https://www.space.com/first-sun-image-from-massive-solar-telescope.html

Today

in

Space

News:

World's largest

solar telescope

produces never-

before-seen

image of our star

This is the

highest-resolution

photo of the sun

ever taken

Study Points• What did Copernicus do?

• What did Brahe contribute to the heliocentric vs. geocentric debate?

• Define perihelion and aphelion.

• Considering Kepler's three laws of planetary motion (don’t memorize them):

• What is the shape of a planet’s orbit? (First Law)

• When a satellite orbits the Earth, does it move faster at perigee or apogee? When a comet orbits the Sun, does it orbit faster at perihelion or at aphelion? (Second Law)

• Define period (from science)? In our solar system, what planet has the longest period? The shortest? Which planet orbits with the highest speed? Slowest? (Third Law)

• What did Galileo notice about the Moon, the Sun, Jupiter, and Venus? What did he conclude from these observations?

• Why does Venus exhibit phases but Mars does not? (Hint: Draw the Sun as well as Venus, Earth and Mars in their orbits. Shade in Venus and Mars. What do they look like from Earth’s view?)

• State Newton's Universal Law of Gravity. If the mass of 1 of the 2 objects increases, what happens to the gravitational force between the objects? If the distance between the 2 objects increases, what happens to the force?

• How can you tell if a process is science (what parts are needed)?

Copernican Revolution~1500 to ~1700

Copernican Revolution

People Who Contributed*

Copernicus (~1500)

Brahe (~1570)

Kepler (~1600)

Galileo (~1600)

Newton (~1670)

Copernican Revolution

Copernicus (~1500)

Resurrected heliocentric model*

and made it popular

First suggested by Aristarchus*

Copernican Revolution

Is solar system geocentric or heliocentric?*

Copernican Revolution

Both models have:

Circular orbits (heavenly perfection)

Uniform motion (heavens cannot change)

(Neither of these things are actually true!!)

Copernican Revolution

Both models explain observations…

Sun, Moon, &

Planets

Rise in the East,

Set in the West

Copernican Revolution

Both models explain observations…

Retrograde

motion of

planets

Copernican Revolution

Retrograde Motion – Geocentric

Planets ride on epicycles

Sometimes appear to move backwards

Copernican Revolution

Retrograde Motion – Heliocentric

• One planet overtakes

another planet.

• Slower planet appears to

move backwards.

Copernican Revolution

Copernicus (~1500)

Brahe (~1570)

Kepler (~1600)

Galileo (~1600)

Newton (~1670)

Copernican Revolution

Brahe (~1570)

• Built excellent instruments.*

• Collected 20+ years of data from

observations.*

• Measured position of Mars very

accurately.*

• Stayed with geocentric model.*

• Saw a supernova! (the sky changed)

Copernican Revolution

Copernicus (~1500)

Brahe (~1570)

Kepler (~1600)

Galileo (~1600)

Newton (~1670)

Copernican Revolution

Kepler (~1600)

Derived three mathematical

laws of planetary motion.

(from Brahe’s data)

Copernican Revolution

Kepler’s First Law

1. Planets have elliptical orbits around the Sun*Orbits are ellipses (squashed circles)*

PerihelionClosest point

to Sun*

AphelionFarthest point

from Sun*

>

<

Sun

Earth

Copernican Revolution

Kepler’s First Law

1. Planets have elliptical orbits around the Sun*

The Moon’s obit around Earth is also an ellipse.

perigee apogee

>

<

Earth

Moon

Copernican Revolution

Kepler’s First Law

1. Planets have elliptical orbits around the Sun*

All orbits can be described as ellipses.*

peri-apsis apo-apsis

>

<

Any object

Copernican Revolution

Kepler’s Second Law

2. The radius vector sweeps out equal areas in equal times.

Thirty

daysThirty

days

Radius

vector

<

>

>

Copernican Revolution

Kepler’s Second Law means that…

A planet changes speed*

- faster at perihelion, slower at aphelion*

Perihelion

(faster)

Aphelion

(slower)

Kepler’s Second Law

2. The radius vector sweeps out equal areas in equal times.

Copernican Revolution

Definition needed for

Kepler’s Third Law

Period = Time to complete one cycle*

Ex: Earth’s period of rotation =?

Ex: Earth’s period of revolution = ?

For Kepler’s law, we will use period of revolution

Copernican Revolution

Kepler’s Third Law

3. Period2 is proportional to (Radius of orbit)3

• Sometimes written as P2 α r3

• Bigger orbit radius means longer to revolve

• More distant planet takes more time to revolve.*

• More distant planet moves slower.* (slower speed in orbit)

• and

• Closer planet is faster and takes less time to revolve.

