Astronomy 101
Astronomy

Course Introduction

Look up into the night sky. What do you see? How much of what you see can you describe? How many objects that you can describe are nearby the Earth? How many are extremely far away? Can you describe why the stars appear to rise and set daily and why we see different constellations during the course of a year? What, exactly, is a star anyway? Are the stars we see in the night sky part of our Milky Way, or do they belong to other galaxies? Perhaps the ultimate questions are: "How did we get here to be asking such things, and are there other intelligent beings seeking answers to similar questions?"

The study of astronomy, the study of objects and phenomena beyond the atmosphere of the Earth, takes us along an unending road of discovery. It is said that astronomy is the oldest science (which it is) and the youngest science (which it also is!). How can it be both? It is the oldest science in that mankind's attempts to understand the Universe began thousands of years ago with the tracking of the Sun, the Moon, and the seasons. It is the youngest science in that new discoveries are made everyday. New hypotheses must be formed that address these discoveries. As our technology advances—meaning larger telescopes, satellites, lightning-fast computers—so must our attempts to understand nature.

An advanced degree is not needed to participate actively in astronomy. You are involved by merely questioning what goes on beyond our home planet. A pair of binoculars, a star map, and curiosity will get you started. The next step will take you beyond visually wandering from constellation to constellation and will involve wanting to understand what you see, wanting to know how we know what we do. The next step is what you are taking by registering for this course.

This course is open to everyone, and there are no prerequisites. It is designed for students whose strengths lie in fields other than science or math. Having said that, we must note that mathematics is the language of the Universe, and there are some concepts that can be explained best and most thoroughly with a few equations. In all cases where mathematical formulae are involved, we give a review and examples of how to solve the problems.

Course Overview and Goals

What is Astronomy? As mentioned above, astronomy typically means the study of objects and phenomena beyond the atmosphere of the Earth. That is a lot of stuff! Astronomers today must and do specialize. The field of observational astronomy has been divided into roughly five disciplines: planetary sciences, solar physics, stellar astronomy, galactic/extra-galactic astronomy, and cosmology. Historically, the teaching of introductory astronomy has tried to cover all of these fields in 10 or 15 weeks! It should come as no surprise to find out that this approach has come under serious attack. The University of Washington has a separate planetary astronomy course, Astronomy 150, and plans are underway for developing a non-major extra-galactic and cosmology course as well. Each course covers a more limited amount of material, but covers it to greater depth. This course emphasizes topics on solar physics, stellar astronomy, and galactic astronomy. Hopefully, you, the student, will develop not only a solid foundation for future independent study but also a desire to take additional astronomy courses.

This course will introduce you to what it is that astronomers do. Today, our research consists of working with smaller questions contained within the largest question: "How does the Universe work?" We observe an astronomical object or event and note things that we do not understand. Can we figure it out within the basic physical and mathematical background that we have? If not, what additional observations are needed? We make measurements of the stars and other objects in our galaxy (and in other galaxies). After we make our observations, we must analyze the data. This usually means graphing the data and looking for relationships. (You will study in detail one of the most important graphs in astronomy, the Hertzsprung-Russell diagram, that led to our modern-day view of how stars evolve.) If we discover something that we believe will advance our knowledge of the Universe, even in a small way, we submit our results to a scientific journal for peer review and subsequent publication.

As you work through the lessons in this course, you will experience—as much as is possible over a short period of time—what it is like to be an astronomer. You start with learning the elementary physics and mathematics underlying our understanding of the Universe. From there you will step to the Sun and other stars and objects in the Milky Way. The lab exercises pace you through the types of measurements and analyses astronomers do, as well as give you practice in clear, concise writing of your results and your interpretation of them. The goal of the "Teacher's Corner" included with each lesson is to introduce current and future teachers to the astronomy education resources available on line. The inspiration for this follows one of NASA's priorities: "Educational Excellence: We involve the education community in our endeavors to inspire America's students, create learning opportunities, and enlighten inquisitive minds." In short, astronomy education is a "hot topic" today. The listings given at the end of each lesson have been chosen because of the quality of the material at each Web site.

