If you enjoy crosswords, or need to learn more about the word "observatories", these crosswords are for you. Learning a subject can be difficult. To ease the pain, hints are provided at the bottom of each page, though these are selected to prevent an engineered solution to the puzzle. The clues in this book are used under license or with permission, used under "fair use" conditions, used in agreement with the original authors, or are in the public domain. Definitions of terms can be found at www.websters-online-dictionary.org. All entries marked [WP] are adapted from articles created by contributors to Wikipedia.org, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) based on the headword. Please note that these entries are not full articles. For the full article associated with a given Wikipedia headword, the reader can simply go to www.wikipedia.org or www.websters-online-dictionary.org and type in the name of the topic to better understand the context of the entry; passages attributed to Wikipedia are exempt from any compilation or other copyright held by this book and can be freely used under the GFDL found at www.wikipedia.org. The full GFDL is reproduced at the end of the book after the solutions, and applies to each Wikipedia headword. Enjoy!