Download Unit 8: The Earth is Space

Unit 10: The Earth in Space
I The Apparent Motions of Celestial
Objects.
 The stars, sun, moon, and planets
appear to move through the sky.
 Much of this motion is really caused by
the Earth moving through space.
A. Vocabulary
1. Celestial Sphere: the dome of the sky
overhead
2. Zenith: highest point on the celestial
sphere, directly overhead.
3. Horizon: the rim of the celestial sphere,
where the sky meets the ground.
4. Azimuth: the angular distance around
the horizon.
North=0° East=90° South=180° West=270°
5. Altitude: the angular distance above the
horizon.
[Diagram]
B. Apparent Motion of the Stars
1. The stars appear to move through the
sky at 15°/hour. (text p.701)
[Why?]
 In the northern sky Polaris remains
motionless
 Other stars appear to rotate around
Polaris counterclockwise.
[Diagram: star trails, northern sky]
star trails - Google Image Search
http://www.astronomy.ohio-state.edu/~pogge/Ast161/Movies/circumpolar.mov
YouTube - APOD 2009 April 13 Star Trails over the Canada France Hawaii Telescope
YouTube - Star Trails around Polaris
YouTube - Star Trail Time Lapse
 In other parts of the sky, stars rise in the
Eastern horizon and set in the Western
horizon.
[Diagrams: star trails, East, South, West]
YouTube - Time-Lapse of Startrails over The Dish Radio Telescope Parkes, Australia
2. Constellations: are patterns of stars
forming imaginary pictures in the sky.
(text p.700)
The constellations that can be seen at night
change from season to season.
This is because of the Earths revolution
around the sun. (text p.748-749)
Different Constellations at Different Times of the Year
[diagram]
C. Apparent Motion of the Sun
1. Daily Motion
 The sun traces an arc through the sky at
15°/hour. [Why?]
 The sun rises in an Easterly direction
and sets in a westerly direction.
 The sun reaches its highest point around
12:00 Noon.
2. The higher the sun in the sky the shorter
shadows appear.
[diagram]
 Shadows point the opposite direction
from the position of the sun.
 Shadows are longest at sunrise and
sunset.
 Shadows are shortest around 12:00 noon.
3. The path of the sun in NY changes with
the seasons.
Earth Science Students - CLICK HERE!!! - Animations and Visual Learning
Aids
Date
Name
Sun Length
Rises of Path
June 21st Summer NE Longest
Solstice
September Autumn Due Medium
21st
Equinox East
December Winter SE Shortest
21st
Solstice
March
Spring Due Medium
21st
or
East
Vernal
Equinox
Noon
Position
Highest
(72°)
Medium
( )
Lowest
(23°)
Medium
()
4. In New York State…
 The noon time sun is always in the
southern sky. (shadows point north)
 The noontime sun is never directly
overhead.
 The suns apparent diameter changes by
season.
Sun
Sets
NW
Due
West
SW
Due
West
[Diagram]
This occurs because the Earth is closer to
the sun in Winter and further away in
summer.
YouTube - Sun's Path-Hommocks Earth Science Department
C. Apparent Motions of the Planets
1. From Earth, 5 planets are visible with
the unaided eye:
Mercury, Venus, Mars, Jupiter, and Saturn
2. When tracked over many months,
planets wander or “zig-zag” relative to the
background stars.
“Planethos (Greek) – the wanderers”
[Diagram]
The backward motion of planets, relative to
stars, is called Retrograde Motion.
http://www.astronomy.ohio-state.edu/~pogge/Ast161/Movies/marsretro95.mov
3.Apparent brightness and size of planets
change in a cyclic pattern.
[Diagram]
see text p.619 fig. 7
II Models of Celestial Motion
A. Geocentric Model: the Earth is the
center of the universe. The stars, sun, moon,
and planets all orbit the Earth.
Geo = Earth
centric = centered
1. Developed by Ptolemy of Egypt
(200 AD)
Read text p.615-616
[diagram]
2. Features:
 Earth is stationary (unmoving) at the
center.
 Explains motion of sun, moon, and stars
well.
 Becomes too complicated when
explaining retrograde motion of planets.
(Epicycles)
http://www.astronomy.ohio-state.edu/~pogge/Ast161/Movies/ptolcoper.mov
Ptolemys Model of Motion of a Planet
B. Heliocentric Model:
Helios = Sun
centric = centered
1. Developed by Copernicus (Polish
Catholic Priest) around 1543 AD.
(Read text p.617)
2. Further developed by Galileo (Italian
Scientist) around 1630 AD using data from
newly invented telescope.
