The Scale of the Universe

A set of computer simulations and curricular materials for teaching the history of galactic astronomy from Ancient Greece to the discovery of the cosmic microwave background.


Todd Timberlake
Associate Professor of Physics & Astronomy
Berry College
Mount Berry, GA

[Overview] [Syllabus] [Simulations] [Activities] [Textbook] [Credits] [Terms of Use] [Presentations]


This page contains curricular materials that I have developed for a course on the history of galactic astronomy. The course is intended to satisfy a science requirement for non-science majors. The course explores the historical development of ideas about our place among the stars from the Ancient Greeks to Big Bang cosmology. The main purpose of the course is to use galactic astronomy as an example for illustrating how scientific theories are developed and tested and how scientific knowledge changes over time.

I teach the course using interactive methods. Students work in small groups to complete worksheet-based activities. Most of the activities involve using computer simulations. Some of the activities make use of free planetarium software (Stellarium). The remaining activities use computer simulations that I have created using the Easy Java Simulations (EJS) package. These simulations are part of the Open-Source Physics (OSP) project and are available for free using the links below, along with all of the worksheets for the activities. Interested faculty may also be able to get a pre-publication version of a textbook for this course.

Syllabus and Projects

The syllabus for the course, which provides a list of topics as well as some details about how I run the course, is available below.

Computer Simulations

The computer simulations come in the form of Java executable files (JAR files). The programs should run on any computer with Java 1.5 (or newer) installed. All of the simulations were created using Easy Java Simulations (EJS) and are open-source, so you are free to alter and redistribute them (but please see the Terms of Use before doing so). You are free to use the simulations any way you wish, but I have developed a series of worksheet-based activities that use the simulations (as well as some other software and some physical equipment) to guide students through an exploration of this material. The worksheets are available below.

Warning: I am continuing to refine these simulations, as well as develop new ones. I will try to keep an up-to-date version of the simulations available here, but this could lead to some incompatibilities between the most recent version of the simulations and the activity/lab handouts posted below. If you want a version that should work well with the handouts, use the class-tested version. Otherwise, use the most recent version.

You can obtain the simulations using the links below.

Activities and Labs

The table below contains a list of topics that students explore in my Scale of the Universe course. For each topic I provide a link for downloading the corresponding worksheet (in pdf format), a list of the simulations related to that topic (with links to the class-tested version), and a list of any other materials needed to complete the activity. The worksheets designated with "(A)" are activities designed to be used in a single 75 minute class period. The worksheets designated with "(L)" are laboratory exercises designed to be used in a single 120 minute laboratory period. Ideally these materials should be used in the order in which they are listed, but there is some flexibility.

You are free to use (and even change) the worksheets, but please see the Terms of Use before doing so. If you wish to edit the worksheets, and you know how to use LaTeX (or are willing to learn), you can download a package containing all the .tex files and other necessary files (images, etc.) for all of the worksheet. To download this package click the link below:

If you would like to edit the worksheets but need them in a different format please email me ( and I may be able to accommodate you.

Please watch out for typos and other errors in these handouts. I cannot guarantee that they are without flaws - but the handouts posted here are all materials that I have used in my own class. Please work carefully through the exercises yourself before you give them to your students!

