TAKS objective 5Earth and Space Systems

Middle School ScienceScience TAKS Need to Know

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Changes in the Earth Over Time

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Weathering- the process of rocks being broken down into smaller pieces.

Two Types of Weathering

MechanicalRocks 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

• 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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Destructive

Deposition• The settling (depositing) of eroded

particles as sediments wherever they are transported by wind or water.

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Constructive

Rock Cycle

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Plate Tectonics

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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.

Plate BoundariesTectonic 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.

TAKS Need to Know 9Pacific Plate Pacific Plate is the largest 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

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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)

Nitrogen Cycle

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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.

Problems with too much Nitrogen in the Environment

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Carbon Cycle

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Effects of Carbon on Environment

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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!

Catastrophic Events Affect the Earth

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Ways Humans Affect the Earth

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Two common forms of pollution:

1. Gases released into the atmosphere

2. Chemicals that are carried by water into a watershed

Humans Can Cause Extinctions

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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.

Renewable

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Non renewable

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Inexhaustible

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Eclipses

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Solar eclipse

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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.

Lunar Eclipse

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A lunar eclipse occurs when Earth blocks sunlight from reaching the moon. This puts the moon in Earth’s shadow.

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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Seasons

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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.

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.

Seasons- Remember it’s the TILT of the Earth that causes the seasons

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Winter Solstice- shortest day of the

year

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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.

Summer Solstice-

longest day of the year

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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.

Equinox

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Equinox- means “Equal Night”

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).

8 Planets

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The Sun & Gravity

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The Sun is a Star

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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.

Comets

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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.

Asteroids

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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.

Nebulae

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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)

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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!)

H-R Diagram

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In the Hertzsprung-Russell diagram each star is represented by a dot. Stars are plotted by their luminosity (brightness) and surface temperature.