Course Review: Astronomy: Exploring Time and Space

As I mentioned a few weeks ago, I recently took the Coursera class Astronomy: Exploring Time and Space, from the University of Arizona‘s Dr. Chris Impey. This review is written based on the course as it existed in March 2015.

This review serves three functions:

  • For prospective students, should I take this course?
  • For prospective employers and admissions offices, what does having completed this course say about a potential employee or student?
  • For course developers and educators, what can I learn from how this course is developed and delivered?

This review will contain two parts: an objective description of the course content, structure, and experience, and a subjective analysis of the course’s value to students, employers, and educators.

Course Description

Astronomy: Exploring Time and Space is a six-week class covering the basics of Astronomy, including the tools of astronomy,  the planets and the solar system, extraterrestrial life, and the origins of the universe. The full description is available here. The course is self-described with the following:

This course is designed for anyone who is interested in learning more about modern astronomy. We will help you get up to date on the most recent astronomical discoveries while also providing support at an introductory level for those who have no background in science.


Astronomy: Exploring Time and Space was a six-week course. Each week consists of a couple hours of pre-prepared video material, a couple quizzes over the material, and either a peer-reviewed writing assignment or an interactive activity.

Overall, the course can be completed in around thirty total hours including all activities. The lecture material averages two to three hours per week, while the quizzes, assignments, activities, and peer review total likely another hour.


Astronomy: Exploring Time and Space is broken into six units: “Our Place in the Universe”, “The Tools of Astronomy”, “Planets Near and Far”, “Star Birth and Death”, “Galaxies and the Big Bang”, “Life in the Universe”. Each unit is built around its overarching topic, and examines multiple elements of the topic. For example, the third unit — “Planets Near and Far” — covers the nearby planets, then the methods for examining planets further away, then interesting features of further-out planets.

Astronomy: Exploring Time and Space assumes nothing about the student’s knowledge; it is accessible to anyone. It goes so far as to start with the very basics of the scientific method: how science works, how observation, discovery, and reasoning lead to the scientific method, and how the scientific method is used in the context of astronomy. In line with this, Astronomy: Exploring Time and Space also keeps things high-level and accessible; little math is covered, and while the concepts covered are complex, the course focuses on giving beginner-level explanations. Rather than complex equations and slides of bullet points, Astronomy: Exploring Time and Space makes heavy use of animations, visualizations, and simulations. The course also injects a significant dose of humor and popular culture.


There are three types of assessments in Astronomy: Exploring Time and Space:

  • Thirteen short lecture quizzes (six questions each), made exclusively of multiple choice questions and permitting three retakes.
  • Three short writing assignments (500 words each) that are graded via peer grading.
  • Two activities using external sites, graded via some multiple choice questions.

Assignments are assigned to three peer graders for peer review, and each student grades three classmates’ assignments.


There are no necessary prerequisites for this class. I wouldn’t have any hesitation giving it to middle school students, and yet the course material should remain interesting to students with higher-level degrees but no experience in astronomy.

Identity Verification

For Verified Certificates ($50 at the time that I signed up), students complete the Coursera two-phase authentication: a typing sample is submitted and a picture is taken of the student immediately after completing the assessment. Assuming that these are adequate in ascertaining the student’s identity, they are nonetheless not difficult to circumvent. It would be trivial to collaborate with someone else on the assignments or even outright submit someone else’s work. This verification only assures that the student was present when the work was submitted.

If the student is not enrolled in a Verified Certificate, there is no identity verification at all.

Course Analysis

Astronomy: Exploring Time and Space uses a “talking head” approach throughout much of its presentation, but that approach is very often augmented with visuals, diagrams, animations, simulations, videos, and other forms of media. Additionally, despite the talking head approach, there are never any visuals resembling PowerPoint slides — the class is much more conversational. The ultimate effect of this is that the lectures are actually downright pleasant to watch. It feels like attending an interesting guest lecture or watching a well-prepared (albeit low-budget) documentary.

The assessments of Astronomy: Exploring Time and Space generally suffer from the structure I’ve seen commonly used in Coursera courses. The quizzes allow two immediate retakes, meaning that guess-and-check can earn a surprisingly good score on the quizzes. The writing assignments and the activities, however, do encourage significantly deeper understanding of the material for those topics covered by those activities — but as with most things, you get out of these what you put into them.

