Lecture 1
Astron 10
Instructor: Dr. Babar Ali
Today’s Topics
I. Introductions
II. Organization of Classes
I. Course Syllabus
II. Introduction to Astronomy & the
Universe
Fall 2013
Astro 103
1
I am so new …
• I do not yet have an e-mail
The Adjunct’s
Office
• I just got a mailbox
• I do not have a phone extension
• I do not yet have access to the online system
• I do not have set office hours yet
Fall 2013
Astro 103
April, 2009
Today’s Lecture
• No hardcopy of syllabus to hand out.
• Actually copy of Syllabus will be handed out next lecture
on Thursday.
Fall 2013
Astro 103
April, 2009
Syllabus
• Main points to be discussed today
• Hardcopy at next lecture
Fall 2013
Astro 103
April, 2009
Syllabus
Astronomy 1, Fall Semester, 2014
Instructor: Dr. Babar Ali
office
Office Hours: by appointment
Office: Center for the Sciences, adjuncts
Contact Information: E-mail address: TBD
(This syllabus is adapted from one used by the department chair).
Goals
The whole of existence is vast and strange and unlike our life here on Earth. But one of the most
amazing things about the Universe is that we can understand it. The method that we use to
understand the Universe is called science, and this is a method that is open to everyone. Science is
not just for a couple of people in a university laboratory to use. What is more, science is not just for
finding out The Secrets of Creation either. It is something we all can use in our daily lives to
understand the world around us. This class will focus on just that: using science to understand the
world (and the Universe) around us.
Textbook
Jeffrey Bennett: The Cosmic Perspective
Fall 2013
Astro 103
April, 2009
Syllabus
Classroom Etiquette:
The whole purpose of many students coming together into one room for several hours a
week is to effectively learn a set of knowledge. Disruptive behavior stops other students
in the class from learning. Therefore, anything that disrupts other people from learning is
unacceptable. This includes coming in late, packing up/leaving early, talking, etc.
Cell Phones:
Cell phones are trouble no matter which class they’re in. I expect all cell phones to be off
and put away (no ring, no vibrate). If you are expecting an emergency call and speak to
me before class, you can sit by the door and leave the classroom to answer it.
Academic Misconduct
All instructors are required to report suspected cases of academic misconduct. See
Pierce’s Code of Student Conduct for the details. The most common forms of
misconduct in class are copying from another student (a neighbor; texting, etc.). While
students are highly encouraged to work together on homework, each student must turn in
their own assignment in their own words. Cases will be resolved by removal from the
class, a failing grade, and being reported to the Dean of Students for disciplinary action.
Fall 2013
Astro 103
April, 2009
Syllabus
Attendance
Attendance is expected and in a way will play a role in your final grade. While
attendance is necessary the entire semester, it is incredibly important during
the first three weeks. Because I am trying to separate the serious students
from the not-so-much during this time, anyone missing a day will be dropped
from the class and their seat given to someone on the lottery list waiting to join
the class. If someone has been dropped they can get onto the lottery list and
try and get back into the class. After the first three weeks, once the class has
settled down, this policy will be somewhat relaxed.
Just in general though, please consider that of the many astronomy professors
I have talked to, and the thousands of students that have passed through their
classes, they find that on average students that only show up for tests/quizzes
and to turn in homework get a full letter grade less than those that attend every
day.
Fall 2013
Astro 103
April, 2009
Syllabus
Grading
Your grade will be: 50% Final Exam, 25% Midterm, 20%
Homework, and 5% In-class participation.
The grade distributions will be:
A: >85%,
B: 70-84%,
C: 60-69%,
D: 50-59%,
F <50%.
So don’t panic if you get a 65% on a test.
Fall 2013
Astro 103
April, 2009
Syllabus
Midterm
The midterm will be an hour in length and be halfway through the semester. A green
book will be required for the midterm so make sure to bring one. The midterm will have 5
short-answer questions, and one more in-depth question and will take one hour. There
will be a 5 minute break following and the remaining time will be taken up with a short
lecture. I will give the graded midterms back to you in one week. You may then turn
them back into me one week after that with any additional work done. I will grade the
extra work and add one-half the points you gain to your midterm score. Example: a
midterm scores a 60% in-class. After a week working on it at home it is turned in and I
judge it to be 80% (a gain of 20 points). The score that is entered into my records for this
midterm is a 70%. I will post the solution to the midterm in the library so you can use it to
help study for the final exam.