Course Objectives

By the end of this course, you will be able to

• explain the concept of the celestial sphere and report on observations of objects in the night sky;
• connect terrestrial physics to astrophysics by demonstrating—with common, everyday materials—the concepts of conservation of momentum, angular momentum, energy, and the role that forces play in the Universe;
• discuss the nature of electromagnetic radiation and how that radiation transfers energy and information through interstellar space;
• show how the relative motion of a source of radiation and its observer can change the perceived wavelength of the radiation—and explain the importance of this phenomenon to astronomy in determining the motions of stars, the masses of stars, and the existence of extra-solar planets;
• summarize the overall properties of the various regions of the Sun; outline the process by which energy is produced in the Sun's interior; and explain how energy travels from the solar core, through the interior, and out into space;
• state how a Hertzsprung–Russell diagram is constructed, and summarize the properties of the different types of stars and the evolution of those stars identified by such a diagram;
• explain how the formation and life of a star is affected by its initial mass by contrasting the evolutionary histories of a high-mass and low-mass star;
• summarize the composition, physical properties, and characteristics of the interstellar medium—and describe the significance of the interstellar medium to the life cycle of stars;
• discuss the origin, components, and use of a distance-scale ladder in determining the distances to nearby stars as well as distant parts of the Galaxy; and
• relate the substructure and components of the Galactic disk to those of the Galactic halo and Galactic bulge.

Required Materials

Textbook (required):

• Voyages to the Stars and Galaxies (3rd edition) by Andrew Fraknoi, Sidney C. Wolff, David Morrison. 2004, International Thomson Publishing.
  
  This textbook was chosen for its readability. Not every topic will be covered, and some topics will be expanded upon through online lecture notes.

Lab Tools:

• simple scientific calculator
• 15 cm (6 inch) ruler
• small package of colored pencils or crayons

Lesson Format

Reading Assignments

Each lesson involves reading one or two chapters, occasionally an outside resource.

Lecture Notes with Self-review

Online lecture notes will serve to clarify certain harder-to-understand sections. They will also expand upon certain topics. These online notes also include self-review sections to check the comprehension level and to prepare the student for the exams.

Lab Exercises

The best way to learn astronomy is to do astronomy. Observational astronomers today take data, graph it, analyze it, and summarize their work. As much as possible, we have replicated this process in the lab exercises and have avoided a "cookbook" approach. Each lab will take approximately two or three hours to complete. You are encouraged to read completely through a lab before starting it. See what materials, review, additional reading, and responses are needed. Answers to some of the questions asked will not be found directly in the textbook or online notes. You are expected to piece together information and use your own logic to answer many questions.

Activities

Activities are similar to labs, but are much shorter, taking one-half to one hour to complete and generally focus on only one or two concepts.

Teacher's Corner

Most lessons include a list of Web sites with quality educational resources and lesson plans related to the concepts covered in that lesson.

Overview of Lessons

Lesson One

As incredible as it might sound, astronomy covers objects spanning sizes from the nucleus of an atom to the farthest reaches of the visible universe: from less than 1 picometer (10^–12 meter), to 10²⁶ meters, or equal to a full range of 38 powers of ten. Lesson One covers the major structures of the Universe and the basics of observing the night sky, including the vocabulary, and concludes with brief overview of the history of astronomy. At the end of Lesson One, you will complete your first lab assignment, "Distances in the Universe: The First Step"—within the online notes under Assignment 1: Finding the Size of the Earth and the Distances to the Moon and the Sun.

Lesson Two

What holds regions of the Universe together? Gravity. In Lesson Two, we set the physical foundations of astronomy, the laws that govern how everything moves and the forces involved. Chapter 2 of the textbook includes a brief history on how gravity was "discovered," and how we use the effect of one body upon another to determine mass. As part of Lesson Two, you will complete the first activity; you get to play with toys and discover the physics involved—the same physics that governs such things as the collapse of stars!

