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Astronomy
DO NOW/Warm-Up
Answer Question:
What do YOU know about the Universe?
Discovery Education : A View of the Universe
•
Write Questions in Do Now Section of Binder Follow along by answering the
questions as you watch the video
• Title: Discovery Education : A View of the Universe
– What is another name we can use to call the universe?
– What can each point of light in the universe become?
– What is the yellow star in the spiral galaxy orbited (circled) by eight planets
called?
– About how old is the universe?
(http://player.discoveryeducation.com/views/hhView.cfm?guidAssetId=fafa34ff-5c7c-44f5-9422e989f1967d1c&play=true&preview=true&skin=&small=true)
Day 1 Lesson Objective
Today you will be able to:
1. Explain the origin of the Earth’s motion based on the origin
of the galaxy and its solar system.
2. Recall Earth’s role in the hierarchy of organization within the
universe and in the developmental continuum. (Universe is
made of galaxies which are made of many stars. Some stars
have planetary systems similar to our solar system. Earth is a
satellite planet of one particular star.)
How our Universe Formed
•Theory of how the universe formed called the
Big Bang Theory
•Big Bang Theory – the universe formed from a
massive expansion approximately 14 bya
The Universe is
expanding and the
visible edge is about
13.7 billion light
years away
The universe began billions of
years ago as a tiny dot that
exploded into today’s huge system
of stars and planets.
Support for the Big bang Theory
• Red shifts
• Cosmic background radiation
–Radio signals coming from every
direction in space.
–Believed to be created by the big
bang explosion.
The Expanding Universe
• 1929 – Edwin Hubble found that
the universe is expanding
– Estimated distances, relative brightness,
Doppler red shifts
Dimmer galaxies had greater red
shifts  farthest from Earth
https://www.youtube.com/watch?v=y5
tKC3nEx2I
Milky Way
Galaxy…spiral
shaped!
Hubble’s Law: the more distant the
galaxies have greater red shifts,
therefore they are moving away at
faster speeds.
Hubble Law Lab
Hubble’s Law : the more distant galaxies have
greater red shifts, therefore they are moving away
at faster speeds.
Hubble’s Law
Transitioning to Objective # 2
• Recall Earth’s role in the hierarchy of
organization within the universe and in the
developmental continuum. (Universe is made of
galaxies which are made of many stars. Some
stars have planetary systems similar to our solar
system. Earth is a satellite planet of one
particular star.)
Note: Our solar system is part of a bigger
system called a galaxy. Our galaxy (Milky Way)
is part of a bigger system called the universe
Milky Way
Galaxy…spiral
shaped!
Galaxies and Stars
Galaxies – billions of star groups
more than 100 billion galaxies, each containing
billions of stars
Milky Way
Galaxy…spiral
shaped!
So, how did our Solar System form?
•The Nebular Theory – explains that solar
system was formed from a rotating disk of
dust and gas
•Formed ~4.6 bya
1.Solar System began as a giant
ball of dust and gases (after the
Big Bang)
2.Cloud flattened as it spun
around, forming an accretion disk.
►Sun formed in the middle from all
the heat in the middle of the disk
3.Cooling of the disk caused small
shapes to form
4. These cool forms combined to
make the 4 SOLID inner planets
5.The lighter material combined
farther away, forming the 4
GASEOUS outer planets
Do Now
1. What is the big bang theory?
2. What is some evidence to support the big
bang theory?
3. What is a red shift and what does that tell us
about distance of objects in space?
4. Explain in your own words what Hubble’s
Law states. Hint: think about your lab from
last class
Day # 2 Objective 3 &4
Today you will be able to:
• Explain planetary orbits especially that of the Earth, using
Kepler’s laws.
• Explain relative motion of the Earth in the solar system, the
solar system in the galaxy, and the galaxy in the universe—
including the expanding nature of the universe; Orbital motion
(Earth around the Sun- once/year, seasons depend upon an
approximate 23.5 degree tilt); Rotation around our axis
(day/night,)
Earth’s Role in the Solar System
• The universe is made of galaxies which are
made of many stars. Some stars have
planetary systems similar to our solar system.
Earth is a satellite planet of one particular
star (our sun).
Three Ways in Which the Earth
Moves
The Earth:
1.Rotates (Rotation)
2.Orbits
3.Revolves (Revolution)
Ways the Earth Moves
• Rotates = spins.
• The earth makes 1 full rotation every 24
hours.