Final Exam
The final exam is scheduled by the school administration and the date is available in the
schedule of classes not to mention the school paper. The final exam is cumulative. It is
double the midterm: double the worth, double the length, double the time. The final exam
will require a green book too. Unfortunately, because of the way finals week is
scheduled, students won’t be able to go back over their final.
Fall 2013
Astro 103
April, 2009
Schedule of Lectures
Fall 2013
Astro 103
April, 2009
Definition taken from the Oxford English Dictionary, Online Edition
Fall 2013
Astro 103
April, 2009
Modern Astronomy
• Is a science.
• It uses the scientific method to understand the nature of
the Universe.
– More about that shortly
• It is an application of the laws of physics to the Universe
beyond Earth.
– But, sometimes we use Earth as a reference.
• We assume the same laws of physics are applicable
everywhere in the Universe.
Fall 2013
Astro 103
April, 2009
What Astronomy Is NOT
• Must not to be confused w/ Astrology –
the belief system that states that people’s
destiny & human affairs are correlated to
the position of celestial objects in the
skies.
• Astrology does not use the scientific
method.
Fall 2013
Astro 103
April, 2009
The Size and Scale of the Universe
http://apod.nasa.gov/apod/ap120312.html
Fall 2013
Astro 103
April, 2009
Where are You?
To find our place among the stars, we will
zoom out from a familiar scene, to the
largest scales in the universe.
Powers of Ten
•
•
•
•
100 meters
One meter square
3.3 feet
A typical person is
about 1 m tall
Powers of Ten
•
•
•
•
101 meters
10 meters
33 feet
Size of a small part
of a park
Powers of Ten
• 102 meters
• 100 meters
• A large building.
Powers of Ten
•
•
•
•
103 meters
1000 meters = 1Km
About 0.67 miles
Golden Gate Park
Powers of Ten
• 104 meters
• 10 Km
• San Francisco
Powers of Ten
• 105 meters
• 100 Km = 67 miles
• The San Francisco
Bay area
Powers of Ten
• 106 meters
• 1000 Km
• California
Powers of Ten
• 107 meters
• North and Central
America
Powers of Ten
• 108 meters
• 67000 miles
• Earth is only
~8000 miles
Powers of Ten
• 109 meters
• Earth and Moon
Powers of Ten
• 1010 meters
• Orbit of the
moon within the
orbit of Earth
during four days
in July
Powers of Ten
• 1011 meters
• Orbits of Venus,
Earth, and Mars
• New Unit
• Astronomical
Unit
Earth Orbiting Around the Sun
In order to avoid large numbers beyond our
imagination, we introduce new units:
1 Astronomical Unit (AU)
= Distance Sun – Earth =
150 million km
Our Star, the Sun
The Sun
• The Sun is a typical star.
• Its diameter is about 1.39 million kilometers (roughly a
million miles).
• Its surface temperature is about 5500°C (10,000°F).
• A detailed scientific model of the Sun tells us that it
draws its energy from nuclear reactions occurring at its
center, where the temperature is about 15 million
degrees Celsius.
Fall 2013
Astro 103
April, 2009
Powers of Ten
• 1012 meters
• Within the orbit
of Jupiter
• About 5 AU
Powers of Ten
• 1013 meters
• The solar system
• About 40 AU
1-1: By exploring the planets, astronomers uncover
clues about the formation of the solar system
The Sun and Planets to Scale
Powers of Ten
• 1014 meters
• Our sun and the
orbits of its
planets
Powers of Ten
• 1015 meters
• Sol
Powers of Ten
• 1016 meters
• The Oort cloud
• 10,000+ AU
Powers of Ten
• 1017 meters
• The nearest stars
• About 1 Million AU
The Solar Neighborhood
New distance scale:
1 light year (ly) =
Distance traveled by light
in 1 year
= 63,000 AU = 1013 km
= 10,000,000,000,000 km
(= 1 + 13 zeros)
= 10 trillion km
Nearest star to the Sun:
Approx. 17 light years
Proxima Centauri, at a
distance of 4.2 light years
Powers of Ten
• 1018 meters
• Solar neighborhood.