Lesson Three

Lesson Three is the next step in setting the foundation for observations. Here we cover the reasons for the seasons, time, phases of the Moon, eclipses, and tides. Each of these concepts has applications in planetary science, stellar astronomy, or both. The assignment for this lesson is an activity on the phases of the Moon. You perhaps have thought about the "dark side of the Moon," or the "far side of the Moon," but what do they mean? When the Moon is full at midnight on one side of the Earth, what is its phase 12 hours later, at midnight, on the opposite side of the Earth? This activity will help you answer these questions.

Lesson Four

Unlike most other scientists, astronomers cannot bring their test material into the laboratory for controlled experiments. To learn about our universe, we rely upon our knowledge of the nature of light: how it is produced, how it travels through a vacuum and through media, how it behaves when we "capture" it with a telescope. This lesson gives a survey of what we know about radiation, spectra, and telescopes. As part of this lesson, you will complete and submit the lab on spectral analysis, which covers emission, absorption, and continuous spectra.

Lesson Five

Our favorite star has to be the Sun. It is, by all accounts, just an average star, but extraordinary to us as a giver of life. This lesson covers two chapters in the textbook, starting first with the overall structure of the Sun and the Earth-Sun connection, and finishing with the nuclear powerhouse that rages in the core of the Sun. The activity that will be submitted as part of the lesson introduces the data we've obtained from the SOHO satellite, which has been monitoring the Sun continuously over the past few years. You will be calculating the tremendous velocity of a solar flare and the time it will take for the energy released to reach and affect Earth.

Lesson Six

Preparation for your midterm examination.

Lesson Seven

The backbone of stellar astronomy is the classification of stars and a chart called the Hertzsprung-Russell Diagram (H-R Diagram). The reading that accompanies this lesson introduces a lot of new vocabulary and concepts related to the classification of stars. There is ample self-review in the online notes to help you with this. The lab that will be completed as part of this lesson introduces the cosmic distance ladder; that is, the steps we take to calculate not only the distances to the nearest stars but also stairsteps from the bottom rungs to the edge of the visible universe. In this lab, we learn how we calculate distances using a method called "the spectroscopic parallax of stars." Here you use your knowledge of stellar spectra and the H-R Diagram to find the distances to stars in the constellation Leo.

Lesson Eight

In a metaphoric sense, stars are as much alive as we are. They are born in an environment that nourishes them until they mature enough to start fusion in their core. They may be alone, or part of a twin, triplet, or even multiple stellar system. Their birth is marked by a physical scream of sorts as they go through a stage of powerful outflows of material. Eventually they calm down and settle in for a life determined by what they weighed at birth (the amount of mass they have). Lesson Seven examines the theoretical ideas of how stars are born and the observational evidence to support these theories. Recent results from the Hubble Space Telescope have given us tantalizing evidence that newly formed stars have material around them that may contain planetary systems. These images plus the recent discovery of planets around dozens of nearby, solar-like stars hint that the formation of planets may be a standard by-product of star birth. The activity included with this lesson will give you an idea of what astronomers must do to detect a planet orbiting another star.

Lesson Nine

Continuing with our study of the lives of stars, we follow them through their adolescence, old age, and their eventual death. Depending upon the mass they had at birth, some stars live an extremely long time while others go through life fast and furious. The stars that live a long time die without much fanfare compared to the stars that live only a relatively short period of time. The massive, short-lived stars go out in a blast of energy representing one of the most violent explosions in the Universe. Lesson Nine addresses the question, "How do we know all this?" by having the student "walk" through the process of constructing what is known as a "color-magnitude diagram" of two clusters of stars. These diagrams reveal not only the ages of the clusters (and thus the way stars of different masses age) but also the relative distances to the clusters.

