This week we build on our naked eye observations from last week and take a look at the cyclical phenomena that we can see at work in the universe. Check out the Crash Course Astronomy solar system poster here: -- Chapters: Introduction 00:00 Cycles in the Sky 0:42 The Zodiac 2:10 Planetary Movement 2:59 The Earth's Axis 3:36 Precession 6:09 Things We've Learned From Naked Eye Observations 7:09 Review 8:40 -- PBS Digital Studios: Follow Phil on Twitter: Crash Course is on Patreon! You can support us directly by signing up at Want to find Crash Course elsewhere on the internet? Facebook - Twitter - Instagram - CC Kids: -- PHOTOS #mediaviewer/File: : : #mediaviewer/File:Sidney_Hall_-_Urania% (constellation)#mediaviewer/File:Sidney_Hall_-_Urania% (constellation)#mediaviewer/File:Sidney_Hall_-_Urania% : (constellation)#mediaviewer/File:Sidney_Hall_-_Urania% #mediaviewer/File: #mediaviewer/File: