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: null -- 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: null Follow Phil on Twitter: https://twitter.com/badastronomer Crash Course is on Patreon! You can support us directly by signing up at http://www.patreon.com/crashcourse Want to find Crash Course elsewhere on the internet? Facebook - http://www.facebook.com/YouTubeCrashCourse Twitter - http://www.twitter.com/TheCrashCourse Instagram - https://www.instagram.com/thecrashcourse/ CC Kids: null -- PHOTOS http://en.wikipedia.org/wiki/Right_ascension#mediaviewer/File:Stars_and_ra.png http://en.wikipedia.org/wiki/File:Ecliptic_path.jpg http://commons.wikimedia.org/wiki/File:Sagittarius_Hevelius.jpg http://en.wikipedia.org/wiki/Scorpius#mediaviewer/File:Sidney_Hall_-_Urania%27s_Mirror_-_Scorpio.jpg http://en.wikipedia.org/wiki/Libra_(constellation)#mediaviewer/File:Sidney_Hall_-_Urania%27s_Mirror_-_Libra.jpg http://en.wikipedia.org/wiki/Virgo_(constellation)#mediaviewer/File:Sidney_Hall_-_Urania%27s_Mirror_-_Virgo.jpg http://commons.wikimedia.org/wiki/File:Leo_Hevelius.jpg http://en.wikipedia.org/wiki/Cancer_(constellation)#mediaviewer/File:Sidney_Hall_-_Urania%27s_Mirror_-_Cancer.jpg http://en.wikipedia.org/wiki/Globe#mediaviewer/File:GEO_Globe.jpg http://sailornanny.weebly.com/uploads/1/0/5/0/10509307/4835516_orig.gif http://www.slate.com/content/dam/slate/blogs/bad_astronomy/2013/04/28/earth_elliptical_orbit.jpg.CROP.original-original.jpg http://en.wikipedia.org/wiki/Pole_star#mediaviewer/File:Precession_N.gif