Copyright Notice

These web documents and the hardcopy textbooks were created by Nick Strobel for the introductory science courses he teaches. The text of these documents (chapters) and all of the line drawings in them are copyrighted by Nick Strobel. Many of the color photographs are copyrighted by other parties. Their copyrights are noted with the images---usually the photo is linked to the original source if it is still available.

That said, I do offer the web documents and my line drawings and my photographs to the net as a resource in astronomy education. Feel free to use the web documents and (Strobel) original art in your own astronomy courses or talks. If you decide to make copies of these web documents on your web server, please observe all of the following rules:

  1. You must leave this notice of authorship with your copies;
  2. At the top of EACH page, add this notice:

    This page was copied from Nick Strobel's Astronomy Notes. Go to his site at for the updated and corrected version.

    The following html code will do that:
    <center><h4>This page was copied from
     <a href="">Nick Strobel's Astronomy Notes</a>.
    Go to his site at <a href=""></a>
    for the updated and corrected version.</h4></center>
  3. EACH page must also include the ``Is this page a copy of Strobel's Astronomy Notes?'' link at the bottom and a local copy of the isitacopy.htm web page.
  4. Check for updates to any pages frequently.

If you make hardcopies of these web documents or use any parts therein created by me including line drawings or my other original art in hardcopy or electronic format, you must clearly and explicitly acknowledge my authorship of the text and the images I created. Also, show how to get to my web site at For images, something like "This image is courtesy of Nick Strobel at" is sufficient. If you use the image on your website, send me the link to your website. If you use the image in a physical work you are creating such as a book, pamphlet, music album, paper, play, etc., I request that you send me a copy of the work when it is finished as "payment" for using the image.

Copyrighted, 1998 - 2020 [or current year] by Nick Strobel

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Author: Nick Strobel