(Read Text p.619)
YouTube - Galileo's Battle for the Heavens 1
YouTube - "Galileo" Indigo Girls
3. Features:
 The sun is the center of the solar system.
 Stars are unmoving and a great distance
away.
 The moon orbits the Earth.
 Earth and other planets orbit the sun.
 Earth rotates on its axis.
 Explains motion of celestial objects
better than the geocentric model.
C. Real Motions of the Earth in Space
1. The Earth Rotates on its axis.
 The axis of rotation is tilted 23.5°
relative to its orbit around the sun.
[Diagram]
 Earth rotates at 15° /hour.
 Earth takes 23 hours 56 min. to complete
one rotation.
 Earths rotation causes night and day.
2. Proof that the Earth rotates:
 Coriolis Effect makes winds and ocean
currents curve.
[diagram]
Observe an animation of the Coriolis effect over Earth's surface.
 Foucault’s Pendulum changes its
direction of swing. (see text p.635)
[diagram]
Examine evidence of Earth turning about an axis
YouTube - foucalt pendulum
3. The Earth Revolves around the sun.
 It takes 365.25 days to complete one
revolution.
 This motion and the tilt of the axis
produce seasons on Earth.
YouTube - Earth Rotation-Hommocks Earth Science Department
D. Earth Motions and the Seasons
[diagram: earths orbit]
Explore a model of Earth's yearly revolution around the sun.
1. The Summer Solstice- around June 21st.
[diagram]
 Sun has its longest path. longest hours of
daylight (15.5 hours), and highest noon
time position in NY.
 First day of summer in Northern Hem.
 North pole tilted 23.5 towards the suns
rays.
 Suns vertical ray strikes 23.5 N. Lat., the
Tropic of Cancer.
2. Autumn Equinox- around September
21st.
[Diagram]
 12 hrs.daylight / 12 hrs. dark everywhere
on Earth.
Equinox = “equal day/night”
 First day of Autumn in the northern
hemisphere.
 Suns vertical rays strike lat. 0°, the
equator.
3. Winter Solstice- Around December
21st.
 Sun has shortest path, least hours of
daylight, and lowest noon time position in
NY.
 First day of Winter in the northern hem.
 North pole tilted 23.5° away from sun.
 Suns vertical ray strikes lat. 23.5° S., the
Tropic of Capricorn.
4.Spring or Vernal Equinox- around
March 21st.
 First day of Spring in the northern hem.
 All other features same as Autumn
equinox.
YouTube - Seasons-Hommocks Earth Science Department
E. Laws of Planetary Motion developed by
Tycho Brahe (1546-1601) and
Johannes Kepler (1571-1630).
YouTube - Carl Sagan on Tycho Brahe, Johannes Kepler, and ellipses
1. Keplers 1st Law: Earth and other
planets move in Elliptical Orbits around the
sun.
[diagram]
vidclip: elliptical orbits
 Ellipse has two Foci. The sun is located
at one focus of the ellipse.
 Perihelion: Planet closest to sun.
Aphelion: Planet furthest from sun.
 Eccentricity is a measure of how
elliptical a planets orbit is.
 The more elliptical the orbit, the greater
the eccentricity.
[Diagram]
 Eccentricity = Distance between foci /
Length of major axis
e=d/L
See ESRT p.1
Example: [diagram]
 If e = 0, orbit is perfectly circular.
 If e = 1 orbit is a straight line.
 Orbital eccentricities of all planets lie
between 0 and 1.
(see ESRT p.15)
 Planet with most eccentric orbit:
__________
 Planet with least eccentric, most circular,
orbit:
__________
YouTube - Ellipses-Hommocks Earth Science Department
2. Keplers 2nd Law: Planets move faster in
their orbit when closer to the sun and slower
when they are further away.
The Force of Gravity is stronger between the
planet and a star when they are closer
together.
[diagram]
3. Keplers 3rd Law: The greater a planets
average distance from a star, the greater its
Period of Revolution.
(See ESRT p.15)
[diagram]
[lab: Elliptical Orbits]
III Earths Moon
moon - Google Image Search
(Origin- p.633)
A. Features:
 About ¼ the size of Earth
 Gravity about 1/6 that of Earth.
 No Atmosphere. Sky always appears
black and stars shine all day.
 No liquid water, no life.
 Surface composed of light colored
lunar highlands and darker, flat, maria.
 Many Impact Craters formed from
colliding Meteorites.
B. The moon revolves in an elliptical orbit
around the Earth as the Earth revolves
around sun.
