Astronomy 1: Introductory Astronomy

Archive of Assignments

Week 14

updated May 1

Look over the slides from Thursday's class and get in touch if you have any questions.

updated Apr. 29

For our final class, on Thursday, please read section 3 of Ch. 20. We'll start the class by looking at evidence for dark matter in galaxies (and remind ourselves about the results of weighing galaxy clusters). Then we'll talk more specifically about measuring distances to galaxies, and see how distances are correlated with galaxy redshifts, indicating that the universe is expanding. We'll use this observation to estimate the age of the universe.

Before Thursday's class, please also look over the slides from Tuesday's class. Please pay special attention to the last five or six slides, which we'll begin Thursday's class with (I didn't show them today due to my computer freezing up toward the end of class).

updated Apr. 27

Homework #11 is due on Friday, May 2, at 5pm. Update: the solutions are available.

See the reading assignment posted on Apr. 24, below.

updated Apr. 24

In preparation for Tuesday's class, look over the slides from today's (Thursday's) class and (re-)read the first two sections of Ch. 20. If you've got time, read the rest of Ch. 20, too.

Week 13

updated Apr. 24

In preparation for Tuesday's class, look over the slides from today's (Thursday's) class and (re-)read the first two sections of Ch. 20. If you've got time, read the rest of Ch. 20, too.

updated Apr. 22

No new reading for Thursday's class, but make sure you've read up through section 2 of Ch. 20. We'll finish up our discussion of spiral structure in the Milky Way and then use Kepler's third law to weigh the massive black hole at the Milky Way's center and then move on to other galaxies: galaxy types and distances to galaxies. Also, review the slides from Tuesday's class in preparation for Thursday's class.

updated Apr. 20

Homework #10 is available, and is due on Friday, April 25, at 5pm. Update: you can look over the solutions.

Week 12

updated Apr. 17

Before Tuesday's class, review the slides from the most recent class. And also read all of Ch. 19 carefully. We'll be focusing on: the Star-Gas-Star cycle, the contrasting properties of the disk and halo, the nature of interstellar gas and dust, and the massive black hole at the center of the Milky Way galaxy.

updated Apr. 16

Start reading Ch. 19, on the Milky Way. Don't worry if you don't have it all read by class time on Thursday. We'll start discussing the material then, but will finish up next Tuesday.

The Wednesday and Thursday night sections will be trying to make up the second observing lab. Read that manual ahead of time, as there are quite a few different observations you'll be making, and you'll be comparing some of them to observations you made in the first observing lab.

Week 11

updated Apr. 12

The Monday and Tuesday lab sections will be doing the Expansion of the Universe lab. Please look over the manual carefully, especially as this is material we have not yet covered in class. For the Wednesday and Thursday night sections, you'll be trying to make up the second observing lab. Read that manual ahead of time, as there are quite a few different observations you'll be making, and you'll be comparing some of them to observations you made in the first observing lab.

updated Apr. 11

The exam will be on all the material since the first midterm: the Solar System, Exoplanets, Telescopes, and the historical development of astronomy. Here is the equation sheet you'll be given in the exam. Updated on Apr. 13.

Look at this gif of Venus cycling through its phases. Can you identify the phases that show that the Ptolemaic system is wrong? And can you explain why Venus looks bigger at certain phases?

updated Apr. 10

Review the slides from Tuesday's class (plus the separate set, showing the retrograde motion animations) and the slides from Thursday's class.

updated Apr. 4

When you have a chance, take a look at these articles announcing the discovery of a liquid water ocean on one of Saturn's moons and evidence for organic molecules (careful, not biological molecules) in it: New York Times and a short and slightly more technical (but not overly so) article from Nature.

updated Apr. 3

Homework #9 is available, and is due on Wednesday at 5pm. Update: The solutions are now available.

Read Ch. 3 for this coming week. Focus on sections 2 and 3 of the chapter. Update: And also read sec. 4 of Ch. 2

Review the slides from Thursday's class. I'll be glad to answer any questions about telescopes in class this coming Tuesday.

