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ASTRO 101
ASTRO 101
Instructor: Jerome A. Orosz (rhymes with boris) Contact:
Instructor: Jerome A. Orosz (rhymes with boris) Contact:
Text: Discovering the Essential Universe, Fifth Edition by Neil F
Text: Discovering the Essential Universe, Fifth Edition by Neil F
Course WWW Page
Course WWW Page
Astronomy Help Room
Astronomy Help Room
Homework
Homework
Homework
Homework
Next:
Next:
A Brief History of Astronomy
A Brief History of Astronomy
Stonehenge (c
Stonehenge (c
The great pyramids of Egypt were aligned north-south
The great pyramids of Egypt were aligned north-south
A Brief History of Astronomy
A Brief History of Astronomy
A Brief History of Astronomy
A Brief History of Astronomy
A Brief History of Astronomy
A Brief History of Astronomy
What is a model
What is a model
Aristotle (385-322 B.C.)
Aristotle (385-322 B.C.)
Geocentric Model
Geocentric Model
Geocentric Model
Geocentric Model
This is the constellation of Orion
This is the constellation of Orion
The constellations rise and set each night, and individual stars make
The constellations rise and set each night, and individual stars make
Geocentric Model
Geocentric Model
Planetary Motion
Planetary Motion
Planetary Motion
Planetary Motion
Aristotles Model
Aristotles Model
Better Predictions
Better Predictions
Ptolomys Epicycles
Ptolomys Epicycles
Ptolomys Epicycles
Ptolomys Epicycles
Ptolomys Epicycles
Ptolomys Epicycles
Ptolomys Epicycles
Ptolomys Epicycles
The Middle Ages
The Middle Ages
Next:
Next:
The Sun-Centered Model
The Sun-Centered Model
The Sun-Centered Model
The Sun-Centered Model
The Sun-Centered Model
The Sun-Centered Model
The Sun-Centered Model
The Sun-Centered Model
Copernican Model
Copernican Model
Tycho Brahe (1546-1601)
Tycho Brahe (1546-1601)
Tycho
Tycho
Johannes Kepler (1571-1630)
Johannes Kepler (1571-1630)
Johannes Kepler (1571-1630)
Johannes Kepler (1571-1630)
Keplers Three Laws of Planetary Motion
Keplers Three Laws of Planetary Motion
Keplers Three Laws of Planetary Motion
Keplers Three Laws of Planetary Motion
Ellipses
Ellipses
Ellipses
Ellipses
Keplers Three Laws of Planetary Motion
Keplers Three Laws of Planetary Motion
Keplers Three Laws of Planetary Motion
Keplers Three Laws of Planetary Motion
Keplers Second Law
Keplers Second Law
Keplers Three Laws of Planetary Motion
Keplers Three Laws of Planetary Motion
Keplers Three Laws of Planetary Motion
Keplers Three Laws of Planetary Motion
Keplers Third Law
Keplers Third Law
The Keplers Law Simulator
The Keplers Law Simulator
Heliocentric or Geocentric
Heliocentric or Geocentric
Heliocentric or Geocentric
Heliocentric or Geocentric
Heliocentric or Geocentric
Heliocentric or Geocentric
Next:
Next:
Galileo Galilei (1564-1642)
Galileo Galilei (1564-1642)
Galileo Galilei (1564-1642)
Galileo Galilei (1564-1642)
Jupiters Moons
Jupiters Moons
Jupiters Moons
Jupiters Moons
Jupiters Moons
Jupiters Moons
Venus
Venus
Venus
Venus
Venus
Venus
Venus
Venus
Venus
Venus
Venus in the Geocentric View
Venus in the Geocentric View
Venus in the Heliocentric View
Venus in the Heliocentric View
Venus in the Heliocentric View
Venus in the Heliocentric View
Galileos observations of Jupiter and Venus strongly favored the
Galileos observations of Jupiter and Venus strongly favored the
Galileos observations of Jupiter and Venus strongly favored the
Galileos observations of Jupiter and Venus strongly favored the
Galileos observations of Jupiter and Venus strongly favored the
Galileos observations of Jupiter and Venus strongly favored the

: ASTRO 101. : Jerome Orosz. : ASTRO 101.ppt. zip-: 1823 .

