History of Astronomy
Question of the Day
Question: What is your grade in ESS?
Answer: … … …
Frequently Missed Test Questions
Our galaxy is classified as a(n)
a. Irregular galaxy
b. Elliptical galaxy
c. Spherical galaxy
d. Spiral galaxy
Frequently Missed Test Questions
Light traveling towards you will be red
shifted due to the Doppler Effect.
a. True
b. False
Frequently Missed Test Questions
Spiral galaxies often appear bluish due to an
abundance of
a. Old stars
b. Black holes
c. Young stars
d. White dwarfs
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History of Astronomy
Or, how did we build our current
understanding about the solar
system?
An interest starts….

Since ancient times, astronomers
observed the skies, watching the paths of
the planets and stars

Observations of Mars started philosophers and
astronomers trying to explain the motion of the
planet across the sky
An Interest starts…
Mars usually moves from east to west compared to
the stars, but occasionally it changes directions
(retrograde motion)

Which step of the Scientific Method is this?
A.
B.
C.
D.
Hypothesis
Drawing Conclusions
Observing/ Stating a problem
Experiment
Aristotle’s Hypothesis
Very influential Greek philosopher
 Lived approximately 350 B.C.
 Thought the universe
consisted of concentric
spheres

Aristotle’s Hypothesis

Aristotle believed the universe was
geocentric. This means that
A.
B.
C.
D.
The earth was at the center
The sun was at the center
A black hole was at the center
A galaxy was at the center
Ptolemy’s Hypothesis




QuickTime™ and a
GIF decompressor
are needed to see this picture.

Approximately 150
A.D
Geocentric Model
Lived in Egypt,
influenced by
Greeks
Planets moved on a
small circle that
moves on the
circumference of the
planet’s orbit
Model lasted for
over 1000 years
Ptolemey’s
Model
Copernicus’ Hypothesis


1473 - 1543
Revived an old Greek heliocentric
model. This model was centered around
A.
B.
C.
D.

The earth
The sun
A black hole
A galaxy
Only slightly better predictions of
planet’s positions because orbits were
still perfect circles
Galileo Galilei


1600
Used telescope to
observe
A.
B.
C.
D.



UFOs
The Sun
moons of Jupiter
Life on Mars
Confirmed Copernicus’
findings
House arrest for beliefs
Church finally
apologized in 1970’s
Tycho Brahe





Eccentric Danish nobleman,
astronomer to the Danish King
Had a silver nose from a duel
Geo-Helio-Centric model
Hired a young mathematician
to help with observations and
calculations- Kepler.
When Tycho dies, Kepler took
research and precise
measurements from him.
Brahe’s
Model
Kepler’s Hypothesis


Used Brahe’s data
Correctly modeled the
orbit of the planets
but had difficulty
believing his own
work
Kepler’s Three Laws
Law #1: All planets orbit
the Sun in ellipses.
Before Kepler, everyone
assumed that planetary orbits
were circular. By studying
Mars, Kepler realized that this
was not true.
Law #2: Planets move
faster when they are
closer to the Sun and
slower when they are
further away.
The imaginary line between
the planets and the Sun sweep
out equal areas in equal times.
Law #3: The further the
distance from the Sun, the
longer the “year.”
The period of a planet’s orbit
around the Sun is determined
by its distance from the Sun.
http://www.lasalle.edu/~smithsc/Ast
ronomy/retrograd.html
p. 550, #1-5
1.
1.
List the planets in order of their distance from the sun.
The planets in order of their distance from the sun are Mercury, Venus,
Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. [Pluto is now a dwarf
planet, FYI.]
2.
2.
Explain why the surface of Venus is hotter than the surface of Mercury.
The surface of Venus is hotter than the surface of Mercury because Venus’s
atmosphere causes a greenhouse effect.
3. Describe some of the geologic features on Mars.
3.Some of the geologic features on Mars are volcanoes, mountain systems,
canyons, and polar ice caps.
p. 550, #1-5
4. Compare the inner planets with the outer planets.
4. The inner planets are small and have solid, rocky surfaces. The outer planets,
except for Pluto, are larger than the inner planets are and have thick gaseous
atmospheres. They also have solid surfaces.
5. Describe the origin of the planets.
5. The planets were formed out of the cloud from which the sun condensed.