Week 10

updated Apr. 4

updated Apr. 3

Homework #9 is available, and is due on Wednesday at 5pm.

Read Ch. 3 for this coming week. Focus on sections 2 and 3 of the chapter. Update: And also read sec. 4 of Ch. 2

Review the slides from Thursday's class. I'll be glad to answer any questions about telescopes in class this coming Tuesday.

updated Apr. 1

For Thursday's class, please review the telescope-related slides from class 19 and the reading from Ch. 6 on telescopes and detectors. If you have time, you can get started on Ch. 3, which will be the focus for next week (though we'll start the topic — the historical development of modern astronomy — on Thursday).

Look over the slides from Tuesday's class, they are quite a few of them and they provide a good summary of exoplanets, as well as having some introductory information about telescopes.

updated Mar. 30

Some, but not all, of these links were already posted late last week.

Check out the slides from Thursday's class. We'll wrap up exoplanets on Tuesday. On Tuesday we'll also discuss the basics of how telescopes work, and what their key properties are. Telescopes (and detectors) are covered in Ch. 6. For Tuesday's class, please read the first five pages of the chapter (p. 172 to the very top of p. 177), and skim the rest of the chapter. You should also read the summary information at the end of the chapter (p. 191 and the very top of p. 192).

You can create your own plots that display the properties of known exoplanets at the exoplanets.org website. We will be making some of these plots in Tuesday's class.

Please read the lab manual for Observing the Sky pt. 2 ahead of this week's lab meeting. Note that there's a little bit of textbook reading to do in preparation and you should also look over your results from the first observing lab for the position of Betelgeuse and Polaris, especially, as well as your sketches of the sky. (Part of the goal of this next lab is to see how these things have changed since February.) Note: If the weather's bad, we'll do our last scheduled lab, on the expansion of the Universe, instead. The manual for the Expansion of the Universe lab is rather long, so budget some time to read it before coming to lab.

Week 9

updated Mar. 28

Our fifth lab will be held next week. All four sections will attempt to do the second observing lab. Please read the lab manual ahead of time. Note that there's a little bit of textbook reading to do in preparation and you should also look over your results from the first observing lab for the position of Betelgeuse and Polaris, especially, as well as your sketches of the sky. (Part of the goal of this next lab is to see how these things have changed since February.) Note: If the weather's bad, we'll do our last scheduled lab, on the expansion of the Universe, instead. That manual will be posted here by Monday morning.

updated Mar. 27

Check out the slides from Thursday's class. We'll wrap up exoplanets on Tuesday. Stay tuned for an assignment for next week.

You can create your own plots that display the properties of known exoplanets at the exoplanets.org website.

Look over the slides from Tuesday's class. And as you think about indirect methods of exoplanet detection, based on measurements of the host star's light, you can make your own orbiting planets with the orbit simulator.

updated Mar. 23

The next homework assignment (HW #8) is available. It's due on Friday, by 5pm. Update: The solutions are now available.

updated Mar. 21

Start reading Ch. 13, on exoplanets, for Tuesday.

Look over the slides from Thursday's class - on the formation of Solar System. And watch this simulation of the formation of the moon. And the simulation of the gas giant planet forming, with the stream of gas "feeding" it. Note that the view is looking down on the protoplanetary disk, from a rotating reference from so our view moves along with the forming planet, which makes it appear not to move.

Week 8

updated Mar. 20

This is optional, but you might want to play with the My Solar System orbit simulator. More information. We saw in class how two objects orbiting near each other in relatively stable-looking orbits can fling each other around suddenly. We should expect that early in the history of the Solar System asteroids, comets, and large planetessimals were bombarding the inner solar system.

updated Mar. 19

There is no new reading for Thursday's class, but you certainly should review your notes from Tuesday and look back over the reading. Here I provide a few specific item/concepts/figures/images you should especially review:

Check out the two minute drone-shot video of an erupting volcano I showed at the start of class. It's good to remember that planets are dynamic and often quite hot on the inside (or at least different on the inside than the outside)

Saturn's ring system is a good example of an orbiting disk (often referred to as a "rotating disk") of material which looks like a single coherent object but is really but up of numerous independent particles/objects orbiting in the gravitational field of a central, massive object. One important difference, though, is that Saturn's ring system does not have any gas in it (it is made of mostly icy particles), whereas the proto-planetary disk orbiting around the young Sun did have a lot of gas in it, as well as rocky, metallic, and icy particles or some subset of these, depending on the local temperature in the disk. Check out these images (click on each for more information).