ASTRO 101

ASTRO 101.ppt
1 ASTRO 101

ASTRO 101

Principles of Astronomy

2 Instructor: Jerome A. Orosz (rhymes with boris) Contact:

Instructor: Jerome A. Orosz (rhymes with boris) Contact:

Telephone: 594-7118 E-mail: orosz@sciences.sdsu.edu WWW: http://mintaka.sdsu.edu/faculty/orosz/web/ Office: Physics 241, hours T TH 3:30-5:00

3 Text: Discovering the Essential Universe, Fifth Edition by Neil F

Text: Discovering the Essential Universe, Fifth Edition by Neil F

Comins

4 Course WWW Page

Course WWW Page

http://mintaka.sdsu.edu/faculty/orosz/web/ast101_fall2012.html Note the underline: ast101_fall2012.html Also check out Nick Strobels Astronomy Notes: http://www.astronomynotes.com/

5 Astronomy Help Room

Astronomy Help Room

No appointment needed!

Just drop by!

Where: Room 215, physics-astronomy building.

When:

Monday: 12-2, 4-6 PM Tuesday: 12-1 PM; 4-6 PM Wednesday: 12-2, 5-6 PM Thursday: 4-6 PM

6 Homework

Homework

Homework due September 18: Question 11 from Chapter 2 (In what ways did the astronomical observations of Galileo support a heliocentric cosmology?) Write down the answer on a sheet of paper and hand it in before the end of class on September 18.

7 Homework

Homework

Go to a planetarium show in PA 209: Wednesday, September 12: 12:00 PM -- 12:30 PM Thursday, September 13: 12:00 PM 12:30 PM AND 12:30 PM 1:00 PM Friday, September 14: 12:00 PM 12:30 PM AND 12:30 PM 1:00 PM Monday, September 17: 12:00 PM 12:30 PM AND 12:30 PM 1:00 PM Thursday, September 20: 12:00 PM 12:30 PM AND 12:30 PM 1:00 PM AND 4:00 PM 4:30 PM Friday, September 21: 12:00 PM 12:30 PM AND 12:30 PM 1:00 PM Get 10 points extra credit for homework part of grade. Sign up for a session outside PA 209. Hand in a sheet of paper with your name and the data and time of the session.

8 Next:

Next:

The motion of the planets

9 A Brief History of Astronomy

A Brief History of Astronomy

10 Stonehenge (c

Stonehenge (c

2000 B.C.)

Stonehenge was probably used to observe the sun and Moon. Image from FreeFoto.com

11 The great pyramids of Egypt were aligned north-south

The great pyramids of Egypt were aligned north-south

12 A Brief History of Astronomy

A Brief History of Astronomy

An early view of the skies: The Sun: it rises and sets, rises and sets The Moon: it has a monthly cycle of phases. The fixed stars: the patterns stay fixed, and the appearance of different constellations marks the different seasons. Keep in mind there were no telescopes, no cameras, no computers, etc.

13 A Brief History of Astronomy

A Brief History of Astronomy

But then there were the 5 planets: These are star-like objects that move through the constellations. Mercury: the fastest planet, always near the Sun. Venus: the brightest planet, always near the Sun. Mars: the red planet, slower than Venus. Jupiter: the second brightest planet, slower than Mars. Saturn: the slowest planet.

14 A Brief History of Astronomy

A Brief History of Astronomy

By the time of the ancient Greeks (around 500 B.C.), extensive observations of the planetary positions existed. Note, however, the accuracy of these data were limited. An important philosophical issue of the time was how to explain the motion of the Sun, Moon, and planets.

15 What is a model

What is a model

A model is an idea about how something works. It contains assumptions about certain things, and rules on how certain things behave. Ideally, a model will explain existing observations and be able to predict the outcome of future experiments.

16 Aristotle (385-322 B.C.)

Aristotle (385-322 B.C.)

Aristotle was perhaps the most influential Greek philosopher. He favored a geocentric model for the Universe: The Earth is at the center of the Universe. The heavens are ordered, harmonious, and perfect. The perfect shape is a sphere, and the natural motion was rotation.

17 Geocentric Model

Geocentric Model

The motion of the Sun around the Earth accounts for the rising and setting of the Sun. The motion of the Moon around the Earth accounts for the rising and setting of the Moon. You have to fiddle a bit to get the Moon phases.

18 Geocentric Model

Geocentric Model

The fixed stars were on the Celestial Sphere whose rotation caused the rising and setting of the stars.

19 This is the constellation of Orion

This is the constellation of Orion

20 The constellations rise and set each night, and individual stars make

The constellations rise and set each night, and individual stars make

a curved path across the sky. The curvature of the tracks depend on where you look.

21 Geocentric Model

Geocentric Model

The fixed stars were on the Celestial Sphere whose rotation caused the rising and setting of the stars. However, the detailed motions of the planets were much harder to explain

22 Planetary Motion

Planetary Motion

The motion of a planet with respect to the background stars is not a simple curve. This shows the motion of Mars. Sometimes a planet will go backwards, which is called retrograde motion.

23 Planetary Motion

Planetary Motion

Here is a plot of the path of Mars. Other planets show similar behavior.

