ASTB03 Great Moments in Astronomy
This page has all the essential information on the synchronous online course ASTB03, including syllabus, PDF lecture notes, home assignments, and other material. No other pages on other sites contain the current information (e.g., Quercus; outdated material published somewhere, or surviving online from past UTSC oferrings. Please check this site every week for updates.

Brief description of the course

We explore numerous key events in astronomy (and astrophysics) throughout the ages. While we pay much attention to the personas and stories involved in the discoveries, sometimes full of human emotions and ambitions, we also try to learn as much as we can about the Universe that created us, and witness the changes in ways the science (exemplified by astronomy) historically developed. Frankly, the latter aim is actually more important than the first.


Syllabus in TXT format contains the topics discussed on specific dates, and the dates of assignments and exams.


Max. 100% score breakdown:

4 Assignments = 7.5% ea., total 30%.
Midterm = 10%+10% (quiz and written problem).
Final exam = 25%+25% (quiz and written problems).
Activity 3% (based mainly on questions you ask in lectures and office hours; as you see these points are aditional to a total of 100% for other tasks; most students won't get them, it's a reward for exceptional involvement and activity.)

Grading of the final score is standard for UofT: minimum % for letter grades (for orientation only, since grades are reported as percentages): A+ 90%, A 85%, A- 80%, B+ 77%, B 73%, B- 70%, C+ 67%, C 63%, C- 60%, D+ 57%, D 53%, D- 50%, F 49% or less.

Teacher and TA contacts

Prof. Pawel Artymowicz
office: SW 506G (old science bldg., 5th floor) - almost never there during the pandemic;
emergency contact: 4163584275 (via text message to my cell phone)
email (the preferred way of contact): pawel /AT/
[There were occasional glitches in responding to my emails from this address due to the fact that, unfortunately, I have to redirect my outgoing mail through a gmail server. Students' browsers sometimes don't respect the 'reply to' line and incorrectly send their replies to a intermediary. Sorry for the trouble but please MAKE SURE that while responding, the mail is addressed to!]
TA: Emaad Paracha, email: emaad.paracha /AT/ First ask the TA, then the lecturer if TA doesn't have the answers you need.

Schedule of lectures, office hours

ASTB03H3 Lectures: Mondays 7-9 pm (zoom, schedule on Quercus)

Office hours: immediately following lectures, other times by email. Stay after lecture, ask any questions you didn't during the lecture (if the question may be of interest to others, I encourage you to ask it during the lecture!). By "any" I mean somehow connected to the subject of the course but not necessarily to the presentation given in the lecture.

Your attendance at the real-time Zoom lectures is very much recommended. The lectures do not follow a single textbook. Occasionally issues are outlined during lectures that aren't fully described in lecture notes (provided in pdf format below). Please take your own notes and ask for clarifications during and/or after lecture. Zoom recordings of meetings will be made available to you via Media Gallery in Quercus.

About the final exam

On Monday 13 Dec (the week of the final) there will be an extra Q&A session with the lecturer, starts 19:00 on zoom, ends when questions are answered or at least addressed.

Final exam is a 2.5 hr exam and follows the format of the midterm. It will take place on zoom like different from the regular lecture, the link will be repeated in an announcement in the week before exam, on 18 Dec 2021, 12:00-14:40.

Preparation for final quiz questions is in this file.

The solutions of the midterm may be useful to review: midterm with solutions   (text file).

Sample final exam (2015) is in this file (the exam format was different back then).

You write the written part during a zoom meeting by hand, or if you have a strong preference type it (but it's more cumbersome to do illustrating sketches that way). Your camera/mike needs to be ready & showing you (for proctoring), audio should be muted. You work on your quiz in text editor.
Submission method: taking a snapshot with the phone or computer camera, and submitting your work just like a home assignment, within 10 min after the end of exam. You will edit and submit the quiz file as well (in emergency, any format will do, although we ask you to submit quiz as text file to help with grading.) The Assignment tab in Quercus has been created for submission of files, and allows multiple submissions.

The final consists roughly of about 1/3 of material from before the midterm and 2/3 from the post-midterm part of the course. This way pre-midterm and post-midterm material gets equal weight. No calculators or electronic devices will be needed (your computer will provide a calculator if you need to do simple algebra). A good understanding of the astronomical issues and the knowledge of the Great Moments will suffice.