Lesson Ten

Although most massive stars end their lives as neutron stars, a topic we started in the last lesson and finish here, a select few leave behind a remnant so massive that it collapses for eternity. Gravity is the force that stars fight their whole lives, and gravity is what wins in the end. To understand black holes (one of the reasons students take an astronomy course), we must find a way to describe gravity under such extreme conditions. This lesson introduces you to the theory of general relativity as proposed by Albert Einstein. Don't panic! The textbook goes through the theory in a logical, comprehensible way. You will marvel at yourself as you find you actually understand this whole new way of thinking about gravity. This lesson includes an activity where you probe one of the first pulsars detected—the one in the Crab Nebula. Near the center of this nebula lies the remnant of a star that exploded in the year 1054. Each time the object rotates, which happens roughly 1000 times a second, bursts of energy are directed towards the Earth.

Lesson Eleven

We end this course with the study of our galaxy, the Milky Way. Up to this point, we have concentrated on gaining the fundamental knowledge needed to understand the stars in the Galaxy and some of the ways they may end their lives. Stars give material back to the interstellar medium whence they came. The "stuff between the stars" was mentioned during the birth of stars, this lesson pursues the topic in greater depth. How do we know the shape and size of the Milky Way? What lies at the very center of our galactic home? The lab exercise assigned to this lesson introduces you to a special type of variable star, called an RR Lyrae variable, that has been instrumental in our measurements of distances within the Galaxy. At the turn of the 20th century, around 1920, astronomers believed that the solar system was close to the center of the Milky Way, and that our galaxy was the entire universe! By using the special characteristics of the RR Lyrae stars and observations of them in dozens of globular clusters, we learned that we were, in fact, about two-thirds of the way to the edge of our galaxy. The Earth was not the center of the solar system, and now the solar system was not the center of the Galaxy.

Lesson Twelve

Preparation for your final examination.

Submitting Assignments

Format

The instructions for each assignment give the format for submitting your work or provide a text file where you simply fill in your answers and include it in the body of an e-mail or as an attachment. For the labs, this may include filling in tables and showing some simple calculations along with short or essay-type answers. Your assignments will be graded and returned to you within a week. In the meantime, you should plan on starting the next lesson and assignment.

To submit assignments by e-mail, you should send a copy of the assignment to the instructor's e-mail address (see the "About Your Instructor" page). In the subject heading, be sure to include your Distance Learning student number, the course identification number, and the assignment number.

Each lesson includes some self-review that is for your personal use for preparing for the exams and is not submitted for grading.

Examinations

This course includes a midterm and a final examination. The midterm covers Lessons One through Five; the final exam, Lessons Seven through Eleven. The final exam is cumulative only in the sense that each lesson has built upon the information that came before. The criteria for grading the exams are included in the section "Course Grade," included as part of this introduction.

The exams are closed-book and mostly of multiple-choice format. You may bring a scientific calculator and a 5-by-7-inch notecard with as much information as you can fit on it. More details about the exams are supplied in Lessons Six and Twelve. You will be allowed two hours for each examination.

Course Grade (Grading System)

5 Lab Exercises	30 pts each	150 pts total
5 Activities	10 pts each	50 pts total
2 Exams	100 pts each	200 pts total
Total Number of Possible Points:		400 points

Your final grade will be determined by your overall percentage (interpolate between the values shown, if necessary):

95%+   4.0	70%     2.0
90%     3.5	65%     1.7
85%     3.0	60%     1.2
80%     2.5	55%     0.7
75%     2.3	< 55%     0.0

Study Tips

The principal author of your textbook, Andrew Fraknoi, is a nationally recognized leader in the field of astronomy education. The preface for the student contains a number of suggestions on how to succeed in your studies. Although these suggestions are geared towards the formal classroom, they can be adapted to an online, correspondence course. The bottom line, however, is that nothing beats sitting down and just doing it!

Learning the Vocabulary of Astronomy: You will confront what seems like a whole new language. Each lesson contains a list of key terms. Spend the extra time it takes to become familiar with these words and phrases and how they are used in astronomy. Your understanding of the material depends on it.