Stars within 50 light
years
Parsec
• Distance measure used more often than light year.
3.25 light years = 1 pc
• Distance at which an object the size of 1 AU subtends 1
arc-seconds on the sky.
Fall 2013
Astro 103
April, 2009
Powers of Ten
• 1019 meters
• The stars of the
Orion arm
• 100s of parsecs
1-3: By studying stars and nebulae, astronomers
discover how stars are born, grow old and die
Stars like Grains of Sand
Powers of Ten
• 1020 meters
• Our spiral arm
Powers of Ten
• 1021 meters
• The Milky Way
Galaxy
• Diameter ~ 80,000
light years
Powers of Ten
• 1022 meters
• The Local
Group
1-4: By observing galaxies, astronomers learn about
the origin and fate of the universe
A Galaxy
Powers of Ten
• 1023 meters
• Within the Virgo
cluster
• Millions of parsecs,
or, Megaparsecs
Powers of Ten
• 1024 meters
• Clusters of galaxies
A Quasar
Powers of Ten
• 1025 meters
• Near the limit of our
knowledge
• 14 Gigaparsecs
Further readings
• Wikipedia:
• http://en.wikipedia.org/wiki/Observable_universe
Fall 2013
Astro 103
April, 2009
Sizes in the Universe
Review Topics
• How big is the observable Universe?
• What units of measurements are appropriate for
measuring sizes and distances for?
– Earth,
– Solar System
– Nearby Galaxies
– Universe
• What are the largest structures in the Universe?
• Rank them in order of size smallest to largest
– Custers of galaxies, Earth, Milky Way Galaxy, Solar
System, Moon, Sun
Fall 2013
Astro 103
April, 2009
Observing The Sky
• The previous slides show you our current understanding
of the Universe.
• Built on scientific research.
• Perspective: We “flew” through the Universe.
• But, in reality, our perspective is built from observations
made on Earth.
Fall 2013
Astro 103
April, 2009
1-5: Astronomers use angles to denote the positions
and apparent sizes of objects in the sky
Estimating Angles with Your Hand
The Small Angle Formula
A Telescope in Space
How Do We Know All This Stuff?
Fall 2013
Astro 103
April, 2009
The Nature of Science
—Scientific Method
-
Science is NOT a body of knowledge, but a method to
understand nature & how it works
Results
Science accepts nothing on faith
CONTRADICT:
discard
The ultimate judge is always the experiment
Many
OBSERVATIONS
over time
Hypothesis
Scientific ideas
are
HYPOTHESIS
to explain the
observations
Test your
hypothesis with,
EXPERIMENT
Results AGREE
w/prediction:
Hypothesis
needs to survive
more
experiments to
be accepted as
a good
description of
nature
For Astronomers, our laboratory is the Universe.
Astronomy is an Observational Science (test by observing samples of interest)
Astronomy is a Historical Science (what we observe has already happened)
Fall 2013
Astro 103
63
Key Ideas
• Astronomy, Science, and the Nature of the Universe: The
universe is comprehensible. The scientific method is a
procedure for formulating hypotheses about the universe.
Hypotheses are tested by observation or experimentation in
order to build consistent models or theories that accurately
describe phenomena in nature.
• Observations of the heavens have helped scientists discover
some of the fundamental laws of physics. The laws of physics
are in turn used by astronomers to interpret their observations.
• The Solar System: Exploration of the planets provides
information about the evolution of the solar system as well as
about the history and resources of Earth.
• Stars and Nebulae: Studying the stars and nebulae helps us
learn about the history and origin of the Sun and the solar
system
Key Ideas
• Galaxies: Observations of galaxies tell us about the origin and history
of the universe.
• Angular Measure: Astronomers use angles to denote the positions
and sizes of objects in the sky. The size of an angle is measured in
degrees arcminutes and arcseconds.
• Units of Distance: Astronomers use a variety of distance units.
These include the astronomical unit (the average distance from the
Earth to the Sun), the light-year (the distance that light travels in a
year), and the parsec.
See Online Textbook For More Review
Topics
Fall 2013
Astro 103
April, 2009