You decide which part, quiz or written, you do first. It makes sense to start with the quiz, since it usually goes faster and is worth the same as written part. The final quiz will have 60-65 questions. Written part will contain essay-type tasks (there were 2 in midterm, there will be 4 in the final). You may do drawings clarifying your answers. Prepare scratch paper for your written part ahead of the time, and write it by hand. If you have a strong preference, however, you may type and submit your written exam in a file; it may just be more difficult for you to include drawings.

Is the exam open-book or closed-book? Closed books, but during exam you will be able to use self-written note sheets (handwritten only, books/printouts & electronic communication not allowed). Up to 8 pages of handwritten notes are allowed at final exam. This way, you won't have to memorize so much. In fact, you likely won't spend any time searching for the handwritten information, you will simply remember the facts. The dates of events are something that you may want to look up from your notes.

What material/knowledge is required for the exam? In general - all the lectures (notes & recordings) up to the time of exam, your own notes from lectures.

Defered final exam on 18 April 2022 - 2.5hrs. The file

You need to login to a zoom meeting a few minutes before 10:00am to be proctored, and switch on the video, but mute the audio. Zoom invitation to meeting has been published in announcement sent to you via email by Quercus. The link is

In case of emergency (say, either you or I cannot login to zoom for some reason, you should go ahead, download, do and submit your exam. That's the priority. Submit the makeup exam to , and to Quercus assignments if you find the deferred exam tab.

If you don't have drawings in you written problem solutions and do everything in text editor (which you can do) then just submit that exam file. If you write the problems by hand, submmit a separate scanned/photo PDF file with, in addition to the edited exam text file with the quiz. But in emergency use any format you like.

Download this final exam by 10:01   (text file; access blocked before 10:00). Submit this file by 12:40.

At 10:01 you can start working on the exam. If you have questions during the exam, ask them in the zoom chat indicating ASTB03. If you can't connect to zoom, notify prof. by texting to 416-358-4275.

No books or electronic sources of any kind (no googling etc., no phones).

You can do the quiz and written parts in the order you like. The quiz is multiple-choice. Edit the text file and clearly indicate your choice by putting a mark # before letter a,b,c,d,e in front of your choice, e.g. [#b]. [We don't intend more than 1 correct statement, but should there be two acceptable answers, either one will get you a point, so just mark one answer that seems best.]

Writing of the makeup exam ends at 12:30. At that time you should put page numbers and student number on the handwritten pages. Within 10 minutes after that time, you should submit to Quercus Assignment and to
(i) the written part collected in one PDF document, just like you do your homework assignment;
(ii) edited quiz file with solutions (put the student number in that file too, pls).

In emergency you may deviate from recommended submission file formats (pdf for written part, edited text file for quiz). [We can read .docx .pdf, and some more specialized formats but would like to avoid sifting through scattered .jpg snapshots.]

Example questions for midterm illustrate the format of the final as well

Quiz (choose the best answer; only one should be chosen):
[1] Mars was a very important planet historically and it figured in many theories: (A) One scientific theory established its relationship with the god of war called Aries, because its color is red like blood; (B) On the sky Mars is never departing further than 45 degrees of angle from the sun. (C) Mars is brightest when it rises near the time of sunset, i.e. when it is in opposition to sun. The fact was used in Copernicus' books; (D) Mars is on an elliptic orbit, as Kepler has found. This is because when Mars is closest to Earth, its orbital speed is smallest; (E) Mars was known to have the so-called Great Red Spot by Ancient Chinese.
[2] Stars like our sun are (A) the basic constituents of a galaxy. There are up to about 1011 stars in a galaxy; (B) located on a "sphere of fixed stars" in the geocentric, Ptolemaic model, because they are fixed (always seen in the same direction); (C) producing energy by nuclear reactions in which radioactive nuclei split into smaller nuclei; (D) evolving to become brown dwarfs; (E) in reality planets: for example, Venus is known as the Evening or Morning Star.
[3] Aristarchus of Samos was a Greek astronomer who: (A) was a disciple of Copernicus; (B) proved that the Chinese "new star" was an expanding nebula; (C) predicted the famous solar eclipse in Memphis in 1322 B.C.; (D) first proposed that numbers and geometry describe the harmony of the world; (E) proposed a heliostatic system, in which the sun does not move, while the Earth moves in a circle around it.