Asking Questions: You may feel isolated from the rest of the students taking this course and from your instructor. This isolation can be minimized by asking questions, as many as you need to ask. A correspondence course has a great advantage over the classroom: you do not have to worry about "asking a stupid question." For your instructor, no question is a stupid question, period. There will be opportunities to post questions where others may read them and respond; we guarantee that other students will be thankful someone was able to put into words what they were having trouble understanding.

Review: Each lesson has a review section, usually with answers provided. This review is a measure of whether or not you have adequately studied the textbook, online notes, and have thought about what was done in the labs and activities.

Web Connections

At the end of each lesson is a list of relevant and interesting links pertaining to the material covered. In addition, for most lessons, links are also given to educational sites that have related lesson plans and information for K-12 teachers.

There are so many interesting Internet Web sites covering astronomical topics that it is overwhelming. Almost all of them contain glorious, full-colored pictures and a wealth of information. The Internet has complete journal and magazine articles and detailed results of the research of the leading astronomers, not only in our country but also around the world. (There are also a lot of "garbage" sites; hopefully you will never come across these and waste your time.)

Textbooks usually emphasize images taken by large observatories and the Hubble Space Telescope, and the links provided are to Web sites owned by NASA and other government agencies and major universities. We've tried to complement this by providing links to pages maintained by organizations of amateur astronomers and astrophotographers.

Planning Your Schedule

The course is based upon the Astronomy 101 classes taught at the University of Washington. These courses are completed in one college quarter of 11 weeks (including finals week). If you apply yourself, as students who attend class (usually more than one class) must, you should be able to finish one assignment per week, including exams. Most lessons are designed to require an average of about fifteen hours, the equivalent of five hours of class time and ten hours of study time per lesson for in-class work.

It is extremely important that you set your goals and deadlines and then stick to them. Please turn in your assignments on a timely basis; do not wait until you have finished a number of them and submit them all at once. The best way to learn from these assignments is to have feedback shortly after you have completed them. This will not be possible if weeks have gone by since you last looked at them. Learning is next to impossible, and your grade will suffer accordingly, if you wait until near the end of the six-month deadline and then try to complete the course in a month or less.

Using E-Mail

The advantages of using electronic mail in this course are as follows:

• You can get personal answers to your questions more quickly than by regular mail.
• Electronic mail will increase the timeliness of my response to your assignments.
• Establishing an Electronic Mail Account. If you do not have an electronic mail account, you can establish a UW Uniform Access account by doing one of the following:
  • If you are a matriculated UW student, follow the instructions in the "Getting Started" section of the Guide to Information Technologies and Resources via the University of Washington.
  • If you are not a matriculated UW student, or if you need help setting up your account, call Distance Learning at (206) 543-2350 or (800) 543-2320 (voice), or (206) 543-0898 (TDD).

General Questions

Once you have an e-mail account, you can address questions about this course to your instructor.

About the Course Developer

Dr. Ana M. Larson's research has covered the radial velocity changes seen in stars with the hope of detecting extra-solar planets as well as modeling their atmospheres.

Dr. Larson writes: "My cohorts and I detected suspicious variations in the star known as Pollux or beta Gemini that closely mimic what we would see should it have an orbiting planet. Unfortunately, this star is also what is known as a giant, and giant stars usually have too much going on in their atmospheres to unravel the possibility of a planet. By "modeling their atmospheres," I mean that we are able to set up a computer program that calculates the abundances of elements and the pressure, temperature, and density of a star at various depths in its atmosphere. We then compare the theoretical spectrum to the spectrum we observe and see how close our model comes to the real thing.

"As a returning student with two preschool children, my interest in astronomy was initially spawned by correspondence courses in Introductory Astronomy, The Planets, and Life in the Universe. My first degree from the University of Washington was in Business Education. Once my children reached elementary school age, I returned to get bachelor's degrees in physics and astronomy. My doctoral work was done subsequently at the University of Victoria, Victoria, British Columbia, where I spent many, many nights at the Dominion Astrophysical Observatory observing nearby stars."

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