2011 Pearson Education, Inc. Units of Chapter 2 2.1 Ancient Astronomy 2.2 The Geocentric Universe 2.3 The Heliocentric Model of the Solar System The

© 2011 Pearson Education, Inc.

Units of Chapter 2

2.1 Ancient Astronomy

2.2 The Geocentric Universe

2.3 The Heliocentric Model of the Solar SystemThe Foundations of the Copernican Revolution

2.4 The Birth of Modern Astronomy


Units of Chapter 2, continued

2.5 The Laws of Planetary MotionSome Properties of Planetary Orbits

2.6 The Dimensions of the Solar System

2.7 Newton’s Laws

2.8 Newtonian MechanicsWeighing the Sun


White Board Question• What are some ancient structures that people used

the sun and stars to help keep track of time and seasons?



• Ancient civilizations observed the skies

• Many built structures to mark astronomical events

Summer solstice sunrise at _____________:


2.1 Ancient AstronomySpokes of the _________________________in Wyoming are aligned with the rising and setting of the Sun and other stars



This temple at _______________, in Mexico, has many windows that are aligned with astronomical events


2.2 The Geocentric Universe

Earth based

Ancient astronomers observed:

Five planets:


2.2 The Geocentric UniverseSun, Moon, and stars all have simple movements in the sky

Planets:• Move with respect to fixed stars

• Change in brightness

• Change speed

• Undergo retrograde motion


Golden Age600 BC-AD 150Aristotle

• _______ philosopher (384-322 BC)

• Earth is _____________• Casts a curved shadow when

passes between _________ and ______

His belief was abandoned during the Middle Ages


_________________276-194 BC

• First successful attempt to figure out the size of the earth

____________________2nd Century BC

• Divided stars into six groups according to brightness

• Method for predicting lunar eclipses


________centric model• _______________________

orbit the earth• _________________(stars)

orbits the earth• Incorrect


2.2 The Geocentric UniverseEarliest models had ____________________ at center of solar system

Needed lots of complications to accurately track planetary motions


Carl Sagan on epicycles

http://www.dailymotion.com/video/xerwsh_carl-sagan-videos-epicycles-of-ptol_tech

Take notes:


_____________centric Model

• First heliocentric astronomer--Aristarchus (Greek 312-230 BC)

• Earth and other planets orbit the sun


Heliocentric vs. Geocentric Model

Model Location of Earth

Location of Sun

Who supports

__________Center of the universe Orbits

_______

Heliocentric _________ ________ of the universe


White board question• On your white board make a Venn Diagram

comparing Heliocentric and Geocentric views of the universe.

Ptolemaic System

• Claudius ______________ wrote a 13 volume work on Greek astronomy

• ___________centric, used ___________ to explain the varying brightness of planets and planet retrograde motions

• Used mathematical terms to explain the heavenly bodies


2.3 The _____________________ Model of the Solar System

This figure shows retrograde motion of Mars.

_______________ is at center of solar system. Only Moon orbits around Earth; planets orbit around Sun.


Understanding retrograde motion

• http://astro.unl.edu/classaction/animations/renaissance/retrograde.html

• Interactive– http://highered.mcgraw-hill.com/olcweb/cgi/

pluginpop.cgi?it=swf::800::600::/sites/dl/free/0072482621/78780/Retro_Nav.swf::Retrograde%20Motion


White board• Explain retrograde motion to your

neighbor, see if you can write it out


Discovery 2-1: The Foundations of the Copernican Revolution

1. ____________ is not at the center of everything.

2. Center of Earth is the center of _________ orbit.

3. All _________________revolve around the Sun.

4. The ________________ are very much farther away than the Sun.

5. The apparent movement of the stars around the Earth is due to the Earth’s __________________.

6. The apparent movement of the Sun around the Earth is due to the Earth’s __________________.

7. ______________________motion of planets is due to Earth’s motion around the Sun.



_________________________ invented around 1600

___________________ built his own, made observations:

• Moon has mountains and valleys

• Sun has ___________, and rotates

• ______________has moons Venus has ________________

Galileo and Venus

• How did Venus retrograde motion definitely prove that the sun is at the center of the solar system?

• Turn to your table group and see if you can figure it out



_______________cannot be explained by geocentric model

_______________1546-1601Denmark

• Developed instruments to measure the locations of heavenly bodies

• Collected a vast amount of data that Keplar was able to use to build his laws of planetary motion


2.5 The Laws of Planetary Motion

___________________were derived using observations made by Tycho Brahe

Johannes Kepler1571-1630

• Three laws of planetary motion–Kepler observed:

• Mars orbit was elliptical• As Mars approaches the sun it speeds up and slows down as it goes away from the sun

Three laws of planetary motion1. The path of each planet around the sun is an ellipse

with the sun at one focus.