[demo]
 Period of Revolution = about 27.3 days.
 Period of Rotation = Period of Rev.,
therefore same side always faces Earth.
 Apparent diameter varies in a cyclic
pattern. [Why?]
[Diagram]
C. The Phases of the Moon are caused by
the relative positions of the Sun, Moon, and
Earth.
About 29.5 days to complete a cycle of
phases. (text p.626)
1 “moonth” became 1 month.
[set up diagram]
1. New Moon: invisible, none of lit side
can be seen from Earth.
[add to diagram]
2. Waxing Crescent: a thin ‘sliver’ of lit
side can be seen.
[add to diagram]
3. First Quarter: ½ of lit ½ can be seen.
[add to diagram]
4. Waxing Gibbous: almost all of lit side
can be seen.
[add to diagram]
5. Full Moon: Entire lit side of moon can
be seen.
[add to diagram]
6. Waning Gibbous
7. Third Quarter
8. Waning Crescent
[add to diagram]
diagram-moons phases
YouTube - moon phases
YouTube - Phases of the Moon 3D animation
D. Eclipses occur when the Sun, Moon,
and Earth are in a straight line.
1. Solar Eclipses occur when the moon
passes directly between the Earth and
Sun. (text p.628)
Only occurs during New Moon phase.
(Why not every New Moon?)
[diagram]
YouTube - The Solar Eclipse In Varanasi - Wonders of the Solar System - Series 1 Episode 1 Preview - BBC Two
NASA Eclipse Web Site
2. Lunar Eclipses occur when the Earth
passes between the sun and moon.
Only occurs during the Full Moon Phase.
(text p.628)
[diagram]
YouTube - Lunar Eclipse - August 28, 2007 Hawaii
E. The gravitational pull of the Moon and
Sun causes the level of the Ocean to rise
and fall.
These are called Tides. (text p.458)
1. The moon has a greater affect on tides
than the sun because it is closer to the Earth.
2. High Tides occur on side of Earth
facing the moon and opposite side.
3. Low Tides occur in places midway
between high tides.
[diagram]
4. Higher high tides and lower low tides
occur when sun and moon combine
their pull of gravity (text p.459)
 This occurs during New and Full Moon.
 Tides then have the greatest Tidal
Range.
 This called a Spring Tide.
5. Lower high tides and higher low tides
occur when sun and moon’s gravitational
pull oppose each other.
 This occurs during the 1st and 3rd quarter
phases.
 Smallest tidal range.
 This called a Neap Tide.
YouTube - Ocean Tides at the Bay of Fundy (Britannica.com)
YouTube - Ocean Odyssey - Tides & Waves
YouTube - Hopewell Rocks, New Brunswick, Canada
YouTube - The Moon-Hommocks Earth Science Department
IV The Solar System is composed of all
objects in orbit around our sun.
(text p.644-664)
Origin- p.647 read
YouTube - Birth of the Solar System
A. The Sun: Earths Star - Features:
Avg. of 93 million miles away or 8.3
light minutes.
[Fastest jets would take about 10 years to
reach the sun]
Volume of sun could hold 1 million Earths!
Surface temp. about 6,000 C.
Core temp. at least 15 million C.!
(Sun layers- text p.685)
1. The sun, and all stars, are powered by
Nuclear Fusion. (see text p.689)
[Diagram]
2. Sun is the source of energy for almost
all life, weather, ocean currents and waves.
3. Cooler, darker areas of Sun’s surface
called Sunspots (see text p.687).
 Number of sunspots vary in a cyclic
pattern. (see text p.691)
 Sunspots may influence climate patterns
on Earth.
4. Solar Prominences and Solar Flares
occur on the surface of the sun.
(see text p.688)
 Can effect long distance radio
communication.
 Causes Aurora’s (northern and
southern lights).
B. The Inner or Terrestrial (Earth-like)
Planets: are all relatively small and rocky.
They are Mercury, Venus, Earth, and Mars.
(see ESRT p.15)
1. Mercury see p.650
 Surface covered with impact craters.
 Extreme temp. range between night and
day.
2. Venus- p.650
 Very thick atmosphere composed mainly
of CO2
 “Runaway greenhouse effect”.
 Average temp. 900 F.!
3. Earth:
 Unique among planets in the solar
system.
 Only place known to contain life.
4. Mars: Text p.652
 Thin atmosphere; mainly CO2
 Polar Ice Caps, extinct volcanoes
 Deep Canyons and Dry River Beds
carved by flowing liquid water.
mars rovers photographs - Google Search
C. The Outer or Jovian (Jupiter like)
Planets are all relatively large and mainly
composed of gas.