Although you can't see any individual ring particles in these images, you can see some small moons orbiting within the rings.

For fun, here are some images of what the view on Earth might look like if we had a ring system on our planet.

To form a orbiting disk, we need to think about gravity and also about rotation and angular momentum. Check out the trailer for Gravity. Watch especially the bit from about 15 seconds to 45 seconds. Gravity isn't the issue, momentum and angular momentum are! Note how once something starts spinning, it really wants to keep spinning.

Look over this set of slides I put together a few years ago that goes over the explanation (that I gave at the board on Tuesday) for why a cloud collapsing under its own gravity and also rotating will naturally form an thin, rotating disk. Note that the capital "L" with the funny symbol above it represents angular momentum.

Recall that I showed a few figures and tables from the textbook that are especially important. You should review them: Tab. 7.2, Tab. 8.1, and Fig. 8.5.

Finally, you should have a solid understanding of how the Nebular Theory explains the key properties of the two types of planet in the solar system. Here is an assignment for you - though I won't collect it; you should do this either on your own or by talking it over with a classmate - write a short (about three sentence) paragraph, explaining why the Jovian planets are farther from the Sun, have a different composition, and are bigger than the Terrestrial planets. You can start by assuming we've got an orbiting, flattened protoplanetary disk. Key concepts/phrases that should make their way into your paragraph include: "accretion", "solids", "condensation temperature", "snow line", "gas", and "gravity". If you have trouble doing this, you should come to my office hours and we'll talk it over.

updated Mar. 14

Continuing on our study of the Solar System, we'll be discussing the formation of the Solar System, starting on Tuesday. The "Nebular hypothesis" has a lot of explanatory power and a lot of evidence in its favor. As you read Ch. 8 (I've left the assignment from last week posted below; looking over the slides from the last class before break would also be useful preparation for this week's material), please focus on both understanding the mechanism and on the evidence for it.

The next homework assignment (HW #7) is available. It's due on Friday, by 5pm. Getting started on it early could help you get more out of our class meetings this week. We will be having an SA session as usual on Wednesday night. Update: You should look over the solutions to HW #7.

Read the manual for the Seasons lab in preparation for this week's lab meeting.

updated Mar. 6

Look over the large number of slides from Thursday's class - on the Solar System.

For the first class after break, we'll be discussing the formation of the Solar System. We'll apply our knowledge of the trends we talked about in class today. To prepare for our next class, please read Ch. 8.

Week 7

updated Mar. 6

Look over the large number of slides from Thursday's class - on the Solar System.

updated Mar. 4

As you read Ch. 7 to prepare for Thursday's class, please focus on the introduction — the first page of the chapter, and the two page somewhat-to-scale diagram of the Solar system. The information about each object in the rest of 7.1 is useful, but what's really important are the trends, which are summarized in sec. 2, and which you should read carefully. The information in sec. 3, about spacecraft missions to the planets, is certainly interesting, but less central. And you should carefully read the short chapter summary at the end, which is always a good idea.

