Today’s Comments D2L Quiz 3 & 4 available (#4 has first few questions from next lecture) Test 1 on Feb. 10. Special tutor session with Gustavo: Thurs,

Today’s Comments• D2L Quiz 3 & 4 available (#4 has first few questions from next lecture)• Test 1 on Feb. 10.

• Special tutor session with Gustavo: Thurs, Feb. 5, 3-5pm• Best test prep: 1. objectives, 2. D2L quizzes, 3. lectures/notes, 4.

book• Sunset – Part 1 Due Feb. 12 (in 2 weeks)

• Sunrise and Sunset times• http://www.timeanddate.com/sun/usa/minneapolis• Phone App: Sunrise Sunset

• Moon Phases Due Mar. 2 • Moon visible times: (Moonrise and Moonset)

• http://www.timeanddate.com/moon/usa/minneapolis• Phone App: Phases of the Moon Free

• Exploradome Planetarium Feb. 3 in T bldg plaza, 1st floor• 9am to 12pm – come for a 20-30 minute presentation, every half

hour. Shows at 9, 9:30, 10, 10:30, 11 and 11:30am.• Check-in with me. Counts for lecture that DAY & lab for the WEEK

Prior to the Copernican Revolution – Greek Astronomy

• Western only – Please investigate other cultures

• Greeks (influenced by Babylonia, Mesopotamia, Egypt, Rome)

• ~700 BC to ~140 AD• Some ideas and people

• Know the starred* items

Geocentric Model*(from Aristotle, 384-322BC)

Everything orbits around…

Earth Sun

Heliocentric Model* (from Copernicus, 1473-1543AD)

Prior to the Copernican Revolution – Greek Astronomy

~700 BC Early astronomy was about time keeping (when to sow and reap crops)

Prior to the Copernican Revolution – Greek Astronomy

Hesiad, Works and Days • ... when the Pleiades rise it is time to use the

sickle, but the plough when they are setting; 40 days they stay away from heaven; when Arcturus ascends from the sea and, rising in the evening, remain visible for the entire night, the grapes must be pruned;…

• Needed better observations to keep the various calendars synchronized.

Prior to the Copernican Revolution – Greek Astronomy

Greeks ~Fifth Century BC

• What is the sun? Fire?• Tiny lights in the sky?• Why do 7 lights wander

among the others? (7 Planetes*)

science.msfc.nasa.gov/ ssl/pad/solar/surface.htm

imagine.gsfc.nasa.gov/.../ news/22apr02.html

http://artsci.shu.edu/physics/1007/retro2.gif

Prior to the Copernican Revolution – Greek Astronomy

Pythagoras of Samos ~500 BC• Earth is a sphere• Sphere is perfection in math• Crystal spheres for 7 planetes

Sun, Moon, 5 others• Already thinking geocentric

http://library.thinkquest.org/C0126626/fate/geocentric.jpg

Prior to the Copernican Revolution – Greek Astronomy

Plato ~360 BC• Heavens are perfect, unchanging

(from mathematical perfection)• Heavenly motion must be in circles

and uniform

Prior to the Copernican Revolution – Greek Astronomy

Aristotle ~350 BC• Plato’s student• Earth: Corrupt, changeable, imperfect

(separation of heavens and Earth)• Arguments for geocentric model*

No parallax of stars*

and

Moon would be left behind*

• Parallax is the apparent change in position of an object due to the change in position of the observer– Parallax thumb demonstration

Prior to the Copernican Revolution – Greek Astronomy

Aristarcus ~300 BC• Heliocentric solar system

(first evidence)*• Measured size of Sun• Measured that Sun was much

further away than Moon

Prior to the Copernican Revolution – Greek Astronomy

Ptolemy ~140 AD• Geocentric model* (often called the

Ptolemaic system)• Mathematical model of universe*

– Perfect Bodies and orbits• circles,

spheres– Uniform motion– Epicycles*

(retrograde motion)*

From Moon LecturesAlready know this:• Minute to Minute: the Sun, Moon, stars, planets appear

to rise in East and set in West due to Earth’s spin (rotation).

• Day to Day: Moon moves West to East due to Moon’s orbit (revolution) around Earth.

New information:• Day to Day: Planets typically move West to East due to

their orbits around the Sun.• Retrograde Day to Day Motion: Planets move East to

West due to their orbits around the Sun and the difference in speeds of Earth and other planet.

Retrograde Motion (Day to Day)Sometimes planets moved backwards against the

background of stars.

Retrograde motion is East to West and observed day to day.

Minute to minute motion across sky is still East to West due to Earth’s rotation.

Mars’ Epicycle

PtolemyGeocentric ModelPerfect circles, spheres, uniform motion

Earth

Mars

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

•Retrograde (westward) motion of a planet occurs when the Earth passes the planet.

•Ptolemy’s epicylces unnecessary

Retrograde motion – HeliocentricNew (and correct) explanation of retrograde motion

of the planets.