Aside from the lessons and the assessments, the course consists of the typical forums as well as a number of live sessions with Dr. Chris Impey. The forums, like many Coursera courses, are somewhat hit or miss: in this class a community didn’t seem to develop and most discussions did not go anywhere. The live sessions, however, were very interesting. Dr. Impey’s impromptu ability to answer some deep questions was particularly amazing. It would have been great to see an actual synchronous conversation on some of the questions that were brought up.

For Prospective Students

Astronomy: Exploring Time and Space is an excellent introduction to the high-level concepts of astronomy. It’s accessible to beginners in the field, so no prior knowledge is required. It nonetheless also goes deep enough into the topic to be fulfilling. I left the course wanting to know more, but I didn’t feel like the course itself should have gone in more depth on any particular topic. The title of the course is appropriate: it’s an exploration of time and space. It doesn’t cover every single thing, nor should it.

Take this course if:

  • You enjoyed Cosmos: A Spacetime Odyssey and want to learn more.
  • You have any interest in astronomy, but little prior experience.
  • You’re willing to do a little more than the traditional Coursera multiple choice quizzes (but not too much).
  • You have trouble learning from the traditional talking-head-and-slides presentation style.

Don’t take this course if:

  • You already have an intermediate background in astronomy (you likely know the course content already).
  • You’re looking for a class to replace a high school or college-level astronomy credit (the material and assessments aren’t quite deep enough to replace these classes).
  • You don’t want to write a couple essays.

For Prospective Employers and Admissions Offices

With regard to identity verification, the identity verification for the Verified Certificate is trivial to circumvent. Thus, a Verified Certificate in Astronomy: Exploring Time and Space should carry limited clout for that reason alone. The remaining analysis will infer that the student did complete the certificate themselves.

With regard to assessment, the rigor of the course is slightly higher than many other MOOCs, but not high. As referenced above, the multiple choice quizzes are easy to game without actually learning the material, meaning that the only reliable assessment is the written assignments. These are most certainly a matter of getting out of them what you put into them. In peer grading, I saw a wide variety of assignments, from comprehensive essays to three-sentence throwaway answers. While I, personally, have some reservations about the validity and reliability of peer grading, research has shown this approach to be effective.

With regard to content, Astronomy: Exploring Time and Space provides a strong overview of the basic principles of astronomy. Neither its coverage nor its assessments are sufficient to consider it as a potential replacement for high school or college credit, but it’s sufficient to demonstrate interest and qualification for taking a class that might otherwise appear to be out of the student’s ability level.

Personally, if I saw Astronomy: Exploring Time and Space on an applicant’s resume for admission to school or for a job, I would take it as a sign that the applicant has their own interests and is willing to put up more than minimal effort to pursue those interests. I wouldn’t derive any more conclusions based on this certificate, but that alone may be interesting to note.

For Course Developers and Educators

There are three main things in Astronomy: Exploring Time and Space that I’d like to see more courses do:

  • Diversify video content. Many courses are almost entirely comprised of a talking head alongside a set of PowerPoint slides. I understand the temptation of doing that; it’s easy, and Coursera courses aren’t money-makers, so the costs of production need to be kept low. However, I would not speculate that Astronomy: Exploring Time and Space cost more to produce than others; the time spent developing slides was simply instead spent gathering visuals and other resources. That’s a better use of the time in any course that can present content using something besides bulleted lists of vocabulary words and concepts. Astronomy: Exploring Time and Space is the first MOOC I’ve taken that I can imagine airing on television for a casual audience.
  • Diversify assessments. Many courses rely only on auto-graded multiple choice quizzes with several retakes. I find very little reliability in a person’s record from a course entirely made up of these assessments; anyone can complete them. The peer-graded assessments in Astronomy: Exploring Time and Space as well as the lecture activities (even though they are evaluated by similar quizzes) at least require student participation that cannot be totally faked. Better plagiarism detection measures could make this even more powerful.
  • Know your audience. The best part of Astronomy: Exploring Time and Space, to me, was in its cohesiveness and consistency. The entire course stays at the same level of presentation complexity and content depth. It knows its audience is novices to astronomy, and so it focuses on keeping things accessible, interesting, and enjoyable to watch. Not every class should focus on a beginner audience this way, but every class should know who its audience is and consistently cater specifically to that audience.

For more information, please see the course web site. If I’ve left out anything crucial to understanding this course, let me know below!

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