Image from Nick Strobel Astronomy Notes (http://www.astronomynotes.com/)

24 Aristotles Model

Aristotles Model

Aristotles model had 55 nested spheres. Although it did not work well in detail, this model was widely adopted for nearly 1800 years.

25 Better Predictions

Better Predictions

Although Aristotles ideas were commonly accepted, there was a need for a more accurate way to predict planetary motions. Claudius Ptolomy (85-165) presented a detailed model of the Universe that explained retrograde motion by using complicated placement of circles.

26 Ptolomys Epicycles

Ptolomys Epicycles

By adding epicycles, very complicated motion could be explained.

27 Ptolomys Epicycles

Ptolomys Epicycles

Image from Nick Strobels Astronomy Notes (http://www.astronomynotes.com/).

28 Ptolomys Epicycles

Ptolomys Epicycles

29 Ptolomys Epicycles

Ptolomys Epicycles

Ptolomys model was considered a computational tool only. Aristotles ideas were true. They eventually became a part of Church dogma in the Middle Ages.

30 The Middle Ages

The Middle Ages

Not much happened in Astronomy in the Middle Ages (100-1500 A.D.).

31 Next:

Next:

The Copernican Revolution

32 The Sun-Centered Model

The Sun-Centered Model

Nicolaus Copernicus (1473-1543) proposed a heliocentric model of the Universe. The Sun was at the center, and the planets moved around it in perfect circles.

33 The Sun-Centered Model

The Sun-Centered Model

The Sun was at the center. Each planet moved on a circle, and the speed of the planets motion decreased with increasing distance from the Sun.

34 The Sun-Centered Model

The Sun-Centered Model

Retrograde motion of the planets could be explained as a projection effect.

35 The Sun-Centered Model

The Sun-Centered Model

Retrograde motion of the planets could be explained as a projection effect.

Image from Nick Strobels Astronomy Notes (http://www.astronomynotes.com/)

36 Copernican Model

Copernican Model

The model of Copernicus did not any better than Ptolomys model in explaining the planetary motions in detail. He did work out the relative distances of the planets from the Sun. The philosophical shift was important (i.e. the Earth is not at the center of the Universe).

37 Tycho Brahe (1546-1601)

Tycho Brahe (1546-1601)

Tycho was born in a very wealthy family. From an early age, he devoted himself to making accurate astronomical observations. He received a great deal of support from the king of Denmark, including the use of his own island.

38 Tycho

Tycho

Tycho lived before the invention of the telescope. His observations of Mars were about 10 times more accurate than what had been done before.

39 Johannes Kepler (1571-1630)

Johannes Kepler (1571-1630)

Kepler was a mathematician by training. He believed in the Copernican view with the Sun at the center and the motions of the planets on perfect circles. Tycho hired Kepler to analyize his observational data.

40 Johannes Kepler (1571-1630)

Johannes Kepler (1571-1630)

Kepler was a mathematician by training. He believed in the Copernican view with the Sun at the center and the motions of the planets on perfect circles. Tycho hired Kepler to analyize his observational data. After years of failure, Kepler dropped the notion of motion on perfect circles.

41 Keplers Three Laws of Planetary Motion

Keplers Three Laws of Planetary Motion

Starting in 1609, Kepler published three laws of planetary motion:

42 Keplers Three Laws of Planetary Motion

Keplers Three Laws of Planetary Motion

Starting in 1609, Kepler published three laws of planetary motion: Planets orbit the Sun in ellipses, with the Sun at one focus.

43 Ellipses

Ellipses

An ellipse is a flattened circle described by a particular mathematical equation. The eccentricity tells you how flat the ellipse is: e=0 for circular, and e=1 for infinitely flat.

44 Ellipses

Ellipses

You can draw an ellipsed with a loop of string and two tacks.

45 Keplers Three Laws of Planetary Motion

Keplers Three Laws of Planetary Motion

Starting in 1609, Kepler published three laws of planetary motion: Planets orbit the Sun in ellipses, with the Sun at one focus.

46 Keplers Three Laws of Planetary Motion

Keplers Three Laws of Planetary Motion

Starting in 1609, Kepler published three laws of planetary motion: Planets orbit the Sun in ellipses, with the Sun at one focus. The planets sweep out equal areas in equal times. That is, a planet moves faster when it is closer to the Sun, and slower when it is further away.

47 Keplers Second Law

Keplers Second Law

The time it takes for the planet to move through the green sector is the same as it is to move through the blue sector. Both sectors have the same area.

48 Keplers Three Laws of Planetary Motion

Keplers Three Laws of Planetary Motion

Starting in 1609, Kepler published three laws of planetary motion: Planets orbit the Sun in ellipses, with the Sun at one focus. The planets sweep out equal areas in equal times. That is, a planet moves faster when it is closer to the Sun, and slower when it is further away.