Prior to the Copernican Revolution – Greek Astronomy

Dark Ages in Europe (5th to 15th centuries AD)

• Roman libraries sacked• Often violent mix of Latin and Arabic

cultures• Plague, famine, war • Islamic Golden Age of Science

Long time between Ptolemy ~140 AD to Copernicus ~1500 AD.

Summary

• Before Copernicus ~700BC to 140 AD

Geocentric Model Dominated– Pythagoras of Samos– Plato– Aristotle*– Aristarchus*– Ptolemy*

Observation Projects

OBSERVING PROJECTS (in order of due date) Each line below is worth 10 points for a total of 80 points.• Planetarium (Exploradome at MCTC): Feb. 3• Sunset – Part 1 Start: Jan. 20; Due: Feb. 12• Moon Phases Start: Jan. 22; Due: Mar. 3• Safe Sun Prep Work Start: Mar. 19; Due: Mar. 26+• Sunset – Part 2 Start: Apr. 2; Due: Apr. 28• Moon Craters Start: Jan. 29; Due: May 5• Star Gazing Start: Jan. 29; Due: May 5• Telescope Start: Jan. 29; Due: May 5

Observations• Star Gazing Observation

– Main Goal: See constellations in night sky

• Telescope Observation– Main Goal: Look at night sky through a telescope

• Moon Craters Observation– Main Goal: see Moon’s craters under magnification

• Jan. 29 to May 5 to complete• 7 Options for each of these 3 observations• Class website has more details.• Turn in verification sheet (unless you check-in with me at the

event).

6 Locations for Star Gazing, Telescopes & Moon Craters

• Options1. Eagle Lake Observatory at Baylor Regional Park (complete

star gazing and telescopes together and possible moon craters) - every other Sat. until Nov.• Easiest way to complete but about an hour drive & $5/car

2. Jackson Middle School Observatory (dates TBD) – Champlin, MN

3. Eisenhower Community Center (dates TBD) – Hopkins, MN 7-10pm (call 952-988-4070 for reservations)

4. University of MN (Fridays TBD) – Minneapolis, MN

5. Macalester College (Thursdays TBD) – St. Paul, MN

6. St. Thomas College (weeknights TBD) – St. Paul, MN

7th Option (at home) forStar Gazing, Telescopes &

Moon Craters• Star Gazing Observation

– Star gaze with friends and write a short report

• Telescope Observation– Use your/friends’ telescope and write a report (talk to

me)

• Moon Craters Observation– Use binoculars (from my office) and write short report

Star Gazing Observation• Main Goal: See constellations in night sky• Jan. 29 to May 5 to complete• 7 Possible Options

Must have an expert point out constellations OR write a report1. Eagle Lake Observatory at Baylor Regional Park (complete star

gazing and telescopes together and possible moon craters) – every other Sat. until Nov.• Best view and experience but about an hour drive & $5/car

2. Jackson Middle School Observatory (date TBD) – Champlin, MN3. Eisenhower Community Center (dates TBD) – Hopkins, MN 7-10pm

(call 952-988-4070 for reservations)4. University of MN (Fridays) – Minneapolis, MN5. Macalester College (Mondays or Thursdays) – St. Paul, MN6. St. Thomas College (weeknights TBD) – St. Paul, MN7. Star gaze with friends and write a short report

• Class website has more details.• Turn in verification sheet.

Telescope Observation• Main Goal: Look at night sky through a telescope• Jan. 29 to May 5 to complete• 7 Possible Options

1. Eagle Lake Observatory at Baylor Regional Park (complete star gazing and telescopes together and possible moon craters) - every other Sat. until Nov.• Best view and experience but about an hour drive & $5/car

2. Jackson Middle School Observatory (dates TBD) – Champlin, MN

3. Eisenhower Community Center (dates TBD) – Hopkins, MN 7-10pm (call 952-988-4070 for reservations)

4. University of MN (Fridays TBD) – Minneapolis, MN

5. Macalester College (Thursdays TBD) – St. Paul, MN

6. St. Thomas College (weeknights TBD) – St. Paul, MN

7. Use your/friends’ telescope and write a report (talk to me)

• Class website has more details.• Turn in verification sheet.

Moon Craters Observation• Main Goal: see Moon’s craters under magnification• Jan. 29 to May 5 to complete• 7 Possible Options (Must have visible Moon, ideal is half Moon)

1. Eagle Lake Observatory at Baylor Regional Park (complete star gazing and telescopes together and possible moon craters) - every other Sat. until Nov.• Best view and experience but about an hour drive & $5/car

2. Jackson Middle School Observatory (dates TBD) – Champlin, MN

3. Eisenhower Community Center (dates TBD) – Hopkins, MN 7-10pm (call 952-988-4070 for reservations)

4. University of MN (Fridays TBD) – Minneapolis, MN

5. Macalester College (Thursdays TBD) – St. Paul, MN

6. St. Thomas College (weeknights TBD) – St. Paul, MN

7. Use binoculars (from my office) and write short report

• Class website has more details.• Turn in verification sheet.