Transcript History of Astronomy

Historical Astronomy
Ancient World
• Early Humans
questioned their
existence
• The Sun and moon
played huge roles in
early Astronomy
• Actually closer to
Astrology
Early Astronomy
• Dominated by
religious reasoning
• Mostly the Earth,
Moon, and Sun
• Gave most
occurrences religious
reasoning instead of
facts
Stonehenge
• Found in England
• Huge slabs of rocks in
a circle
• Used for summer and
winter solstice
ceremonies
• Still not sure who
made Stonehenge
Stonehenge
• Constructed 3000 – 1800
B.C.
• Alignments with locations of
sunset, sunrise, moonset and
moonrise at summer and
winter solstices
• Probably used as calendar.
Mayan Civilization
• Stars played a huge
role in the civilization
• Created massive
observatories
• Made their own
calendar
Mayan Calendar
• Ends December 21st
2012
Not the end of the world
Signifies a new era
“the golden era”
Mayan Observatories
Caracol (Maya culture, approx. A.D. 1000)
Classical Astronomy
Catholic Church
• Dominated Science
during Europe’s early
formation
• Regulated what
Astronomers studied
Pythagoras
• First recorded Greek
to believe that the
Earth was round
• Thought the sphere
was the most godly
shape
Aristotle
• Aristotle’s universe was Geocentric
– Geocentric means “Earth-centered”
• The Earth is at rest
– At the center of the Universe
• It is surrounded by 56 spheres
– rotating, perfect, concentric, crystalline
– 55 spheres for the Planets, Sun, Moon
– 1 sphere for the Stars
Aristotle
• Famous for his
“Round Earth” Theory
• EVIDENCE- During a
lunar eclipse he saw
Earth’s circular
shadow
Eratosthenes
• Famous Egyptian Experiment
• Measured the circumference of Earth
• Was within 200 miles
Eratosthenes (~ 200 B.C.):
Calculation of the Earth’s radius
Angular distance between
Syene and Alexandria ~ 70
Distance between Syene
and Alexandria ~ 5,000
stadia
Earth Radius ~ 40,000
stadia, which is probably ~
14 % too large – better than
any previous radius
estimate.
Theories of the Solar System
Geocentric model
• Focused on the Earth
being the center of the
universe
• With the planets and
sun moving around the
Earth
Ptolomy
• Believed the planets
moved around the
Earth in Epicycles
• Geocentric theory
Ptolomy Epicycle
Ptolomy’s
epicycle theory
Epicycles helped
Ptolomy explain
retrograde motion
Heliocentric model
Copernicus
• First Astronomer to
theorize that Earth was
revolving around the
sun = heliocentric
• Was not accepted until
after his death
• First book published
on the day of his
Death
The Copernican Revolution
Nicolaus Copernicus (1473 – 1543):
Heliocentric Universe (Sun in the Center)
New (and correct) explanation for
retrograde motion of the planets:
Retrograde
(westward)
motion of a
planet occurs
when the
Earth passes
the planet.
This made Ptolemy’s epicycles unnecessary.
Tycho Brahe
• Flamboyant and rich
Dutch astronomer
• Best planetary
observations
• Observed as a king’s
astronomer
Johannes Kepler
• Studied under
Tycho Brahe
• Used Tycho’s
observations to create
“The Laws of
Planetary Motion”
after Tycho’s death
Kepler’s 1st law
• All planets orbit around the
sun in an elliptical shape with
the sun at one foci
Eccentricities of Ellipses
1)
2)
e = 0.02
3)
e = 0.1
e = 0.2
5)
4)
e = 0.4
e = 0.6
Kepler’s Equal Area Law
• States that each planet
covers an equal area
during the same
amount of time
• Regardless of their
speed
2. AREA LAW
An imaginary line from
a Planet to the Sun
sweeps over equal
areas in equal
intervals of time
Pie slice analogy
The short wide
pieces have the
same amount
Of pie as the long
thin pieces
As long as they
represent “equal
times”!
Semimajor Axis
F1
Center
F2
T=0d
T=10d
T=0d
T=10d
Equal Areas in Equal Times
Kepler’s 3rd Law
• The period of time it takes for a planet to
orbit the sun is directly related to its
distance from the sun.
»
• P= period
• A= semi major axis
2
P
3
= A
Giordano Bruno
• First to consider stars
as other suns (exoplanets)
Burned at the stake for
heresy in 1600
Galileo Galilei
• First Astronomer to use a
telescope
• Telescope was invented
by Hans Lippershey in
1600
• Went blind later in life,
due to staring at the sun
through a telescope for too
long
• Church wasn’t happy with
him
Galileo Galilei
• Huge contributions to
Astronomy:
•
•
•
•
Jupiter’s moons
Moon features
Rings of Saturn
Sun Spots
• Strange experiments
Jupiter’s Moons
• First Astronomer to
view extraterrestrial
moons
• Able to see four
moons
Saturn’s Rings
• Galileo viewed
Saturn’s rings through
a telescope
• Galileo was the first
Astronomer to view
Saturn close up
Major discoveries of Galileo:
• Moons of Jupiter
(4 Galilean moons)
(What he really saw)
• Rings of Saturn
(What he really saw)
Major discoveries of Galileo (III):
• Sun spots (proving that the sun is not perfect!)
Major discoveries of Galileo (IV):
• Phases
of Venus, proving that Venus orbits the
sun, not the Earth!
Moon’s features
• Identified craters on
the moon
• Proposed that the
moon’s surface is
changing
Galileo’s finger
• On display at Institute and
Museum of History of Science
Florence, Italy
Isaac Newton
• Arguably the best
contributor to
modern science
• Defined the
Laws of Physics
The Apple Story
• Legend has it:
• As a young lad
Newton sat under an
apple tree and
observed an apple fall,
beginning his theories
of Physics
Contemporaries
Charles Messier (June 26, 1730 – April 12, 1817) was a
French astronomer, who published a catalogue of 110 deep sky
objects such as nebulae, galaxies, and star clusters.
M1
M31
Messier Catalogue – of space objects
Albert Einstein
• German scientist
• Modern Science
Genius, with very
complex theories
Einstein
• Developed theory of
relativity
• E = mc 2
• Universe shape
Theory
Stephen Hawkings
• Today’s foremost
Astrophysics thinker
• Teaches at Cambridge
University in England
• He is expanding on
Einstein’s theories
Soak it all in!