Welcome to the AST 309-TIME
Home Page

You may send me an E-mail message right now, if you have any questions or comments about the course.

Here is a link to my Home Page. From it you can also locate other information about astronomy on the worldwide web. There is information about our department, about McDonald Observatory, and links to other astronomical pages.

This page is under construction. Keep tuned for new material.

You can access the grades on your papers and quizzes through UT Direct. You will need your UT EID and password.


The Final Exam will be held on Wednesday, December 10, from 9 AM-12 Noon in PAINTER 3.02. That's PAI 3.02. It is NOT our usual classroom, so don't go there! Bring your calculator, your astrolabe, and a note sheet for the entire course on ONE SIDE of an 8 1/2x11" sheet of paper, hand written as usual. It will count 10% of the grade on the final exam.

TENTATIVE GRADES including all your work except for the final will be posted before Wednesday, December 10, so that you can decide whether you need to take the final exam. If you don't take the final, your grade will be as posted at that time. If you do take the final, your grade may change upwards. It will NOT go down, i.e., taking the final can only improve your final grade, it cannot hurt it.

The third quiz will be held on December 4. The study list for the third quiz can be accessed here.

The second quiz will be on November 4. The study list for the second quiz can be accessed here.

The first quiz was on October 2. The study list for the first quiz can be accessed here.


The last time I taught this course, I found that a website published nearly verbatim copies of my notes on its website, in direct violation of the copyright notice at the end of this page. Please be assured that I will take legal steps to prevent such unauthorized publication of this material. Then notes for this course are more complete than the pirated notes were and should be more useful to you than any pirated notes might be.

A Note about Web Browsers

I find that Microsoft Internet Explorer does a better job of printing out these pages than does Netscape Navigator. Navigator seems to have a bug and sometimes leaves out sections of text after a picture. So I urge you to get a copy of Internet Explorer and use that in preference to Navigator.

Click here to enter Microsoft's Software Download Page. Be sure to select the correct version for your machine.

Course material



Sidereal and Synodic Periods
What is the day of the week?
Julian Day Calculations
Telling Time by the Stars
What is the age of the Moon?


Model of the Visible Planets DUE on September 11
Clock Comparison Project DUE on October 16
The Sundial DUE on October 7
Astrolabe Assigment DUE on October 21

Extra-credit projects (Due December 5, 2003)

Sunset Observations
Noon Fix
Observing the Moon


Course Outline
What is Time?
Motion of the Planets
Periods and Cycles [And also a supplemental chart]
Solar Calendars
Lunar Calendars
Maya Calendar
Sundial Time
The Astrolabe
Universal Time
Astronomical and Geological Clocks
Relativity I
Relativity II
Relativity III
General Relativity


To access the Spring, 2000 set of lectures, click here.

Important Note: To view the charts for this year's class, you will need to have a copy of Acrobat Reader installed on your machine. This can be downloaded free from Adobe Systems. Please follow the installation instructions on that page. In your browser, set the "helper application" for the extension .pdf (portable display format) to "Acrobat Reader." With Acrobat Reader installed, you will be able to view the lecture notes exactly as I showed them in class.

I have saved the charts as 4-up pages. This means that each page has miniature versions of four of the charts shown in class (this is an ideal size for reading, though Acrobat Reader will let you blow them up if you want to see more detail). You can print them out in advance of class and you may find them useful in saving you time copying things down. You can also save the documents on a floppy disk or your hard disk for later viewing with Acrobat Reader.

I find that the pages print best at 95% of full size. On a Mac, use the Page Setup menu; on PCs you'll have to figure out how to do it yourself!


I got E-mail from some students, with some interesting information on software for setting your PC by an atomic clock. There is similar software for the Mac. Other software of interest to the class was also mentioned.

Phil Plait's Bad Astronomy website is very entertaining. It has a number of examples of mistakes and confusions about astronomy that are popular, have been seen in the press, etc.

AtomTime95 for the PC sets your PC clock to an atomic standard. $5 shareware.

For the Mac, you can use Network Time, which is free and available from Chris Johnson's Mac Software Site at the University of Texas

MoonPhase for the PC is $3 shareware, displays the Moon's current phase (see also Observing the Moon for a web page that will do the same thing).

Lunar Ephemeris is similar and runs on the Mac.

At the same site there is more software that runs on the Mac and is related to time. Click here.