I'd also highly recommend that you spend a few minutes on the Astronomy Picture of the Day website, and search for images of a few of your favorite objects, and read about those images. Here's one awesome one: ultraviolet view of the Sun.

updated Mar. 3

Here is a document, which I'll keep updating as questions come in, with a list of changes to the equation sheet and student questions and my answers.

updated Mar. 1

Your focus this week should be on preparation for the midterm. The test will be closed-book, but you will be given this sheet of constants, conversion factors, and equations (updated at 6:15 pm on Mar. 1, correcting a unit error; and again at 10:30 pm on Mar. 2 to correct a mistake in the parsec to light year conversion). Take a look at it now. Let me know if you think anything important is missing. Note that the equations are almost all given without explanation or units. You will have to know how to use them and what they mean, but you won't have to memorize them. Here is the review sheet, covering the first six weeks of the semester, that I made available to you last week. It hasn't changed since Feb. 25; I'm just putting it here for your convenience. Similarly, here is the sheet of review questions I gave you prior to last Tuesday's class.

Bring a calculator to the exam (you will not be allowed to use your phone), as well as something to write with. You will be given a copy of the equation sheet, linked above, but otherwise won't have access to any other information. Please look over the review sheets and the equation sheet - if you have any questions, look in your notes, the textbook, and the archive of old assignments on the class website, but if you remain uncertain or confused, email me and I'll answer your questions.

On Thursday this week, we'll start learning about the Solar System. Please read all of Ch. 7 in preparation for Thursday's class. There are no lab meetings this week, nor is there any homework.

Week 6

updated Feb. 27

Look over the slides from Thursday's class (these should be helpful for your midterm preparation; not that I've added a few slides at the end elaborating on star cluster ages (something I didn't get to in class) and also a few extra slides about binary stars and the Doppler shift — take a look at those slides and see if you can answer the associated questions).

updated Feb. 25

Look over the slides from Tuesday's class (I've annotated a few of them).

You should read over these brief reviews of the main points of each class so far this semester (updated Feb 25). If you understand each of the concepts discussed in this document, you will be well-prepared for the midterm.

updated Feb. 24

For Thursday, read Ch. 17 [part 1 and part 2], which is on stellar evolution. Please focus on the basic concept: stars evolve as their energy sources change (because, e.g., they run out of hydrogen in their cores), and that mass and gravity require pressure to balance them, that fusion energy provides that pressure, and that the star's luminosity has to be equal to the fusion energy production rate in its interior. There are quite a few less-important details in the chapter too. On Thursday, we'll go over the material and I'll make sure to clearly emphasize what's important and what's just a detail — but you will only benefit from this if you've done the reading prior to coming to class.

Our sixth homework assignment is now available. It is due by 5 pm on Friday. There's an SA session on Wednesday night from 7 to 9, and David has office hours on both Thursday and Friday. Update: you can look over my solutions to HW#6.

updated Feb. 23

Read over the lab manual for the Observing the Sky pt. 1 lab, which we'll try to do this week (it is the lab that was scheduled for our last lab meeting, but all four sections did the Moons of Jupiter lab instead). New (2/24): If your lab section can't do the observing lab because of bad weather, you'll be doing the next lab on the schedule, which is about the cause of the seasons. Read that manual in preparation for the Seasons lab. Note that there's a little bit of background reading you must do before coming to lab, though there are no pre-lab questions to hand in.

For Tuesday's class, we'll be wrapping up the H-R Diagram, star clusters, coming back to binary star orbits, and setting the stage for Thursday's discussion of stellar evolution. You should make sure you've done all the assigned reading from last week and spend some time looking over the links associated with last week's assignment.

Update: You should also review the slides from our last class. You should read over this sheet of questions/concepts and answer each one. I won't collect your answers, but you should bring them to class on Tuesday, as we'll be discussing them there. You can think of this assignment as the beginning of your review for the midterm, as well as preparation for class on Tuesday.

I will also post some information along the lines of a comprehensive review of the first five weeks of material, to help you prepare for the midterm on March 4.

And a new homework assignment will be posted here, too, but maybe not until Monday.

Week 5

updated Feb. 19

I wrote up one page summaries of the key concepts from last Thursday's (2/13) class and this Tuesday's (2/18) class (classes 8 and 9). Have a look at the them [class 8 and class 9]. These are not meant to be comprehensive notes of everything covered in each class, just the key points, diagrams, and equations. When looking at the sketch of the stratification of the Earth's atmosphere in the class 9 summary, compare it to Fig. 14.1.