• The axis of the Earth is tilted at an angle of
23.5 degrees.
• The axis always points towards the
North Star
Ways the Earth Moves
• We have day and night because of the Earth’s
rotation.
• Draw the picture below in your notes
Ways the Earth Moves
• The Earth also revolves around the sun in
an elliptical orbit.
• The earth makes one full revolution around
the sun every 365.25 days.
365 days = 1 year
Kepler’s Laws
• Provide Definition of Kepler’s
Laws, Precession, Nutation and
Barycenter.
• Draw a picture illustration
• Explain how you would act it
out
How Earth’s Formation Affected Earth
•Earth orbits the Sun following Kepler’s 3
laws of planetary motion
1. The path of each planet around the
Sun is an ellipse
2. Equal areas are covered in equal time
3. The length of time it takes a planet to
orbit the Sun is proportional to its
distance from the Sun
Kepler (15711630) came up
with these
scientific laws
and they are
still used in
Astronomy
today!
http://www.youtube.c
om/watch?v=pJlTuv
Hg6wY&feature=fvsr
st
1 Law: Law of Ellipses
The path of the
planets around
the sun are
elliptical in
shape with the
center of the sun
being located at
one focus
The shape of
the ellipse is
determined by
the location of
the two focus
points!
nd
2 Law: Law of Equal Areas
This law states that an imaginary line
from the sun to a planet sweeps out
equal areas in equal time intervals
nd
Kepler’s 2 Law of Planetary Motion
Are they the SAME?
• The short wide glass is holding the SAME amount of
water as the tall skinny glass!
Planet moves FASTER in orbit when
CLOSE to the SUN, and SLOWER in orbit
when FAR FROM the SUN
GRAVITATIONAL PULL
WHY?
Keppler’s 3rd Law
Kepler’s Three Laws of Planetary
Motion (A Summary)
1.
Each planet takes an elliptical path around the sun
2.
Planets travel faster when they are close to the sun and slower
when they are farther away from the sun
3.
The amount of time needed for a planet to revolve around the
sun is proportional to the the planet’s distance from the sun
A
B
C
Precession
 The direction this axis of a planet is pointing in
will change, but the tilt will not change.
 This will change the stars near the pole but will
not change the seasons (as long as the angle
of the tilt, 23.5 in the case of Earth, stays the
same)
Precession Animation
• http://www.youtube.com/watch?v=CUZOXcz
MfMo
Nutation
 Nutation happens when the axis of a planet
starts to wobble (do the wobble!)
 The angle of the axis will change during nutation
½ degree one direction or the other
 Nutation happens over the course of 18 years
 Nutation is a direct result of the moon (or
moons) of a planet
Barycenter
 A barycenter is the point between
two objects where they balance
each other (For example, the
middle balancing point on a scale).
Barycenter Example
 For example, the moon does not orbit the
exact center of the Earth, but a point on a line
between the Earth and the Moon
approximately 1,710 km below the surface of
the Earth, where their respective masses
balance.
 This is the point at which the Earth and Moon
orbit as they travel around the Sun
Do Now
1. Draw a picture of the Earth on it’s axis.
At what degree is it tilted?
2. Describe Kepler’s first law.
3. What does the law of equal areas state?
4. Draw a picture depicting his 1st and 2nd
law.
5. Describe Kepler’s third law.
Application and Critical Thinking Questions
1. In degrees, what is the tilt of the Earth?
2. Summarize and explain all 3 of Kepler’s laws of
planetary motion into one or two sentences.
3. How does precession affect the Earth’s rotation and
revolution?
4. Explain in your own words what nutation is .
5. Based on the concept pf barycenter, explain the
evolutional relationship between the sun and the
earth.
Exploring Orbits: Eccentricity Lab
• Goal: To draw variously-sized elliptical orbits
by changing the locations of the two foci
points and then using that information to
analyze the orbits of our solar system’s
planets.
• Video
Demonstration:https://www.youtube.com/wa
tch?v=P-Gq75hQdfw
Demo/Group Work Activity
1. What does eccentricity measure?
2. Ms. Sterling observed the orbital path of
Mars. From the data she collected, she found
the focal point length to be 10 light years and
the major axis length to be 22.5 light years.
Find Mars’ eccentricity based on her
observations.
3. Planet X has an eccentricity of 0.0803 and
Plant Y has an eccentricity of 0.8030. Using
these measurements explain the paths of
these planets around the sun.