Topic Worksheet Simulations Other Materials
The Night Sky I (L) 121Activity1_NightSkyI.pdf Stellarium none
The Night Sky II (A) 121Activity2_NightSkyII.pdf Stellarium, CelestialGlobe none
Distance and Parallax (A) 121Activity3_DistanceParallax.pdf Eratosthenes, Parallax2D none
Cosmos: Greece to Copernicus (L) 121Activity4_Cosmos.pdf SuperiorPtolemaic none
Copernicus' Revolutions (A) 121Activity5_Copernicus.pdf DailyRotation, EarthOrbit, CopernicanSystem, VenusPhases none
Universe: Finite or Infinite (A) 121Activity6_FiniteOrInfinite.pdf AngularDiameter, Parallax2D none
Photometric Distances (L) 121Activity7_StellarDistances.pdf none none
Uniformity of the Stars (A) 121Activity8_Uniformity.pdf none none
Stellar Motions (A) 121Activity9_StellarMotions.pdf Parallax3D, StellarAberration2D, StellarAberration3D none
Dark Sky Riddle (L) 121Activity10_DarkNightSky.pdf none none
Models of the Universe (A) 121Activity11_MilkyWayModels.pdf StarSystemModels none
Motion of the Sun (A) 121Activity12_MotionOfSun.pdf ParallacticMotion none
The Construction of the Heavens (A) 121Activity13_ConstructionOfHeavens.pdf StarSystemModels, HerschelStarGages none
The Nebulae in the 19th Century (A) 121Activity14_Nebulae19C.pdf none none
Spectroscopy (A) 121Activity15_Spectroscopy.pdf none excitation lamps, spectrum tubes, incandescent lamp, spectrometer
Olber's Paradox (A) 121Activity16_OlbersParadox.pdf DarkSkyFiniteAge none
Photometry and Photography (L) 121Activity17_PhotoMetryGraphy.pdf none none
Radial Velocities and Binary Stars (A) 121Activity18_RadialVelocity.pdf RadialVelocityMeasurement none
Spectral Classification (L) 121Activity19_SpectralClasses.pdf Spectral Classification of Stars (CLEA program), StellarBlackbodySpectrum none
The H-R Diagram (A) 121Activity20_HRDiagram.pdf none none
Stellar Evolution (A) 121Activity21_InterpretingHR.pdf none none
Statistical Astronomy (L) 121Activity22_StatisticalAstronomy.pdf KapteynProperMotion none
Spirals: Dark Lanes and Novae (A) 121Activity23_SpiralsI.pdf none none
Spirals: Spectra and Motions (A) 121Activity24_SpiralsII.pdf SpiralNebulaRotation none
Cepheid Variables and Distance (L) 121Activity25_Cepheids.pdf none none
The Big Galaxy (A) 121Activity26_BigGalaxy.pdf ShapleyGlobularClusters none
The Great Debate (A) 121Activity27_GreatDebate.pdf none none
Cepheids in Spirals (A) 121Activity28_HubbleCepheids.pdf none none
Galactic Rotation (A) 121Activity29_GalacticRotation.pdf DifferentialGalacticRotation none
Absorption and Galactic Size (L) 121Activity30_Absorption.pdf ShapleyGlobularClusters none
Relativity (A) 121Activity31_Relativity.pdf none none
Relativistic Cosmology (A) 121Activity32_Cosmology.pdf EinsteinUniverse, DeSitterUniverse, LemaitreUniverse none
Expanding Universe (L) 121Activity33_ExpandingUniverse.pdf MilneUniverse balloon or punch ball, clamp, string, marker, ruler, stopwatch
Stellar Populations (A) 121Activity34_StellarEvolution.pdf none none
Radio Astronomy (A) 121Activity35_RadioAstronomy.pdf JanskyAntenna, GalacticHydrogenMapping none
Relics of the Big Bang (A) 121Activity36_BigBangRelics.pdf none none


I have written a textbook for the Scale of the Universe course. Although the textbook is not yet ready for publication, interested college faculty or high school teachers may be able to obtain a pre-publication version of the text for review and possible use in a college or high school astronomy course. Please contact Todd Timberlake ( if you are interested in receiving an electronic copy of the textbook for review.


Terms of Use

All of the materials on this page are available free of charge. Feel free to download the materials and explore them with no obligation whatsoever. However, if you use any of these materials in a class please contact me ( to let me know. I would like to receive feedback on the simulations and the worksheets (especially if you find an error!) and I would like to keep track of where they are being used. If you make any modifications of the simulations or worksheets I would like to know about it (if you made it better then I want to use your improved version!).

The Java programs linked above are Open Source Physics (OSP) programs that were created using Easy Java Simulations (EJS) and are freely distributable under the GNU GPL license. For more information about the Open Source Physics project visit

Creative Commons License
All of the curricular materials (including the narratives in the Launcher package) are copyrighted by Todd Timberlake and/or Paul Wallace and are licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License. You may modify and redistribute these materials for non-commercial use as long as you clearly cite the original author (Todd Timberlake for all simulations materials and the activity handouts, Paul Wallace and Todd Timberlake for the lab handouts) and release the materials under the same license.

Presentations On This Material

I have given a few presentations on this material and the links below provide access to my presentation materials.

Todd K. Timberlake (