Introduction to Astronomy: Crash Course Astronomy #1
Why the open web links it
Introduces astronomy, its purpose, and sets the stage for a broader exploration of the universe.
Linked by 26 independent sites, 2 of them widely read in the 2026-10 crawl of the open web, including csusm.edu, searchengines.guru, loe.org, davidsongifted.org, learningmole.com.