Mr. Bizzarro EARTH SCIENCE

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Mr. Bizzarro EARTH SCIENCE
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Unit 1
Introduction to Astronomy
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Early Astronomy
? Astronomy is the science that studies the
universe. It includes the observation and
interpretation of celestial objects.
? A celestial object is an object in the sky that
is not associated with the Earths atmosphere.
? Examples stars, moons, planets, and comets.
? Not Celestial Objects rainbows, clouds, and
birds.
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Earth on a turtles back
Flat Earth
The Greek Titan Atlas
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Evidence of Ancient Astronomy
Stonehenge
The Great Pyramids
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A Geocentric Universe
? Geocentric Model
In the ancient Greeks geocentric model, the
Earth was the center of the universe. The moon,
sun, and the known planets Mercury, Venus, Mars,
and Jupiter orbited the Earth.
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Geocentric Model
Star Sphere
Sun
Earth
Venus
Planet Epicycles
Moon
Mercury
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Apparent Motion
Apparent motion of the Moon and Stars
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Apparent Motion
? Apparent motion of celestial objects
All celestial objects seem to rise in the
east, move across the sky, and set in the west.
All celestial objects seem to move across the
sky at 15o per hour.
Why?
The Earth is actually rotating from west to
east at a rate of 15o per hour.
15o per hour X 24 hours 360o per day.
Thats one full rotation.
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Problems with the Geocentric Model
? Problem with the Geocentric Model
Certain stars were changing position in
reference to the other stars in the sky
They called these stars planetes for the Greek
word that meant wanderer.
Retrograde Motion of Mars
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Copernicus
? Nicolaus Copernicus
Copernicus concluded that Earth is a planet.
He proposed a model of the solar system with the
sun at the center.
Heliocentric Model model of the solar system
with the sun in the middle.
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Heliocentric Model
Star Sphere
Sun
Earth
Venus
Mercury
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Galileo Galilei
? Galileo Galilei
Galileos most important contributions were
his descriptions of the behavior of moving
objects.
He developed his own telescope and made
important discoveries
1. Four satellites, or moons, orbit Jupiter.
2. Planets are circular disks, not just points of
light.
3. Venus has phases just like the moon.
4. The moons surface is not smooth.
5. The sun has sunspots, or dark regions.
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Earths Motions
? The two main motions of Earth are rotation and
revolution.
Rotation the spinning of the Earth on its
axis
The Earth is tilted at 23 ½ degrees.
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Tilted Axis
In fact all planets have a tilted axis
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Evidence of Rotation
1) Foucault Pendulum
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Foucault Pendulum
Foucault Pendulum in 1851, French scientist
Jean Foucault built a pendulum that proved to the
world that the Earth rotated
Jean Foucault
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Newton's 1st Law an object in motion will stay
in motion in the same direction until a force
acts upon it.
Foucault Pendulum Animation School of Physics
Foucault Pendulum About Foucault Pendulums
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Evidence of Rotation
2) Coriolis Effect
Coriolis Effect objects get deflected from s
straight line path due to the rotation of the
Earth. Examples Planes, Wind and Ocean Currents
Objects in the Northern Hemisphere are
deflected to the right.
Objects in the Southern Hemisphere are
deflected to the left.
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Notice the wind of the hurricane is
being deflected to the left. What hemisphere
must in be occurring in?
Coriolis Effect on Planes Coriolis Effect
Interactive Game Coriolis Effect on Wind
Coriolis Effect Video
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Coriolis Effect on Ocean Currents
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Rate of Rotation
The Earth makes one complete turn (360o) every
24 hours.
That means that the Earth rotates at 15o per
hour. 360o / 24 hours 15o/hour
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Effects of Rotation
1) Day and Night only half of the Earth can
face the sun at one time.
What would happen if the Earth didnt
rotate?
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Effects of Rotation
2) Time Zones because the Earth is rotating
different parts of the world are experiencing
different times of day.

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World Time Zones
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Effects of Rotation
3) Apparent Motion of Celestial Objects
because the Earth rotates, all celestial objects
seem to move across the sky at 15o per hour.
Example Sunrise and Sunset
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Effects of Rotation
4) Star Trails time exposure taken with a
camera
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Polaris
Polaris a star located almost directly
over the North Pole
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Location of Polaris
Polaris is in the handle of the little dipper
and found using the pointer stars of the big
dipper
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The Big dipper is a circumpolar constellation,
which means its a group of stars that appear to
circle around Polaris.
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Polaris and Latitude
The angle of Polaris from an observers
location will determine their latitude on Earth
Albany New York is at about 43o latitude
so Polaris will always appear to be at 43o angle
when we see it.
Flash Animation of the angle of Polaris
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Earths Motions
? The two main motions of Earth are rotation and
revolution.
Revolution the traveling (orbiting) of the
Earth around the sun.
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How and Why does the Earth Revolve?
Gravity the force of attraction between two
objects. The amount of Gravity depends on two
things 1) The mass of the objects 2) The
distance between the objects
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Evidence of Revolution
Star Parallax
We see different stars throughout the year.
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Rate of Revolution
The Earth makes one complete revolution (trip
around the sun) every 365 ¼ days. Also known
as 1 year.
Revolution Animation
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Shape of the Earths Orbit
? The shape of the Earths orbit is elliptical or
an ellipse.
An ellipse is an oval-shaped path.
Notice the sun is not in the middle of the
ellipse.
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Perihelion and Aphelion
Revolution
Perihelion is the time in January when Earth
is closest to the sun.
Aphelion is the time in July when Earth is
farthest from the sun.
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Effects of Revolution
because the Earth is tilted and revolves
around the sun, we have different seasons.
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The equator splits the northern and southern
hemisphere and is 0o latitude.
The Tropic of Cancer is 23.5o north latitude.
The Tropic of Capricorn is 23.5o south
latitude.
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Dates of the Seasons
Seasons in the Northern Hemisphere
Date First day of which season? Name of the day Where are the direct rays of the sun?
March 20st - 22nd Spring Vernal Equinox Equator 0o
June 21st - 22nd Summer Summer Solstice Tropic of Cancer 23.5oN
September 22nd 23rd Autumn Autumnal Equinox Equator 0o
December 21st - 22nd Winter Winter Solstice Tropic of Capricorn 23.5oS
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All about the seasons animation
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Equinoxes
Equinoxes because the Suns direct rays are
on the equator, everywhere on the Earth has 12
hours of day and 12 hours of night.
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Solstices
Solstices summer solstice is the longest
amount of daylight we get all year (15 hours)
while winter solstice is the shortest (9 hours)
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Revolution and Earths Speed
Because Earths orbit is an ellipse the Earth
changes its speed.
When it is closer to the Sun it moves faster
to escape the suns gravity.
When it is further from the Sun it can move
slower.
Recall Gravitational force decreases with
distance.
Animation of Orbital Velocity
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Revolution and Earths Speed
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Gravitys Influence on Orbits
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Other Planets and Revolution
The further the planet from the sun, the
longer its period of revolution will be.
Cool visualization with Haleys Comet
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Eccentricity of Ellipses
?Eccentricity
Eccentricity is how circular an ellipse is.
The Eccentricity of a perfect circle is zero.
Eccentricity 0
The Eccentricity of a straight line is one.
Eccentricity 1
All Ellipses must have an Eccentricity between
0 and 1.
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Ellipse-O-Tron 2000
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Parts of an Ellipse
Major Axis
Every ellipse has two foci (plural of focus),
which are equal distance from the center and rest
on the major axis
The major axis is a line that runs through the
widest part of the ellipse.
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Calculating Eccentricity
The formula for eccentricity of an ellipse can
be found in the ESRTs. Eccentricity
distance between foci / length of major axis
10cm
16cm
Eccentricity 10cm / 16cm Eccentricity .625
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When determining the eccentricity of a planets
orbit, you always use the Sun as one foci.
The other foci is an imaginary point that is
equal distance from the center of the ellipse
Change the Ellipse
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Drawing an Ellipse
You can draw an ellipse. All you need is a
pencil, two tacks, and some string. You will be
doing this on an upcoming lab.
You also can find the eccentricity of all of
the planets orbits in your ESRT. Click Here
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Online Quizzes
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