Example written problem: Describe the life, work, and the greatest ideas of Copernicus, in relation to other theories and observations.
Sample midterm exam from 2018 (PDF)

Lecture notes and recordings

Recording can be viewed on Quercus, Media Gallery tab located in the left column of the Quercus course page. L12 hasn't been recorded, please use lecture notes instead. L13 was a midterm.

Lecture notes are provided here for your reference. They do not replace attending lectures. From experience, students who do not attend lectures get lower grades because they are not able to fully understand the contents of the lecture discussed using the provided concise slides. Lectures are more than the readings from slides. Coming to lectures, asking questions and taking notes is encouraged, appreciated, and on some occasion may be rewardable. The contents may evolve somewhat as the course preceeds, but a prelim. version of a coming lecture should be available agead of time.
If a full URL to a video mentioned in a lecture note is not given in the text of the lecture, there will be a quoted title (e.g., "Infinite Secrets") that you can find on Youtube. With most browsers and most of my coding of URLs, videos will start after clicking the link in the .pdf file.
Lectures 1 and 2 (PDF)
Lectures 3 and 4 (PDF)
Lectures 5 and 6 (PDF)
Lectures 7 and 8 (PDF)
Lectures 9 and 10 (PDF)
Lectures 11 and 12 (PDF)
Lectures 13 and 14 (PDF)
Lectures 15 and 16 (PDF)
Lectures 17 and 18 (PDF)
Lectures 19 and 20 (PDF)
Lectures 21 and 22 (PDF)
Lectures 23 and 24 (PDF)

recordings 15 and 16 (mp4)
recordings 17 and 18 (mp4)
recordings 19 and 20 (mp4)
recordings 21 and 22 (mp4)
recordings 23 and 24 (mp4)

Home assignments


You must respect the posted assignment submission deadline. Deadline time is the beginning of the lecture on a date posted in the syllabus. There are no personal waivers of the deadline (extensions) as this would violate the principle of equitability.
Home assignments will be published 7 days before the due date (so you can ask questions about them one week before due date).
Actually, for the benefit of some of you who need extended solving time, I'm going to publish the assignment 10 days before the deadline (if you are not among those students, you may want to read the text of assignment 7 days prior to due date; it's up to you).
You will submit the 4 home assignments to Quercus section "Assignments". That section allows you to upload files multiple times (if you have made corrections) before the submission deadline. Assignments should be either typeset in PDF form or handwritten and scanned by your camera/phone, then submitted as one file.

File name should indicate the number of the assignment and three last digits of your student number. For instance, assignment 1 of a student with student number 00123456 might be called A1-ASTB03-456.pdf. If you deviate from this scheme, don't worry - it'll just allow us never to mix up your work when we deal with it between me and your TA. Alternative file formats are .txt or .doc/.docx, they're allowed though we prefer .pdf

If the assignment asks for, say, 2 to 4 pages, this means the number of pages in electronic document (pdf) using a typical text file style i.e. single-spaced, reasonable (10pt to 12pt) font size. The count includes illustrations, if any.

Remember to always credit your sources at the end of the assignment in a sepatare bibliography section. Use more than one source, for instance one-half of the references from book(s) if appropriate, and half from the internet pages (state the URL address and name of the page in the literature listing). Do not include pictures in your work that are not in public domain (e.g., wikimedia pictures cited in wikipedia and NASA pictures are public domain, for instance) and for which you don't have copyright owner's permission. That's the general rule in the age of computers. But there is a loophole for us academics. Both in U.S. and Canada the law allows a limited use (citing a part of work) for the purpose of commenting on, criticizing, or parodying a copyrighted work. That's called Fair Use (US) or Fair Dealing (Canada). Use your rights! More info on how not to break copyright in this FAQ.

However, you may commit plagiarism even if you don't break copyright. For instance you cannot claim Fair Dealing if you just rip off a paragraph from author's text literally, without quoting the sourse of this copied parapragh. Even if in the next paragraph you do comment on or criticize that paragraph -- it's the issue of representing someone else's work as your own. So never cut and paste text literally from wikipedia or any other source, unless you list the source in bibliography (literature section). Also, how much do you think we will appreciate your homework if most of it consists of quotations (even if properly credited)? Do your thinking and writing on your own.