Also take a look at these useful images and brief explanations that should help with some of the important concepts we've been discussing recently, and will discuss tomorrow: (1) Remember this bit about how to think of frequency? Here's something more visual and comprehensive. As you look at this, you can think about the relationship between frequency (how many per second?) and period (how long — in seconds, usually — is one cycle — wave, orbit, whatever?). (2) xkcd has a nice chart of the Universe and its scale (think Powers of Ten; and that image of the Eiffel Tower is a great way to think about what logarithmic axes do to a plot). (3) Take a look at, and refer back to, this useful periodic table - H and He are simple and make up 98 percent of the regular matter in the Universe; nearly all the other elements are made inside stars as they desperately try to hold themselves up against the force of their own gravity. (4) The energy level diagram of hydrogen (H) is a useful reference, and the few electron Volt energy scale (about 10^-18 Joules) represents the maximum amount of energy available per atom from chemical processes. Nuclear reactions are a million times more energetic (converting 4 H to 1 He extracts 10^-12 Joules of nuclear binding (potential) energy — that's several MeV (mega-electron Volts)). (5) Play around with this binary star simulation (Java required; sorry). You can play God! Make your own binary star systems and watch them orbit and also see the observable properties — Here's one that simulates eclipsing binaries, and here's another one. And the Binary Star Wikipedia page isn't too bad.

There will be no pre-class question for tomorrow's (Thursday's) class. I have posted my solution to Tuesday's pre-class question below, in the Feb. 17 section.

updated Feb. 17

For Tuesday's class, answer this question prior to coming to class. It will get you ready for our discussion of pressure and gravitational equilibrium, which is what we'll start in on on Tuesday morning in class. Update (2/19): Check my solutions to this problem.

updated Feb. 16

Our fifth homework assignment is now available. It is due by 5 pm on Friday. There's an SA session on Wednesday night from 7 to 9, and David has office hours on both Thursday and Friday. Update: take a look at my solutions.

updated Feb. 15

For this coming week (2/18, 2/20), read the first two sections of Ch. 14, focusing on (1) pressure gravity balance and (2) nuclear fusion as the energy source for stars (as in the Sun). And then read Ch. 15, sections 1 and 2 (we'll read section 3 for Thursday, so you can read ahead if you want). For Tuesday's class, pay special attention here to (3) parallax (which is an excellent way to measure distances) and (4) the different types of binary star systems and what we can learn from each (note the images of the Sirius system in Fig. 15.6). For Thursday's class, we'll discuss (1) the stellar spectral type sequence (Tab. 15.1 and surrounding text), (2) the Hertzsprung-Russell diagram and the main sequence, (3) stars that aren't on the main sequence, and (4) star clusters (that material is in sec. 3 of Ch. 15, so by Wednesday night you should have read (carefully!) all of Ch. 15 as well as the first two sections of Ch. 14). Pace yourself! And absolutely feel free to email me with questions anytime.

Week 4

updated Feb. 13

For next week, read Ch. 15, sections 1 and 2 (we'll read section 3 for Thursday, so you can read ahead if you want). And read the first two sections of Ch. 14 as well. Topics to pay special attention to include (for Ch. 15): the inverse square law (you already know this; good to review), parallax (excellent way to measure distances), stellar spectral type sequence (Tab. 15.1 and surrounding text), the different types of binary star systems and what we can learn from each (note the images of the Sirius system in Fig. 15.6), the Hertzsprung-Russell diagram and the main sequence. And for Ch. 14, pay special attention to: gravitational equilibrium and also nuclear fusion.

updated Feb. 12

Take a look at the slides from Tuesday's class.

updated Feb. 11

Our fourth homework assignment is now available. It is due by 5 pm on Friday. There's an SA session on Wednesday night from 7 to 9, and David has office hours on both Thursday and Friday. Update (2/23): Take a look at my solutions to HW#4.