They are: Jupiter, Saturn, Uranus, and
Neptune.
1. Jupiter: text p.654
 Largest of all the planets; perhaps a
“failed star”.
 Mainly composed of Hydrogen and
Helium gas.
 Four largest moons: Io, Europa,
Callisto, and Ganymede. (p.655)
2. Saturn: Text p.656-657
 Composed mainly of Hydrogen and
Helium
 Known for beautiful rings composed of
orbiting ice and rock.
 Largest moon, Titan, has thick
atmosphere of Methane gas.
3. Uranus:
(Text p.658)
 Discovered in 1781
 Composed mainly of Hydrogen and
helium
 Axis of rotation tilted 90°
 Largest moons are Oberon, Umbriel,
Ariel, and Miranda
4. Neptune:
(p.658)
 Discovered 1846
 Largest moons are Triton and Nereid
YouTube - The Real Perspective on the Solar System - With Music
YouTube - Our Solar System - Size Of Planets and Stars to Scale
D. Other members of our Solar System
1. Asteroids are large rocky objects that
range in size from pebbles to about 600
miles in diameter. (Text p.661)
 Mostly located in the Asteroid Belt
between Mars and Jupiter.
 Some asteroids have struck the Earth in
the past leading to catastrophic effects
on life.
(Mesozoic/Cenozoic Boundary and
extinction of dinosaurs)
2. Comets are icy objects with highly
elliptical orbits
[diagram]
When comets near the sun, heating causes a
tail.
Ex. Halley’s Comet appears about every 75
years.
[Kuiper Belt, Oort Cloud- text p.662]
3. Minor Planets include Pluto and many
other icy objects located at the fringe of the
solar system.
YouTube - The Solar System - Space School
YouTube - Reference Table Page 15-Solar System Data Chart-Hommocks
Earth Science Department
V Earth in the Universe
A. The Life Cycle of a Star depends on its
mass.
(see text p.709-710)
YouTube - A Star's Life Cycle
YouTube - The Life Cycle Of A Star
(Black Holes- text p.714)
YouTube - Black Hole Montage - NASA Galaxy Big Bang - PHJ
B. The Hertzsprung-Russell (H-R)
Diagram is used to classify stars based on
temperature and brightness.
(see ESRT 15, text p.704)
Practice:
Star
Temp. K. Color
Luminosity
(Brightness)
4,000
25,000
300
50,000
Sun
Rigel
Polaris
Alpha
Centauri
C. Distances to the Stars
1. A Light Year is the distance light
travels in one year, moving at 186,000
miles/sec.
(1 LY = about 6 trillion miles)
2. When viewing stars you look back in
time!
Ex. Proxima Centauri- 4.3 LY away
Polaris- 300 LY away
Betelguese- 490 LY away
How we know the distances to stars: text
p.699, 702
D. Stars are clustered into groups called
Galaxies which come in different shapes and
sizes. (see text p.717)
“Islands of stars in the Ocean of Space…”
1. Our sun is located in a spiral arm of the
Milky Way galaxy. (see text p.715-716)
[Diagram]
YouTube - Milky Way in 3D
2. Galaxies are grouped into Galactic
Clusters. (Text p.718)
Milky Way and 17 other galaxies form the
Local Group.
YouTube - Stars-Hommocks Earth Science Department
YouTube - Solar System-Hommocks Earth Science Department
YouTube - Galaxies-Hommocks Earth Science Department
5.The Universe is everything that is…
The universe contains billions of galaxies;
as far as our instruments can see (current
limit about 15 billion LY!)
YouTube - Hubble Deep Field: The Most Imp. Image Ever Taken (Redux)
Is there life elsewhere in the universe?
Is there intelligent life elsewhere?
IV How did the Universe begin?
How will it end?
A. The Big Bang Theory: the entire
universe began with a giant explosion of
matter and energy.
1. Explosion occurred about 14 Billion
years ago.
The Universe has been expanding ever
Since (text p.719-720)
B. Supporting Evidence (text p.718-720)
1. Light from distant galaxies is stretched
out.
 It is “redder” than it should be.
 This means galaxies are moving
away from each other.
 The further a galaxy from us, the
greater the red shift.
This called Hubbles Law.
[Diagram]
YouTube - What Is a Redshift?
YouTube - Hubble's Expanding Universe Red Shifts The Big Bang
2. Background Radiation is found equally
in all directions in space. This is the
“hum” or “echo” of the Big Bang.
YouTube - The Universe-Hommocks Earth Science Department