Number the references like so: "(...) Aristotle claimed that (...) [1], which was in contradiction to the later teachings of Newton [2]", then list the literature positions in bibliography:
[1] Aristotle, "Physics", 400 BC, as quoted by this or that book
[2] Newton, I., "Mathematical Principles of Natural Philosophy" 1798 (Basel, 5th ed.)
You may alternatively use this style: "Copernicus (1543) claimed that....", and order the references alphabetically. This style looks nicer in print but makes web page citations without obvious main authors more difficult, as you may not know how to call the document and thus where to place it in the list.

In general, use your head, your brain and your mind[1] - a bunch of main citations may be enough for a simple assignment on one topic only.
[1] quotation from the movie "School of Rock" 2003 (excerpts on Youtube service, URL =

Assignment 1. Ancient astronomy: Eratosthenes (due Mo 4 Oct)

Research in books and online the profile of a versatile ancient scholar Erathostenes. Summarize briefly all the interesting scientific things he has done in his life. Describe in more detail the following achievement: measurement of the size of Earth. How was it done and from what sources do we know it? What result was achieved, and with what precision, compared with the currently known value? (State if you are comparing to equatorial radius or an average radius of Earth assuming sphericity, or maybe you compare circumference not radius - state everything clearly.) Express the difference in percent, that is as a fraction of the modern value. Do you think the precision was a stroke of luck or genius?
Finally, consider the accuracy of his data: do you have any information or your own thoughts on which parts of the calculation may contribute the most to the estimation error; which assumptions made by Eratosthenes explicitly or implicitly may have been inaccurate?

Your document should be 1 to 4 pages of your original writing.

Assignment 2. How where cometary orbits deciphered (due Mo 25 Oct)

In lectures 7-10 we discuss the birth of celestial mechanics in 16th and 17th cent., mostly dealing with planetary orbits. We now know that most comets move along elliptic paths just like planets, only much much more eccentric (eccentricity e > 0.9). But in the 16th century nobody suspected that such a similarity of orbits exists or that the planetary and cometary orbits are governed by the same laws. Comets, following Aristotle's works, were in fact thought to be a meteorogical phenomenon, quite often considered an ominous sign (bad omen).

Find out and describe how the old paradigm broke down and the new emerged. Start with a very brief summary of ancient beliefs about comets. Two astronomers should get most of the credit for the change. The first was Newton, who corresponded with observer Flamsteed about the shape and dynamics of one comet (what was wrong with the Flamsteed's understanding of cometary paths? What did Isaac Newton propose instead as a trajectory?). The second is Halley, who first applied to many cometary paths the dynamics from Newton's Principia (that he edited and paid for publishing). This allowed Edmond Halley to calculate the perturbations by Jupiter and Saturn of the Great Comet of 1682, its modified orbital parameters, and thus the future time of return of this comet (now called Halley's comet or P/1) in the year 1758. (Give a brief summary of the scientific life of Halley. What is the story of that comet's calculation? Can you find when the historic identification of a past and a present apparition of Halley's comet was first communicated by him to the Royal Society? What were the implications for Halley and for physical sciences in general?)

You will find these resources useful (but do research a wider range of sources and decide which you find most informative):
(i) Rob Iliffe, "Newton. A very short introduction" (Oxford U. Press, 2007), avaliable electronically from UofT Library (or from the URL cited near the end of lecture notes L9..L10).
(ii) Halley and MacPike, "Correspondence & Papers of Edmond Halley" (Oxford, Clarendon Press, 1932), also avaliable from URL cited in lecture L9..L10.
(iii) web resources such as, and, and other.

Ideal length of your report is between 3 and 5 pages. (However, your work is not marked based on the number of pages, but on the contents.)

Assignment 3. Canals on Mars. Hubble Space Telescope (due Mo 15 Nov)

Lecture 14 and 15 cover the great moments in astronomical telescope design and construction. Augmenting these subjects, you are asked to study two moments of perhaps less prominent greatness, but very illustrative of the way scientific inquiry works. Describe each on 1.5 to 2 pages of text (typed, but if you prefer hand-written), and additional pages with pictures if any (they are not necessary but are always welcome in science like astronomy).