2. Each planet revolves around the sun so that it sweeps over equal areas in equal amounts of time causing it to travel more rapidly in areas closer to the sun.

3. The square of the orbital period is proportional to the cube of its distance from the sun.



Law 1. Planetary orbits are ________________, Sun at on a


Time to try it on your own

• An ellipse can be drawn with the aid of a string, a pencil, and two thumbtacks. The wider the separation of the foci, the more elongated, or eccentric, is the ellipse. In the special case where the two foci are at the same place, the curve drawn is a circle.



Law 2. Imaginary line connecting Sun and planet sweeps out _________________________

Keplar’s 2nd law

http://www.youtube.com/watch?v=5a2mcE-tzKE


2.5 The Laws of Planetary MotionLaw 3. Square of ____________ of planet’s orbital motion is proportional to cube of _______________________________________


More Precisely 2-1: Some Properties of Planetary Orbits

____________________: closest approach to Sun

__________________: farthestdistance from Sun

Another way to say them• The path of the planets about the sun is elliptical in shape,

with the center of the sun being located at one focus. (The Law of _________________________)

• An imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time. (The Law of ___________________) http://www.physicsclassroom.com/mmedia/circmot/ksl.cfm

• The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun. (The Law of ________________________)

Easy math

If planet A is 4 units from the sun then what is its orbital period. (a3 = p 2)

Keplar’s laws

http://www.youtube.com/watch?v=5a2mcE-tzKE

http://www.youtube.com/watch?v=GcKiG-CuvtA

Let’s watch different planets in action

• http://astro.unl.edu/classaction/animations/renaissance/kepler.html

__________________

• Mathematician• Invented calculus to solve the gravity


2.7 Newton’s Laws

____________________

____________________

____________________explain how objects interact with the world and with each other.

Newton: Three laws of motionLaw 1:

An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. This law is often called “________________________".

http://teachertech.rice.edu/Participants/louviere/Newton/law1.html

White board question

• If everything in an airplane is traveling at the same speed when do you feel the motion?

Law 2

• Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).

• http://teachertech.rice.edu/Participants/louviere/Newton/law2.html

• Force=____________________________• Forceg=mass x gravitational acceleration

Definitions

• ___________________ is an intrinsic property of an object and remains the same independent of where it is in the universe

• _________________is the downward force experienced by an object as a result of gravitational interaction

A little math

• If Marvin the Martian is 100 lbs on Earth how much would he weigh on the moon if the surface gravity is 17% of that on Earth?

Weight=mass x gravitational accelerationOr weight = weight on earth x specific gravity Now see if you can figure it outW= 100 lbs x .17=17 lbs.

Law 3

• For every action there is an _____________and _______________ re-action.

• http://teachertech.rice.edu/Participants/louviere/Newton/law3.html

Sir Isaac Newton1642-1727

Newton in a nutshellWithout the influence of ____________,

planets would move in a straight line out into space.

The tendency of planets to remain in a straight line and the force of ________________ result in elliptical patterns

Using Newton’s gravity

Basically Force is proportional to the product of the mass

of two objects/distance between them squared so:

If the mass doubles the force ____________ but if the distance doubles then you have ________ the force.

So you can figure weight of an object if you know the distance from earth


2.7 Newton’s LawsGravity

On the Earth’s surface, __________________

_________________ is approximately constant, and directed toward the center of Earth


2.7 Newton’s LawsGravity

The constant G is called the ______________________________________; it is measured experimentally and found to be

G = 6.67 x 10-11 N m2/kg2


But let’s look at an easier way

Fgm1m2/d2

The force of gravity is proportional to the product of the mass of the two objects divided by the distance squared

White board problem

If Marvin is 36 lbs how much is his weight if he is at 2r (distance from Earth)

Weight = 36/22 36/4=9lbs

So if this is true and astronauts at the space station are still within the

earth’s gravity, why do they experience

weightlessness???http://www.youtube.com/watch?

v=2V9h42yspbo


2.8 Newtonian Mechanics

_________________: the speed necessary for a projectile to completely escape a planet’s _________________________________. With a lesser speed, the projectile either returns to the planet or stays in orbit.

So what did Einstein have to say about gravity?But what is gravity, what is it that attracts to objects to one

another? http://www.youtube.com/watch?v=O-p8yZYxNGchttp://www.youtube.com/watch?

v=DbhuRcmSkMg&feature=related

Gravity as Curved Space

Curved space

• Einstein noticed ___________________. A beam of light follows the curvature of space

• Planets follow the _________________so if gravity has curvature then anything with

mass will curve the space around it

Documents

2011 Pearson Education, Inc. Units of Chapter 2 2.1 Ancient Astronomy 2.2 The Geocentric Universe 2.3 The Heliocentric Model of the Solar System The