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The Solar System consists of:• Sun• objects that move around it

•Planets•their moons•Asteroids (small rocky bodies)

Our Sun is a star at the center of our solar system.

Every object in the system follows their own independent path, or ORBIT around the Sun. GREAT VIDEO: Explore the Solar System! Next

SOLAR SYSTEM

Click here for definition

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The Moon• Some planets have more than one moon• Some planets have none

A moon is a satellite• A body that orbits a larger body• Artificial satellites also circle earth

The moon takes approx. 29 ½ days to circle earth• Roughly 1 month

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Our Sun

•Our sun is small compared to some other stars•100 times the diameter of our planet•93 million miles from earth

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to understand why:•tropics are warm •arctic regions are cold •day is warmer than night

Geographers study Earth’s

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rotation, revolution& the tilt of its axis

ROTATION

• One complete spin of Earth on its axis is called rotation. • Each rotation takes 24 hours, or one day.• Earth turns on its axis, (but to us it appears that the Sun is moving)

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The Earth’s rotation is slowing down very slightly over time…

…about one second every 10 years.

FACT

REVOLUTION

• One complete orbit around the sun. • It takes the Earth one year, or one revolution, to orbit the Sun• More precisely, it takes 365 ¼ days

LEAP YEAR•Every fourth year becomes leap year•An extra day- February 29th – is added•Allows for this fraction of a day•Keeps the calendar accurate

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How fast is the earth revolving around the sun?

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QUESTION…

ANSWER…The Earth

• revolves around the Sun at a speed of about 18.5 miles/sec

AXISAn imaginary line that runs from the North Pole through Earth’s

center to the South Pole.

• Earth’s axis is tilted, or slanted, at an angle of 23.5˚ • Because of Earth’s tilt, as Earth revolves around the Sun…

• the angle at which the Sun’s rays strike the planet is constantly changing

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How fast is the earth spinning around its axis?

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QUESTION…

ANSWER…

• At the equator, the Earth's surface moves 40,000 kilometers in 24 hrs

• A speed of about 1040 miles/hr

• toward either pole, this speed decreases to almost zero

(since the circumference of the spinning circle at the extreme latitudes approaches zero)

Day

It takes the Earth 23.93 hours to rotate around its axis once

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Year It takes the Earth 365.26 days to orbit the Sun once.

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SummaryEarth spins on its axis: an invisible line through the center of the Earth.

North Pole: The northernmost point of this axis

South Pole: The southernmost point of this axis

Equator: invisible line that encircles the widest point of the Earth

The Equator is the same distance away from each pole at every point along it.

TROPICS

Areas in the low latitudes near the equatorSun’s rays are nearly vertical throughout the year.

POLAR REGIONS:

Areas near the North and South Poles The Sun’s rays are always at a low angle. Result; Poles are generally the coldest places on earth(click below for “illustrated” definitions)

The Arctic Circle: Circles the North PoleAntarctic Circle: Circles the South Pole

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SEASONS

A year is divided into periods of time called seasons:Each season is known for certain type of weather based on…

•temperature•amount of precipitation

Seasons Change as Earth orbits the SunThe amount of solar energy received , changes

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Solstices: • The 2 days when the Sun’s vertical rays are

farthest from the equator

Solstices occur twice a year: • June 21 • December 21

June 21st December 21st

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The Earth orbits, on average, 93 million miles from the Sun.

NORTHERN HEMISPHERESummer solstice

• the Sun's rays strike Earth directly at the Tropic of Cancer • June 21st• longest day of the year • beginning of summer

Winter solstice• shortest day of the year• December 21st, • North Pole is pointed away from the Sun• the Sun’s rays strike Earth directly at the Tropic of Capricorn

SOUTHERN HEMISPHERE

• the seasons are reversed • winter solstice is June 21• summer solstice is December 21

MIDDLE LATITUDE REGIONSlie between:

• the Tropic of Cancer & the Arctic Circle• the tropic of Capricorn & the Antarctic Circle. Next

CLICK for “illustrated”

definitions

CLICK for “illustrated” definitions

SOLSTICES AND THE SUN...

From mid-Autumn into mid-Winter, the South pole is tilted toward the sun;

• this is when the Northern hemisphere experiences shorter hours of daylight.

• The South pole now experiences the 24-hour daylight, right around the time of the Winter solstice. Next

SOLSTICES AND THE SUN...From mid-Spring through mid-Summer, the North pole is tilted toward the sun;

• this is when the Northern hemisphere experiences longer hours of daylight.

• The North Pole has several days of total sunlight right around the solstice Next

Earth's axis tilt & equatorial plane compared with its plane of orbit

NextCLICK HERE for an Excellent Video on Equinoxes and Solstices etc.

The two days of the year when the Sun’s rays strike the equator directly.

Equinoxesdefinition

NORTHERN HEMISPHERESpring Equinox

• the Sun's rays strike Earth directly • Every place on earth has 12 hrs of day & 12 hrs of night• Mark the beginning of spring• “Vernal equinox”• March 21st

Fall Equinox• the Sun's rays strike Earth directly• Every place on earth has 12 hrs of day & 12 hrs of night• Mark the beginning of fall• “Autumnal Equinox”• September 22nd

SOUTHERN HEMISPHERE • the seasons are reversed • Spring equinox is September 22nd • Fall equinox is March 21st Next

The Earth SystemThe interactions of forces and materials on the planet.Contains four parts;

•Atmosphere: Layer of gases- the air- that surrounds earth•Lithosphere•Hydrosphere•Biosphere

Gases include;•Nitrogen•Oxygen•Carbon dioxide

The atmosphere also contains:OZONE: A form of oxygen in the atmosphere that helps

protect Earth from harmful solar radiation.

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Summary Here you see the Earth rotating on its axis, and also revolving around the sun.

The solstices & equinoxes will briefly flash on the screen for each time of year

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“Solstice and Equinox”

Click here for a GREAT interactive

Earth spins around its axis as it orbits the Sun.

Our entire Solar System slowly orbits around the Milky Way Galaxy.

The Milky Way Galaxy belongs to the Local Group of galaxies, where it is also moving. Click here for an interactive activity on SeasonsClick here for an excellent video on Seasons

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Websites to visit:

SOLAR SYSTEMdefinition

The Sun and the objects that move about it, including planets, moons, and asteroids.

http://janus.astro.umd.edu/javadir/orbits/ssv.htmlhttp://janus.astro.umd.edu/javadir/orbits/ssv.html

June 21st

BackSummer Solstice

December 21st

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Solstice The days when the Sun’s vertical rays are farthest from the equator

Winter Solstice

Tropic of Cancer

line of latitude 23.5. north of the equator

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Tropic of Capricorn

line of latitude 23.5. south of the

equator

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ARCTIC CIRCLE

line of latitude 66.5˚ north of the equator

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ANTARCTIC CIRCLE

line of latitude 66.5˚ south of the equator

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Middle Latitudes

TROPIC OF CAPRICORN

TROPIC OF CANCER

ARCTIC CIRCLE

ANTARCTIC CIRCLE

TROPIC OF CANCER

ANIMATION

ROTATION

Nexthttp://janus.astro.umd.edu/javadir/orbits/ssv.html

Aurora over Edmonton, Alberta