From chapter 6 of W. Wall's book "A history of Optical Telescopes" (Springer 2018, download from UofT library in PDF form) learn about the issue of the so-called canals on Mars, objects which were seen by many optical observers (who and using what instruments?) in the 19th century, but only some early 20th c. observers and nobody afterwards. Describe the story, relevant other progress of observational astronomy, and implications. What explanation of the phenomenon would you propose to accept; whatprovided the resolution of the issue?

From chapter 8 of Wall's boook learn about the issue of the flawed mirror on the Hubble Space Telescope. Describe the history of how it was discovered, what caused it, and when and how it was remedied.

In both tasks, please augment your presentation with facts provided by at least one online source of your choice (that is, find and cite some more information on the two issues from internet; If the web source is less informative than the book, explain why you think so.)

Assignment 4. Andromeda galaxy, E. Hubble et al. (due Mo 29 Nov)

In lecture 19 [cf. lecture notes] we discuss the discovery of a variable star that Edwin Hubble used to establish distance to the nebula in Andromeda constellation (M31). But we do not give many details, omitting even the precise value of the distance first measured by Hubble, and the fact that it was significantly off, compared to today's knowledge!
On about 4 to 5 pages of text (not counting any images you use for illustration), please describe the story of finding how far and what the nebula M31 is, mentioning contributions of Hubble but also other studies (whether right or wrong) before Hubble, by astronomers such as Curtis, Shapley, Slipher, and McPherson. When was a more correct distance found? How did Hubble originally estimate the number of stars and mass of M31, and how do these estimates compare with current knowledge? What significance did all these studies have for our concept of the universe beyond Milky Way? How does Andromeda fit the Hubble law? If you find something interesting about Andromeda galaxy, summarize it!

Please use the relevant chapters (especially 6 and 7) from the book "The Andromeda Galaxy and the rise of modern astronomy" by D. Schultz (Springer 2012), available from UofT library in electronic form, and at least one other source (can be online).


Plagiarism constitues a serious academic offense, which must be reported by the TA or lecturer to the administration. It automatically results in zero score for the whole assignment. Chair's office must be notified as per UofT academic rules - study the Code of Academic Behaviour of UTSC. (Not reporting suspected plagiarism to administration is an academic offense by the lecturer).

It is OK to discuss ideas on how to solve assignment tasks with other students or friends. It is not OK to copy parts of your assignment from someone elses work, from a web page etc. For example, if two students submit suspiciously closely worded and structured assignment solutions, we do investigate & if a determination of plagiarism is made (differences are superficial), then both students get zero mark for the assignment (one that allowed his/her work to be copied and the one who copied).

Copying whole sentences from internet resources is of course not allowed in assignments and is easily to detect thanks to the same Google that plagiarizer uses to find the aswer ibnstead of understanding the issue and writing about it in own words. If you want to cite someone else's work, use quotation marks for cited statements, then give a reference in your text to the item in the reference list (bibliography). [some of you only provided bibliography but no references in Assignm. set 1 - points will be subtracted for this!]

Of course you don't have to submit your own illustrations, you are free to give reference to figures (citing URL in bibliography), whenever copying the graphics into your work is allowed by the copyright laws. You can always give a link to other people's work published on internet, but not copy and paste their work! There are many exceptions to this restriction, for instance: the so called fair use clause in the U.S., public domain materials, media commons, and all pictures published by NASA (NASA & some other sources grant you the use of their pictures, but do not assume this automatically about other sources).

Results so far

Preliminary results will be available in this text file.

Readings for those interested (not obligatory)

Some basic history and fresh achievements are described in a textbook ASTRO listed as the first item below. Other books go deeper into the history and/or the discoveries. In the first lecture I will mention where you can find some of these books.

