The Solar System
ASTR 1010
Tu/Th 12:30-1:45PM, Room 202
by Inseok Song
Lecture #1
Physics / Astronomy “majors”…
go out and see Mr. Tom Barnello (Room 310)
to be enrolled in ASTR1110 instead!
I am an exo-planet hunter!
1st Imaged Exo-planetary system !
… trying to understand the origin of planetary systems
• In Pleiades, collision between two
planets!
Gemini Planet Imager (GPI)
• The largest scale exoplanet
imaging project in the world.
o 1000 hrs of “clear” observing time
with the 8m telescope
o 34 million USD for manufacturing 
highly specific instrument for
exoplanet imaging
o will observe about 1,000 nearby
stars to image orbiting planets
about $34,000 / star
o Need to prepare the best set of
targets
• I am the leader of the target
selection group for GPI
First Day of the Class
• Professor: Inseok Song
• Office : Physics Building, Room 240
Office Telephone Number: 706-542-7518
• E-Mail Address: song@uga.edu
• Course Webpage:
http://cosmos.physast.uga.edu/iSong/ASTR1010
• Office Hours: Tue/Thu after the class or by appointment
Check the course webpage frequently!
http://www.physast.uga.edu  “course schedule”  ASTR1010
Why Astronomy?
“… it is better to be a human being dissatisfied than a pig satisfied”
- John Stuart Mill, 19th century British philosopher
beautiful
extreme
curiosity
past
future
Vast Universe
Vast Universe
Hubble Ultra Deep Field: in a very small region of the sky (similar to the
angular extent of a penny at the end of a football field), ~10,000 galaxies
were found.
Vast Universe : Hubble Ultra Deep Field
In the Universe, there are about 10 billions galaxies!
And, each galaxy has about the same number of stars as in the Milky Way
So, there have to be Earth-like planets somewhere out there…
Yet, we are barely reaching out the boundary of Solar System with our technology
It is very difficult to explore distant space, let’s first know the details of our Backyard!
Astronomy
• To understand the Universe, astronomers are using scientific methods.
Characteristics of Science
1. Collection of facts (or observations)
2. Create/test a model to explain observations
3. Make a testable prediction
4. After successful predictions, it becomes a theory
models  should be as simple as possible.  Occum’s razor
examples: a model of the atom, a model of the solar system…
Through numerous tests/verifications, theory becomes law.
Pseudo-Science
Pseudo-science : handling the nature appearing as a true science, but it involves a
non-scientific handling of evidence or method.
(Ex) Biorythm: every human being has three distinct cycles (physical: 23 days,
emotional: 28 days, intellectual: 33 days) which determine the fate of an
individual.
Scientific… in your daily life
fact 
skepticism 
test 
draw a new conclusion 
Say that you are looking for a used car, and you
are offered a lovely, 1-year old Porsche for
just $500.
?Why should the price so low?
?Does the car run?
?Has it been wrecked and poorly rebuilt?
Ask your friend
Take a test drive
Get examined by a mechanic you trust
being scientific : skeptical and looking for
greater confidence in a drawing conclusion.
Tentativeness : Being “Scientific” is not absolute!
• 200 years ago, French Academy of
Science declared that the notion of
stones falling from the sky (e.g.,
meteorites) by Chladni is not
scientific; a complete nonsense.
why? Scientific evidence for this
hypothesis (claim) is lacking…
Then, the claim by Ernst Chladni
received a spectacular
confirmation by a prominent
meteor shower near L’Aigle, France
in 1803.
Scientific or not?
? Thanks to Isaiah Crowell, UGA will win the season opening game against
Boise State on Sep 3, 2011.
? Terrestrial bacteria can survive on Mars.
? A huge fleet of alien ships will land on Earth and introduce an era of peace
and prosperity on January 1, 2020.
? There is no liquid water on the surface of Venus today.
? My house is haunted by ghosts, who makes the creaking noises I hear each
night.
? God created the Universe with all Laws of Nature (e.g., Law of Motion,
evolution, etc)
Logic and clarity are the most important!
Does not matter if it is right or wrong!
Laws of Physics
• Proven physical theories that survived numerous tests over time are
referred to as “Laws of Physics”
these can have profound effect on civilization.
“Newtonian Theory of Gravity” or “Newtonian Mechanics”
 immediate practical application in the construction of machines, buildings,
bridges, etc.
Theoretical and mathematical advances triggered by Astronomy
led to the Industrial Revolution.
Formation of the solar system
• By exploring the planets in our solar system, we can uncover the clues to
the origin of the Solar System.
o Solar System = the Sun and all celestial objects orbiting the Sun (planets, moons,
asteroids, comets, and more)
o From accumulated knowledge from various space missions in addition to the
Moon rocks brought back by Apollo mission, we now know that our Solar System
has been shaped by numerous collision among its constituents.
o Age of the Solar System: How do we know?
 the oldest rocks on the Earth  3.9 billion years old (3.9 Gyr)
 oldest object found on Earth  4.56 Gyr meteorites
 deduced the age of Solar System to be ~4.56Gyr
Stars are born, age, and die
• By studying stars, astronomers discover how stars are born, age, and die.
What powers stars?
Forming Stars (massive star formation site)
Orion Nebula (about 400 parsecs or 1300 Lyrs away)
Exploded star
Crab nebula
(supernova seen
in 1054 AD)
about 6000 Ly away
From galaxies to the Universe
• By observing galaxies,
astronomers learn about
the origin and fate of the
universe
o all galaxies are moving away
from us and from each other
 expanding Universe
Big Bang
(Right) Image of a star and a
quasar that are drastically
different in nature.
star : ~100 Ly away
quasar : 9 billion Lyr away
In summary…
Important Concepts
Important Terms
• Science
•
•
•
•
•




observables
hypothesis
testable prediction
theory
Occum’s razor
Laws of Physics
Nebula
Nuclear burning (or H-burning)
quasar
Chapter/sections covered in this lecture : sections 1.1-1.4