|
Front
|
Back
|
- the dog star
- "scorcher"
- brightest star in the night sky
- rising just before sun marks the beginning of summer
|
|
- (400 bc - 356 bc)1st recorded instance of a model describing (mathematically) the universe and the motions of the planets, started the idea of concentric speres
|
|
major authority of philosophy until late middle ages
- divided universe into 2 parts
- imperfect, changeable earth
- perfect havens (describes by spheres)
- expanded exodus' model to 55 spheres
- taught the earth is round
- why would he think that?
- they deduce that a lunar eclipse was a moon moving into the shadow of the earth
- Assertion that objects of different mass fall in diff speeds under gravity (wrong)
- held back science for 2000 years
- refuted democritus' claim milky way was multitude of stars
- refuted stars of night sky were just like the sun (wrong)
- calculated they would have to be millions of times farther away than sun
- thus dismissed for hundreds of years
-
|
|
- Greek mathematician, geographer and astronomer
- contemporaries nicknamed him beta (2nd letter of greek letter of alphabet) bc he was 2nd best at everything..
- ...need more?
|
|
access to babylonia observations and predictions
- used to create better geometrical models, constructed accurate models for movement of sun and moon
- moved earth from center of spheres
- compiled star catalogue
- recorded the position and brightness of the stars
- made magnitude system
- considers among most important greek astronomers (and greatest astronomer of antiquity by some)
- introduced the concept
@font-face {
font-family: "Wingdings";
}p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }div.Section1 { page: Section1; }ol { margin-bottom: 0in; }ul { margin-bottom: 0in; } of
exact prediction into astronomy last innovative astronomer before Ptolemy
@font-face {
font-family: "Wingdings";
}p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }div.Section1 { page: Section1; }ol { margin-bottom: 0in; }ul { margin-bottom: 0in; }
|
Hipparcus (2nd century bc)
|
compiled and extended the astronomical knowledge and theories of the ancient greek and babylonian world
- star catolog in almagest list 48 constellations
- ancestral to the modern system...
- geocentric (earth centered) model widely accepted until copernicus
- retrograde motion (reverses path)
- Epicycles
|
Ptolemy (c. 90 - c. 168 ad)
|
....... system was considered the "standard modle" of the universe until the copernican revolution
|
|
Copernican Revolution & beyond
99 years that changed our view of the Universe
Nicolaus Copernicus
Galileo Galilei
Tycho Brahe
Johannes Kepler
Isaac Newton
|
Copercican revolution and beyond
|
- one of the great renaissance polymaths(can do everything; math, astonomer..)
|
|
-
@font-face {
font-family: "Wingdings";
}p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }div.Section1 { page: Section1; }ol { margin-bottom: 0in; }ul { margin-bottom: 0in; }
arrived
at correct order of the known planets
n Explained
precession of the equinoxes correctly
n slow
change in the position of the Earth's rotational axis
n gave
a clear account of the cause of the seasons
n Earth's
axis not perpendicular to plane of orbit
n added
motion to Earth, keeping axis pointed throughout the year at the same place in
the heavens
- No center to universe
- Center of solar system near sun
- heliocentric (sun is center, wrong)
- Distance to sun imperceptible vs distance to stars
- Earths motion accounts for apparent motion
- rotation accounts for daily rotation of stars
- annual cycle of sun's movements caused by earths orbit
- apparent retrograde motion of planets is caused by orbit
- added motion to earth, keeping axis pointed throughout the year at the same place in the heavens=
- not experimentally better than ptolomys
|
|
- Italian
- physicist
- astronomer
- astrologer
- philosopher
- closely related with the scientific revolution
- improved (but did not invent) telescope
- invented the microscope
- observed the galilean moons
- motion indicated orbits about jupiter
- Observed rings of saturn
- observed full set of phases with venus
- One of the first Europeans to observe sunspots
- existence contradicted unchanging...
- Demonstrated equal acceleration of unequal masses
- Early example of science conflicting with church/authority
- 1633 - convicted of heresy
- required to recant heliocentric ideas
- idea that sun is stationary condemned as "formally heretical"
- helocentrism was never formally or officially condemned
- ordered imprisoned
- sentenced later commuted to house arrest
|
|
- preeminent observational astronomer of pre-telescopic period
- said to own 1% of Denmarks entire wealth as one
- observations of stellar/planetary positions unparalleled accuracy
- observations of nova contradicted immutable heavens
|
Tycho Brahe (1546 - 1602)
|
German
used observational table of brahe to study planetary motion mathematically
- consistent description by abandoning both,circular motion (bc planets do not move in circles) and uniform motion (bc planets do not move in constant speeds)
- believed that planets move around the sun on elliptical paths, with non-uniform vehicles
|
|
|
|
- 1. the orbits of the planets including the earth are ellipses with sun at one focus
- 2. a line from a planet to the sun sweeps over equal areas in equal intervals of time
- 3. A planets orbital period (P) squared is equal to the average distance from the sub (a) cubed (p^2 = 2^3)
- the period doesn't depend on how squashed the ellipse is (oval vs circle) it changes by the SIZE of the ellipse
|
Kepplers law math
if p = 170d
a = 0.6 au
find p
AND
if p = 75, find a
|
Some Math:
P^2=A^3
170 days
P = (170d)
a = 0.6 AU
P^2 = (o.6)^3 = 0.216
P = 0.46 years * 365 = 165 days
p = 165 days
MORE MATH :
P = 75
(75)^2 = a^3
5625 = a^3
5625^0.33 = a
a = 17.3 AU is how far haleys comet is on the average
|
+