"ASTRO, Canadian edition" by D. BACKMAN, M. A. SEEDS, S. GHOSE and V. MILOSEVIC-ZDJELAR (Paperback, 2012 and 2013). ISBN 017654626X
"Plurality of Worlds. Origins of the Extraterrestrial Life Debate from Democritus to Kant." by Steven J. Dick (Cambridge University Press 1984).
"The forgotten revolution. How science was born in 300BC and why it had to be reborn." by Lucio Russo (Springer, 2004)
"Growth of Physical Science" by James Jeans (Cambridge U. Press 1947 and newer ed)
"Early Astronomy" by Hugh Thurston (Springer, 1994)
"On the Revolutions. Nicolaus Copernicus complete works" translated and commented by E. Rosen (Johns Hopkins Univ. Press, 1978)
"Uncentering the Earth. Copernicus and The Revolutions of the Heavenly Spheres" by William Vollmann (Atlas Books, 2006)
"Nicolaus Copernicus. Making the Earth a Planet" by O. Gingerich and J MacLachlan (Oxford U.Press, 2005)
"The book nobody read. Chasing the Revolutions of Nicolaus Copernicus" by Owen Gingerich (Arrow Books, 2004)
"Kepler" (Dover Books on Astronomy, 1993)
"Galileo. A life" by James Reston, Jr. (Harper Collins, 1994)
"Galileo" by John Heilbron (Oxford University Press, 2010)
"Dialogue Concerning the Two Chief World Systems" by Galileo Galilei, Albert Einstein (Foreword), John Heilbron (Introduction),
"Newton, A very short introduction", Rob Iliffe (Oxford 2007)
"On the shoulders of giants. The great works on physics and astronomy" with commentary by Steven hawking (Kopernik, Kepler, Galileo, Netwon, Einstein) (2002) (1260pp.)
"William and Caroline Herschel [electronic resource] : pioneers in late 18th-century astronomy" by Michael Hoskin (Springer, 2014)
"James Lick's monument : the saga of Captain Richard Floyd and the building of the Lick Observatory" by Helen Wright (Cambridge University Press, 1987)
"Edwin Hubble, the discoverer of the big bang universe" by Alexander S. Sharov and Igor D. Novikov (Cambridge University Press, 1993) Biography of Einstein (online)
"Truth and Beauty. Aesthetics and Motivations in Science" by S. Chandrasekhar (U. Chicago Press, 1987)
"The New Worlds. Extrasolar Planets" by F. Casoli and T. Encranaz (Springer, 2005)

Extra Material

[10 March 2015]
Researchers have found rare satellite dwarf galaxies, and candidate dwarf galaxies, in orbit around our Milky Way, the largest number of such satellites ever found in one go. read about it here

A new hi-res movie was created from tens of thousands of frames sent to earth from the space probe Cassini, which went into orbit around Saturn. The original frames are black-and-white, taken through filters. The color is restored using a computer on earth. NASA provides the data for such public projects freely on their site. One day the creators of this GIF may create a full-length IMAX movie. Notice that the spacecraft travels through the Saturn system, the planet does not tilt that way itself. Also notice the shadow of the planet on the rings and the thinness of the rings (the true ratio is 10 m : 50000000 m)

[05 Nov. 2014]
A new image from ALMA, the Atacama Large Millimeter/submillimeter Array, reveals extraordinarily fine detail that has never been seen before in the planet-forming disc around a young star, as announced by ALMA team.


HR 8799 is a planetary system. The central colorful blob covering the central star is an artifact of the method of imaging. Three planets have been imaged in 2010 (red dots with arrows indicating the direction and speed of relative motion). In fact, it was the first multi-planetary system ever imaged. Notice the scale in the lower right corner -- the planets are very far from their sun! This planetary system is larger than our (out to Pluto).

[16 Oct. '12] One of the nearest stars (see the table in Appendix to Backman textbook ASTRO) is alpha Centauri, or α Cen. It has just been announced that measurements of its radial velocity with unprecedented precision resulted in a discovery of an Earth-mass planet near to it. Remarkably, a lot of Sci-Fi stories have already been written about humans traveling to a planetary system around α Cen.

[14 Nov '12] A cosmic orphan (of which there are many) has been identified not too far from home: somewhat incorrectly the Telegraph calls it the 1st such discovery of a lonely planet in the Milky Way. CFBDSIR2149 is “homeless” and does not orbit any star, rather it wanders around in the Galaxy alone.

[19 Nov '12] Mail Online reports on an imaging discovery made with the Subaru telescope atop Mauna Kea volcano in Hawai. 13 times more massive (not larger!) than Jupiter, the extrasolar planet is on the border of a class of objects known as brown dwarfs (failed stars). It circles a star kappa Andromedae, which is 2.5 more massive than the sun. This blog is actually a better description of the planet.

Useful or just interesting links:

The local home page of Pawel Artymowicz
Last modified: Sept 2021