Lecture 1 Astron 10 Instructor: Dr. Babar Ali

Lecture 1

Astron 10Instructor: Dr. Babar Ali

Fall 2013 Astro 103 2

Today’s Topics

I. Introductions

II. Organization of Classes

III. Course Syllabus

IV. Introduction to Astronomy & the Universe

I am so new …

• I do not yet have an e-mail

• 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

The Adjunct’s Office

Today’s Lecture

• No hardcopy of syllabus to hand out. • Actually copy of Syllabus will be handed out next lecture

on Thursday.


Syllabus

• Main points to be discussed today• Hardcopy at next lecture


Syllabus

Astronomy 1, Fall Semester, 2014

Instructor: Dr. Babar Ali Office: Center for the Sciences, adjuncts office

Office Hours: by appointment

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


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.


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.


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.


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.


Schedule of Lectures



Definition taken from the Oxford English Dictionary, Online Edition

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.


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.


The Size and Scale of the Universe


http://apod.nasa.gov/apod/ap120312.html

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.


Powers of Ten

• 1012 meters• Within the orbit

of Jupiter• About 5 AU

Powers of Ten

• 1013 meters• The solar system• About 40 AU

The Sun and Planets to Scale

1-1: By exploring the planets, astronomers uncover clues about the formation of the solar system

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

Approx. 17 light years

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:

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.

• Distance at which an object the size of 1 AU subtends 1 arc-seconds on the sky.


3.25 light years = 1 pc

Powers of Ten

• 1019 meters• The stars of the

Orion arm• 100s of parsecs

Stars like Grains of Sand

1-3: By studying stars and nebulae, astronomers discover how stars are born, grow old and die

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

A Galaxy

1-4: By observing galaxies, astronomers learn about the origin and fate of the universe

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


http://en.wikipedia.org/wiki/Observable_universe

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


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.


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?


The Nature of Science—Scientific Method

- Science is NOT a body of knowledge, but a method to understand nature & how it works

- Science accepts nothing on faith- The ultimate judge is always the experiment

Many OBSERVATIONS

over time

Scientific ideas are

HYPOTHESIS to explain the

observations

Test your hypothesis with, EXPERIMENT

Results CONTRADICT:

discard Hypothesis

Results AGREE w/prediction: Hypothesis

needs to survive more

experiments to be accepted as

a good description of

natureFor 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 64

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


Lecture 1 Astron 10 Instructor: Dr. Babar Ali

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