Week 3

updated Feb. 7

Read all of chapter 4 of the textbook for this week. Your focus should be on orbits; many of the other topics are related.

Read the lab manual for the observing lab before coming and bring a copy of it with you. This one's kind of long - and there are a few pages of background reading from the textbook you have to do in preparation for the lab.

updated Feb. 6

You can take a look at the stellar spectra, primarily from binary and triple star systems, that I showed in class [pdf or PowerPoint] - note that the PowerPoint will display the Doppler shift animation, while the pdf won't.

updated Feb. 5

To prepare for Thursday's class, go back over the slides I showed in class on Tuesday. I've added a few explanatory notes to several of the slides. You might also benefit from rereading the last few pages of Ch. 5.

And also, check out a couple of demonstrations of the Doppler effect:

Here's a few-second video clip of an ambulance driving by. It's a good for giving you a visceral sense of the reality of the Doppler shift (short wavelength and high pitch when it's coming toward you and long wavelength, low pitch when it's going away from you). The good part starts around 8 second in.

This is a nice little interactive demonstration of the Doppler shift, showing both the emitting wave and the observed wave. We'll use it in class tomorrow - it would be great to spend a few minutes playing with it tonight or tomorrow morning, before coming to class.

And this is a pretty good tutorial on the Doppler shift. It's three minutes long, and the most important part is around 1:40 to 2:10, I think.

updated Feb. 3

Forgot to post this after last Thursday's class, but here are the small number of slides I showed in the last class. Take a look at them. We'll see more images of spectra - interesting ones, of actual stars, in class on Tuesday.

If a scan of the two pages of reading about gravity would be useful to you, here it is. Just focus on the right column of the first page (the beginning of Sec. 4.4) and the left column of the second page.

The first three questions of our third homework assignment are available. I'll add a few more questions by Tuesday and the whole assignment will be due at the end of the afternoon on Friday. Update: No new questions have been added. Here is the final version of the homework (same as the preliminary version, but with a few clarifications to question 2). And here are some tips/hints for tackling problem number 3. And here is a thought about rates and frequencies. Update: You should look over the solutions to these homework problems.

updated Feb. 1

On Tuesday in class, we'll finish up our discussion of the physics of light. We'll focus on the following topics, all of which are in the Ch. 5 reading assigned last week - so you may want to review select parts of that reading, plus your class notes - Kirchoff's laws and the three kinds of spectra (Fig. 5.4), how we can understand/interpret absorption line spectra of stars (no particular reading as of now, but soon we'll read more about this in Ch. 15 - if you want to read ahead - on pp. 498-500 and Table 15.1), more on the connection between spectra and atomic structure (e.g. Fig. 5.15), and applications of thermal radiation (so, p. 161), and the Doppler shift (which we did not discuss on Thursday and is covered in sec. 5.5). We'll also spend a few minutes at the end of class starting to talk about gravity and orbits. It's by understanding orbits that we can actually weigh - determine the masses of - stars. To prepare for this you can skim Ch. 4, from the beginning but you might find much of the material there to be a review of things you already know (though certainly that may not be true for everyone). For Tuesday's class, the only part of Ch. 4 it is vital to read is the first little bit of Sec. 4.4: The Universal Law of Gravitation (pp. 127-128). I will scan and post those pages by the end of the weekend. And I will add a few additional things for you to look over to prepare for Tuesday's class (like a couple of on-line demos of the Doppler shift), but no major additional reading before Tuesday.

Week 2

updated Jan. 28

The second homework assignment is available. It's relatively short — just three questions, and it's due at the end of the afternoon on Friday. New: (Feb. 7) You can check your graded homework with my solutions to homework 2.

Also, you should take a look at my solutions to the first homework. Take a few minutes to look it over, compare my solutions to yours and note my explanations for each answer I provide. They're a little longer and more involved than is strictly required, but you can use them as a model for your own solutions for future homework assignments.

