Transcript TEKS Presentation Earth and Space Systems

STAAR:
Earth and Space Systems
Middle School Science
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Changes in the Earth over time
Weathering- the process of rocks being broken
down into smaller pieces.
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Two types of Weathering
Mechanical
Rocks break into
smaller pieces by
physical means –
Water, ice, wind,
gravity, organisms
& changing
temperatures
Chemical
Rocks break into
smaller pieces by
chemical reactions –
Air, water, acid &
salts react with
minerals in rocks to
form new
substances
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Erosion
Destructive


The movement of
particles from one
location to another is
erosion
Weathered particles of
rock are transported by
gravity, living organisms,
water, glaciers & wind.
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Deposition

Constructive
The settling (depositing) of eroded
particles as sediments wherever they
are transported by wind or water.
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Rock Cycle
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Plate Tectonics
Plate tectonics explains the movement of large
sections of Earth’s crust called tectonic plates. The
force behind tectonic plate movement is thought to be
currents of magma flowing in Earth’s mantle.
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Plate boundaries
Tectonic plates slowly collide against one another
along plate boundaries. Sections of the plates
may break off and be pushed down, up, or to the
side. Mountain ranges, ocean trenches,
earthquakes & volcanic activity are all common
along plate boundaries.
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Pacific Plate
is the largest
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All the land that
drains into a
specific body
of water.
Groundwater
and surface
water both
contribute to
the water in a
watershed.
Surface water
becomes
groundwater
by soaking
into the sand
and soil or by
traveling
through cracks
in rock.
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Two important ways that oceans affect climate on land
1. Land heats up faster than water because land has a lower specific
heat than water does. This causes the air over land to heat faster
than the air over water. The warm air rises, starting a convection
current that pulls air toward land from the ocean. This keeps air
over the land from getting too hot and brings moist ocean air
inland.
2. Warm air holds more water vapor than cold air does. When warm,
moist air is cooled, clouds form and can produce precipitation.
This warm air can be cooled by rising into the colder upper
atmosphere, by moving over cold ocean or lakes, or by mixing
with colder air. (Ex. Front boundary- the edge where cool, dry air
meets warm, moist air. Often causes stormy weather)
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Nitrogen
Cycle
Nitrogen
changes back &
forth from
nitrogen gas to
the nitrogen
compounds used
by plants &
animals.
Nitrogen is passed from plants to other organisms through food
webs in the ecosystem. Once plants & animals use the nitrogen it
returns to the atmosphere as a gas, completing the cycle.
Some fertilizers contain nitrogen compounds because plants need
nitrogen to grow. Though there is plenty of nitrogen gas in the
atmosphere, plants can’t use this form. In nature nitrogen can be
changed from a gas to a form that plants can use by lightning or by
soil bacteria and fungi in a process called nitrogen fixation.
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Problems if too much Nitrogen in
environment
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Carbon Cycle
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Effects of carbon on environment
One of the biggest ways
humans affect the carbon
cycle is by burning fossil
fuels.
Burning fossil fuels
transforms carbon into
carbon dioxide.
Higher levels of carbon dioxide cause the
atmosphere to hold more heat energy. This may
be the cause of warmer temperatures measured
in recent years on Earth. (Called “The
Greenhouse Effect”)
This could affect the climate in many places.
The kinds of plants and animals in these
climates may change if the warming continues.
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Without the carbon and nitrogen cycles, there
would be no life on earth!
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Catastrophic events affect the earth
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Ways humans affect the earth
Two common
forms of
pollution:
1. Gases released
into the
atmosphere
2. Chemicals that
are carried by
water into a
watershed
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Humans can cause extinctions
Human can change:
•The quality of the air, water & soil we use
•Ecosystems by removing plants & animals & by
introducing new species, such as invasive plants &
pets
•Invasive species don’t naturally live in the
ecosystem where they are introduced.
•Invasive species compete with/or drive out native
species (species that live naturally in an
ecosystem)
FIRE ANTS- invasive species- accidentally introduced to North
America from South America. They have few predators in NA &
aggressively attack & kill many kinds of native plants & animals.
They have upset the balance of ecosystems in many southern
states.
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Renewable
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Non renewable
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Inexhaustible
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Eclipses
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Solar eclipse
When the moon is aligned so that its shadow falls on
Earth’s surface, the sun’s light is blocked from reaching
part of the Earth. Called solar eclipse because it’s the sun
that is being blocked from our view.
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Lunar Eclipse
A lunar eclipse occurs when Earth blocks sunlight from
reaching the moon. This puts the moon in Earth’s shadow.
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4 main Phases of the Moon
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Moon phase diagram
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Moon’s Revolution & Rotation
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Have you ever noticed that
the sun travels lower across
the sky in winter than in
summer? This is because
Earth is tilted on its axis at a
23.5o angle.
Seasons
During winter
part of Earth
tilts away
from the sun.
This causes
the sun’s
rays to strike
that part of
Earth at a
lower angle
than in the
summer.
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Seasons-
Remember it’s the
TILT of the
Earth that causes the seasons
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Winter Solsticeshortest day of the
year
Days are shorter & nights are
longer during winter. This
occurs in December in the
Northern Hemisphere & in
June in the Southern
Hemisphere.
Each hemisphere receives
less sunlight & therefore less
heat energy during the
winter. This is why
temperatures are colder
during winter.
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Summer
Solsticelongest day of the
year
This occurs in June in the
Northern Hemisphere and in
December in the Southern
Hemisphere.
Earth’s revolution around the
sun causes part of the Earth to
tilt toward the sun at different
times of the year. This causes
that part of the Earth to
receive more sunlight at a
more direct angle. This is why
days are longer and nights are
shorter.
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Equinox- means
“Equal Night”
Equinox
Daytime lasts
exactly as long as
nighttime on the
first day of
autumn – the
Autumnal Equinox
(about September
21) and the first
day of spring the Vernal Equinox
(about March 21).
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8 Planets
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The Sun & Gravity
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The Sun is a Star
Our sun is a medium-size
yellow star.
In the sun, hydrogen
undergoes nuclear fusion, a
process that releases vast
amounts of energy. During
fusion hydrogen atoms join to
form helium atoms.
Hydrogen fusion
is the source of
light, heat, and
other radiation
from the sun.
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Comets
Comets are made of various solids (like dirt &
dust) and ice crystals. When their orbits take
them close to the sun, dust and ice heat up to
produce a “tail” behind the comet. Larger
comets may even become visible without the
aid of a telescope.
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Asteroids
Asteroids are rocky and usually
follow regular orbits around the
sun.
Asteroid belt- the area between
Mars and Jupiter that contains
many asteroids orbiting the
sun.
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Nebulae
Nebulae are huge clouds
of dust and gas. Some
scientists think that our
solar system was formed
from nebula.
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Galaxies are
groups of
millions or
billions of stars.
The galaxy we
live in is the
Milky Way galaxy
and has over 100
billion stars. It
would take
100,000 light
years to travel
across it!
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300,000,000
meters per second
is the same as
300,000
kilometers per
second.
That’s the
Speed of
Light!
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Closest star to Earth
(besides the Sun)
Proxima Centauri is the nearest star to our
Solar System.
Traveling at the speed of light, it would take about
4 years & 3 months to reach it from Earth. (That
makes it about 280,000 times farther away from
Earth than our sun!)
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H-R Diagram
In the Hertzsprung-Russell diagram each star is
represented by a dot. Stars are plotted by their luminosity
(brightness) and surface temperature.
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