49 Keplers Three Laws of Planetary Motion

Keplers Three Laws of Planetary Motion

Starting in 1609, Kepler published three laws of planetary motion: Planets orbit the Sun in ellipses, with the Sun at one focus. The planets sweep out equal areas in equal times. That is, a planet moves faster when it is closer to the Sun, and slower when it is further away. (Period)2 = (semimajor axis)3

50 Keplers Third Law

Keplers Third Law

Period

P2

distance

d3

Mercury

0.241

0.058

0.387

0.058

Venus

0.615

0.378

0.723

0.378

Earth

1.000

1.000

1.000

1.000

Mars

1.881

3.538

1.524

3.540

Jupiter

11.857

140.588

5.203

140.852

Saturn

29.424

865.772

9.537

867.432

51 The Keplers Law Simulator

The Keplers Law Simulator

There are some animations on the web illustrating Keplers Laws: http://www.astro.utoronto.ca/~zhu/ast210/kepler.html

52 Heliocentric or Geocentric

Heliocentric or Geocentric

The year is around 1610. The old school is Aristotle and a geocentric view. The new school is the heliocentric view (Copernicus and Kepler). Which one is correct?

53 Heliocentric or Geocentric

Heliocentric or Geocentric

The year is around 1610. The old school is Aristotle and a geocentric view. The new school is the heliocentric view (Copernicus and Kepler). Which one is correct? Observational support for the heliocentric model would come from Galileo.

54 Heliocentric or Geocentric

Heliocentric or Geocentric

The year is around 1610. The old school is Aristotle and a geocentric view. The new school is the heliocentric view (Copernicus and Kepler). Which one is correct? Observational support for the heliocentric model would come from Galileo. Theoretical support for the heliocentric model would come from Isaac Newton.

55 Next:

Next:

Who Wins?

56 Galileo Galilei (1564-1642)

Galileo Galilei (1564-1642)

Galileo was one of the first to use a telescope to study astronomical objects, starting in about 1609. http://www.pacifier.com/~tpope/index.htm

57 Galileo Galilei (1564-1642)

Galileo Galilei (1564-1642)

Galileo was one of the first to use a telescope to study astronomical objects, starting in about 1609. His observations of the moons of Jupiter and the phases of Venus provided strong support for the heliocentric model.

58 Jupiters Moons

Jupiters Moons

The 4 objects circled Jupiter, and not the Earth!

59 Jupiters Moons

Jupiters Moons

You can watch Jupiters moons move from one side of Jupiter to the other in a few days.

60 Jupiters Moons

Jupiters Moons

Not all bodies go around the Earth!

61 Venus

Venus

Venus, the brightest planet, is never far from the Sun: it sets at most a few hours after sunset, or rises at most a few hours before sunrise.

62 Venus

Venus

Venus, the brightest planet, is never far from the Sun: it sets at most a few hours after sunset, or rises at most a few hours before sunrise. It is never out in the middle of the night.

63 Venus

Venus

Galileo discovered that Venus had phases, just like the Moon.

64 Venus

Venus

Galileo discovered that Venus had phases, just like the Moon. Furthermore, the crescent Venus was always larger than the full Venus.

65 Venus

Venus

Galileo discovered that Venus had phases, just like the Moon. Furthermore, the crescent Venus was always larger than the full Venus. Conclusion: Venus shines by reflected sunlight, and it is closer to Earth when it is a crescent.

66 Venus in the Geocentric View

Venus in the Geocentric View

Venus is always close to the Sun on the sky, so its epicycle restricts its position. In this view, Venus always appears as a crescent.

67 Venus in the Heliocentric View

Venus in the Heliocentric View

In the heliocentric view, Venus orbits the Sun closer than the Earth does. We on Earth can see a fully lit Venus when it is on the far side of its orbit.

68 Venus in the Heliocentric View

Venus in the Heliocentric View

The correlation between the phases and the size is accounted for in the heliocentric view.

69 Galileos observations of Jupiter and Venus strongly favored the

Galileos observations of Jupiter and Venus strongly favored the

heliocentric view of the Universe.

70 Galileos observations of Jupiter and Venus strongly favored the

Galileos observations of Jupiter and Venus strongly favored the

heliocentric view of the Universe. Galileo was put before the Inquisition and forced to recant his views.

71 Galileos observations of Jupiter and Venus strongly favored the

Galileos observations of Jupiter and Venus strongly favored the

heliocentric view of the Universe. Galileo was put before the Inquisition and forced to recant his views. Pope John Paul II admitted in 1992 that the Church was wrong to denounce Galileo.

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