There is no new reading, aside from the remainder of Ch. 5, which was assigned already, yesterday (see below).

updated Jan. 27

The reading assignment (and topics) for Tuesday are posted below; and by the end of the week, we'll have finished all the material in Ch. 5. For those of you who don't yet have a textbook, here is the reading for the rest of the week: [Sec. 3, Sec. 4, and - for Thursday - Sec. 5]

updated Jan. 26

Read the lab manual for our first lab, which meets this week. Your lab experience will be so much better if you come to the lab prepared. Please read the manual ahead of time, and budget a few minutes to think about it after you've read it. Note that we do not give you explicit instructions for doing the lab, just a goal and a list of equipment, and you and your lab partner have to figure out how to achieve the goal. Note also that there are three pre-lab questions (on p. 2) that you'll hand in when you arrive at the lab. Please do them on a separate sheet of paper (not in your notebook) and make a copy for yourself. We'll discuss your answers at the beginning of the lab period. Finally, these brief, custom-written guides to error analysis and to the Kaleidagraph software, will be useful. Please read the error analysis document before coming to lab, and be ready to use the software guide (though careful study ahead of time isn't worthwhile).

A reading assignment and preparation tips for this week's classes will be posted here soon. Note that the prelab questions are good preparation for the material we'll be discussing on Tuesday, so getting a head start on those would be useful as class preparation, too. New: In Tuesday's class we'll go over the inverse square law of light, the relationship between wavelength and frequency for light, the particle vs. wave nature of light, how spectra are related to atomic structure, and a very important kind of light called thermal radiation. Some of these topics are covered in the textbook reading that was assigned last week. But others are in the next two sections of Ch. 5. So for Tuesday's class, please read sec. 5.3 and sec. 5.4 (pp. 149 - 161) and note the Mathematical Insight 5.2 on p. 161 - it's very important.

I'll also post some new homework here, too. New: A short homework assignment will be posted on Monday. It will be due on Friday and there will be an SA session on Wednesday night.

In the meantime, take a look at this awesome time lapse of the Moon (and more info) through one cycle of phases (and orbit around the Earth). You can see how its apparent angular size gets bigger and smaller as its distance from the Earth changes during its orbit. Also, you'll note that the same size of the Moon always faces the Earth, but it does wobble around a bit.

Week 1

updated Jan. 24

Look over the slides from Thursday's class.

updated Jan. 21

Your first homework assignment is available. It's short — just three questions, and it's due at the beginning of class on Thursday. Update: You can look over my solutions.

Look over the slides from Tuesday's class.

updated Jan. 20

I have two very short assignments for you to do, prior to coming to class on Tuesday:

Please watch the classic film, Powers of Ten, which will give you a sense of the scale of the Universe. The film is less than ten minutes long, so do take a look prior to coming to class. Powers of Ten was made in the early 1970s by husband-and-wife graphic and industrial designers, Charles and Ray Eames. Perhaps you know some of the chairs they designed, or their house. Check out this interactive tool for exploring the scale of the Universe in the style of Powers of Ten. And of course, there's a Simpsons parody (which, of course, is excellent).

And please read local Jersey-boy made good, Walt Whitman's peom, When I heard the Learn'd Astronomer.

For Thursday's class, we'll be reading the first two sections of Ch. 5 (up through p. 150) on the properties of light (here's a pdf of the reading) and also the first two pages of Ch. 15, on the inverse square law of light [pdf]. You can get started on that reading ahead of time, if you wish, but you don't have to. You do have to have it done prior to Thursday's class, though.

updated Jan. 19

Your first assignment, including some observing, was emailed out on Saturday. It is due on Monday by 3 PM, in the box outside my office (SC 125).

The assignment included some reading about angles (bottom of p. 29 through top of p. 31 [pdf]). We'll discuss these concepts, your angle measurements and sketches, and extend those concepts, in class on Tuesday. Come with questions!

To help out with your observing — identifying objects in the sky — I recommend you install the Stellarium software. It will be useful throughout the semester.

Return to the main class page.

This page is maintained by David Cohen
cohen -at- astro.swarthmore.edu

Last modified: May 7, 2014