Aztec Calendar is available in both Mac and Windows versions. It displays the Aztec Calendar and allows you to convert dates to ordinary dates.

I thank the students who provided this information! This is an example of the sort of things that I hope that people will be posting to the listserv, and I certainly hope that more people will sign onto the listserv and contribute. Just send an E-mail message to requests@quasar.as.utexas.edu with the single line 'subscribe' (but delete the apostrophes). You will get a confirmation message back which you can respond to by just hitting the Reply button and sending the message off. If you have difficulty, send E-mail directly to me and I will subscribe you manually.

Suggested Readings on Time

Peter Coveney and Roger Highfield, The Arrow of Time: A Voyage Through Science to Solve Time's Greatest Mystery, Fawcett/Columbia.

John Gribbin, Schroedinger's Kittens and the Search for Reality, Little Brown & Co.

Heinz R. Pagels, Perfect Symmetry: The Search for the Beginning of Time, Bantam Books.

Huw Price, Time's Arrow and Archimedes' Point: New Directions for the Physics of Time, Oxford University Press.

Clifford M. Will, Was Einstein Right? Putting General Relativity to the Test, Basic Books.

Web Resources

Here are some useful web pages that I've found that have to do with time and astronomy.

NASA's Jet Propulsion Laboratory puts out a Space Calendar with lots of useful information.

A Walk Through Time is a series of web pages that cover many of the topics of this course. I recommend it highly. It is maintained by the National Institute of Standards and Technology (NIST)'s Time and Frequency Division of Physics Laboratory

Here's a neat website that allows you to find your latitude and longitude on a map, by pointing and clicking.

Joe Heafner's Tons O' Astronomy Links contains a large number of useful links, many of which are directly relevant to this course.

A student in our class suggests looking at this calendar page for information on calendars from around the world. Indeed, there is a lot of information here on all sorts of calendars, far more than we could ever cover in class. The page is listed in Lycos' "Top 5% of the Web." Check it out!

A List of Frequently Asked Questions about Calendars gives a great deal of information about many calendars.

A list of links to sundial sites around the world can be found at Sundial Links. This site contains links to pictures of sundials, astrolabes, nocturnals, etc., as well as to discussions of various kinds of sundials and other useful information. 

Directorate of Time is run by the United States Naval Observatory. It has a lot of neat things, including a page that will serve you sunrise, sunset, moonrise and moonset times, information on atomic time, on the LORAN, OMEGA, and GPS systems, a time server that will connect you with the U.S. Naval Observatory's master clock and serve you the up-to-the-second time, and a history of the U.S. Naval Observatory's 150 years of time-keeping.

Department of Commerce Self-Tour is a series of pages that will introduce you to the National Institute of Standards and Technology (NIST, formerly the National Bureau of Standards, or NBS) and its timekeeping services in Boulder, CO; this is where some of the atomic clocks that are used as the world's time standards are kept. There are pictures of atomic clocks and a sample of what the time service WWV sounds like.

Here are some more resources on the Global Positioning System (GPS). This is a satellite system that gives position and time, using small, inexpensive handheld receivers. It is a wonderful example of how modern timekeeping technology is making a whole new range of possibilities available to everyday life. There is an article on GPS in the February issue of Scientific American.. Here are some worldwide web pages that will tell you more about it:

GLONASS is the Russian equivalent of GPS. There are some differences (in particular, there is no Selective Availability). MIT's Lincoln Labs maintains a web page on Glonass.

Science and Stonehenge is a site that contains a lot of information about Stonehenge, including a page Dating Stonehenge that dicusses modern attempts to date the site. These sites didn't work when I tried them recently, but they are still listed on one of the search engines. Try them anyway.

For fun, you can also look at the website Carhenge, which is a knock-off of Stonehenge.

A more general site discussing dating of archaeological sites by the radiocarbon method can be found at Radiocarbon WEB-info. All aspects of the method are covered, from basic principles through tricky questions such as calibration by tree-ring dating (dendrochronology).

Here is a link to the Space Telescope Science Institute. They have lots of pictures from the Hubble Space Telescope, and new pictures are put up there almost every day.

Need a star chart of some part of the sky? Here's a page that will custom-make a star chart for you. You'll need a PostScript printer to print it out. If you want to try it out, click here.

This page was served to you by Quasar, a PowerMac 7300/180. It was last modified on 031202.
My home page is located here.

All materials at this website Copyright (C) 1996-2003 by William H. Jefferys. All Rights Reserved.