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Saturn from Cassini Astronomy 161:
An Introduction to Solar System Astronomy
Prof. Richard Pogge, MTWThF 9:30

Copyright Statement

All of the written material and some of the graphics (static images and animations), and all of the audio lecture recordings on these pages are copyrighted by Richard W. Pogge unless otherwise noted, and may not be reproduced without written permission.

Educational or non-profit organizations wishing to reproduce or provide links to any part of these pages must contact Richard Pogge ( in writing. Please see the Usage Guidelines below for specific information and terms before contacting me.

Usage Guidelines

These web pages are intended primarily for use by Ohio State University students enrolled in Astronomy 161. Students formally enrolled in this course are granted permission to make copies of the online notes in unaltered form for exclusive personal use only, provided that all copyright notices and citations of images and text sources remain intact. "Personal Use", however, does not extend to additional reproduction, alteration, distribution, or resale of these notes in any form to anybody. Your use of these web pages implies that you agree with and will respect these conditions of use.

All other interested persons who are not enrolled in this course at The Ohio State University are welcome to browse these pages, provided that they observe the following usage restrictions:

  1. Educators, educational organizations, or registered non-profit organizations may link to these pages from their websites, but they are expressly prohibited from copying any of the material on these pages, in whole or in part, to their own websites, making translations into other languages, or making copies for distribution in any non-web form, electronic or physical. Graphics may not be copied without written permission from the author, Richard Pogge ( This permission gives me a record of who is using this material outside of The Ohio State University. Any graphics that are copied and inserted into online documents must include a full citation as to their source, including a link back to the page with the original context. This serves two important purposes: it makes clear to your readers the provenance of a graphic, and it relieves you of responsibility for responding to queries about that graphic by others.

  2. You may not reproduce, distribute, translate into another language, or resell any of the materials on these pages in any form, nor may you charge others to gain access to these pages. In particular, you are specifically prohibited from including any of the written material or graphics, in whole or in part, in course note or lecture note packages compiled with the intention of reselling them to students enrolled in this or related courses at this or any other educational institutions. This includes providing copies of these notes, in whole or in part, to electronic note-taking services.

  3. Citations of factual material in these pages should be to the original literature sources. Please contact the author of these pages for information on the correct citation of particular materials, or if you see incorrect citations so that the author may correct these errors.

  4. All audio recordings of the lectures, whether obtained directly from this site or via podcasting services like iTunes, are Copyright © Richard Pogge, all rights reserved. You are allowed to make personal copies for your own listening on personal computers or other personal audio devices (including but not limited to mp3 players, iPods, or home audio receivers), but you may not share or otherwise distribute these audio files to others by any means. If others are interested in listening to these lectures, please direct them to the original sources (e.g., the RSS feed on this site or the iTunes portal), as access by those means increases their traffic and helps justify these services.
Note that by downloading any files from this site, you are implicitly agreeing to the above conditions.

A Brief Note About Copyrights

The precise relationship between existing copyright laws and publically accessible electronic documents on the Internet is a subject of considerable discussion and debate. Copyrights are an essential protection for teachers and students alike, as they play a fundamental role in helping to preserve the integrity of our intellectual activities (writing, images, etc.) by protecting our creative works from commercial exploitation by others. I take the issue of copyrights very seriously in the production of these web pages.

If you notice any inappropriately used or incorrectly cited text or images, please contact me so that I can either seek the proper use permissions or delete them from these pages (providing substitutions where possible).

Text Sources
I have made a good faith effort to be very careful about not including copyrighted text (other than my own) in these pages, except where I have sought specific permission from the original authors. I would appreciate help correcting any erroneous citations to primary sources you might spot in these pages.

Images are essential to teaching astronomy, and present a wide range of copyright issues in the context of the Internet. Since copyright law with regards to electronic graphics is still being developed, I have little guidance except common sense. As such, I use primarily public domain images on these pages, taking care to correctly cite the original sources, and have sought permission for other images (e.g., I have an agreement with the Anglo-Australian Observatory for use of some of their copyrighted images on these pages).

Some of the images and graphics displayed during my lectures are copyrighted materials unavailable in the public domain. While use of these images in lecture is permitted under the well-established principle of "Fair Use", that same principle prohibits me from posting these images to the Web without the explicit permission of the owner of their copyright. I am seeking permission from the original sources to post some of the graphics on these pages, but not all persons have granted that permission. For example, the publishers of the textbook have provided me with electronic copies of most of the graphics from the book which I may include in my lectures, but they do not grant me permission to post them on the class webpages. This can be somewhat inconvenient for the students, as a number of the images and graphics used in lecture are not otherwise available online, but it is unavoidable.

An exciting feature of electronic presentation is the ability to set some images into motion. In astronomy we often deal with dynamic phenomena: rotation, orbital motion, explosions, tidal encounters & collisions, etc., and static pictures do not convey the concepts as clearly as animations. We are beginning to create our own animations for these classes, and are putting them onto the web pages for the students to view (and play with) after class to help cement the ideas. All OSU-created animations are copyrighted and subject to the same restrictions noted above.

Some of the animations shown in class were created by others. In these cases, I have put in links to the original webpages from which I got them, or am seeking permission from the creators to make local copies available to try to help with the download time for my students. In all cases, these local copies are accompanied by links to the original sources, and you should always consult with the creators to seek permission to use them.

Audio Recordings ("Podcasts")
The increasing popularity of Apple's iPod portable music player and similar technologies has made it possible to make high-quality digital recordings of the lectures available to students online. Delivery of these recordings is greatly enabled by "Podcasting", an especially simple and powerful means of online multimedia content distribution. Students find the recordings helpful as study aids (and to make up lectures they missed because of illness or absense), and people outside the university have written telling me that they are listening to them for a wide variety of reasons (interest in the topic, "life-learning", make the daily commute less boring, etc.). The value of these recordings as a multifaceted study aid and public outreach tool is such that I will continue to make my lecture recordings publically accessible. However, these recordings do fall into some gray areas with regards to copyright and ownership of the content that are still being worked out. This is why I ask that listeners who like the recordings share them by directing others to the originals, rather than making copies. This lets me preserve the integrity of the original source material, and the additional traffic allows me to demonstrate to my Department and University that there is enough demand for the recordings to continue making computer and network resources available to host the materials online.
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Updated: 2016 January 12 [rwp]