• http://physics.bu.edu/~duffy/HTML5/inner_solar_system_n

ew.html

Copernican Revolution

1. Planets have elliptical orbits around the Sun*

2. The radius vector sweeps out equal areas in equal times.• A planet changes speed*

3. Period2 is proportional to (Radius of orbit)3

• More distant planet takes more time to revolve.*

• More distant planet moves slower.*

Kepler’s 3 Laws

Copernican Revolution

Kepler’s Laws

Applies to any objects in orbit around a central mass

•Satellites around Earth

•Star around a black hole

•Planets around other stars

•Two stars orbiting each other

Copernican Revolution

Copernicus (~1500)

Brahe (~1570)

Kepler (~1600)

Galileo (~1600)

Newton (~1670)

Copernican Revolution

Meanwhile…

Out in the streets…

Galileo (~1600)

Improved and used the telescope(did NOT invent the telescope)

Copernican Revolution

Galileo observed…

1. Moon craters*

Heavens are not perfect*

Heavens are Earth-like!!!*

Copernican RevolutionArt and ideas flourished*

El Greco < 1600

Painted imperfect heavens

Cigoli – 1622

Painted

imperfect

cratered Moon

Copernican Revolution

Heaven is not

perfect!*

Galileo observes…

1. Moon Craters*

2. Sunspots* → Sun Rotates

Copernican Revolution

3. Galileo observes…

4 Moons

of Jupiter* Earth is

not the

ONLY

center of

motion in

the

heavens

Copernican Revolution

3. Galileo observes…

4 Moons

of Jupiter* ANDHey, Aristotle.

Earth can move

and pull the

Moon along.

Take that, Aristotle!

Copernican Revolution

4. Galileo Observes Phases of Venus*

• Geocentric model predicts:

• Crescent phase only and little size change

• Heliocentric predicts:

• All phases AND

• Gibbous is small, while crescent is large

Play Venus phases video

http://galileoandeinstein.physics.virginia.edu/more_stuff/flashlets/PhasesofVenus.htm

Copernican Revolution

4. Galileo Observes Phases of Venus*

http://astronomy.nmsu.edu/geas/lectures/lecture11/slide02.html

Copernican Revolution

Copernican Revolution

Galileo Observed*

1. Imperfect heavens, like Earth*

• Moon craters*

2. Sunspots*

3. Jupiter’s moons*

4. Phases of Venus*

Copernican Revolution

Copernicus (~1500)

Brahe (~1570)

Kepler (~1600)

Galileo (~1600)

Newton (~1670)

Copernican Revolution

Newton (~1700)

HOW planets orbit

(and objects move)

Same laws apply to terrestrial (Earth)

objects and celestial objects*

o called the Newtonian synthesis

o Means Earth and heavens are alike*

Copernican Revolution

Newton (~1700)

HOW planets orbit

(and objects move)

• Objects in orbit are continuously falling*

• Floating in space is really falling

(not due to zero gravity)

Copernican Revolution

Newton (~1700)

Copernican Revolution

Newton (~1700)

Three Laws of Motion (Not on test)

1. An object in motion remains in motion

unless acted on by an external force.

2. F=ma (Force = mass * acceleration)

3. Every action has an equal and opposite

reaction.

And

The Universal Law of Gravity*

Copernican Revolution

Newton - Universal Law of Gravity*

Every mass exerts a force on every other mass.

Note the UNIVERSAL statement.

m1 m2

F F

Copernican Revolution

Newton - Universal Gravity

Gravity always attracts*

Bigger mass means bigger force*

Bigger separation means smaller force*

m1 m2

F F

Copernican Revolution

Newton - Universal Gravity

2D

mMGF =

m M

F F

D

Copernican Revolution

Newton - Universal Gravity

m1 m2

F F

D

Side comments:

Predictability, Mechanistic universe

2D

mMGF =

Copernican Revolution

Copernican Revolution - Summary

Geocentric Vs. Heliocentric

Five people, contributions, significance

Copernicus (~1500)

Brahe (~1570)

Kepler (~1600)

Galileo (~1600)

Newton (~1670)

Process of science

A process of knowing that uncovers the laws and processes of the universe*

• Way to get past the conflicts in various belief systems (by looking at evidence)

• Differs from theology or philosophy because of the scientific method

Science

1. Observe

2. Question

3. Model (hypothesize)

4. Predict

5. Test

6. Revise

Process of Science*

(Scientific Method)

You use much of this process all the time in daily life

Examples: - Car stops….

- Flashlight doesn’t work…

- Cooking…

Three Hallmarks of Science*

• Natural explanations (not supernatural)

• Models that make testable predictions

• Simplest explanation; K.I.S.S. (Occam’s Razor)

Exercise

• Can you investigate this using science?

• If so, does science support the idea?

• If not, why not? (what hallmarks?)

Ex –

People get nuttier during a full Moon.

https://www.scientificamerican.com/article/lunacy-and-the-full-moon/

Observation Projects

• Planetarium (10 pts)

− Start: Jan 28

− Due: May 12

• Moon Phases (10 pts)

• Start Jan. 23

• Due March 5

• Sunset – Part 1 (10 pts)

• Start Jan. 21

• Due Feb. 18

• Star Gazing (20 pts)

• Start Jan 21

• Due May 12

• Moon Craters (10 pts)

− Start: Jan 30

− Due: May 12

• Telescope (20 pts)

• Start Jan. 30

• Due May 12

Homework• Continue STUDY POINTS

• Lab – no lab this week

• D2L Quizzes (#3 due today, #4 starts today)

• Test 1 next class: Tuesday, Feb. 11− To prepare: study points & 4 D2L quizzes

− About 40 multiple choice questions. Bring a pencil.

− Optional – bring a calculator (not graphing), some will be

in the room to use

− Astronomer writing assignment