s surface to furthest. Give
one or two examples of what happens in each layer. How does the density of air change as you
move up through the layers?
Exosphere – where Earth’s atmosphere meets
space. LEAST DENSE LAYER
Thermosphere – where space shuttles orbit;
Layer with auroras.
Mesosphere – coldest layer; meteors burn out
here.
Stratosphere – airplanes fly here; ozone layer
here
Troposphere – weather occurs here; where we
live. MOST DENSE LAYER