Before moving on from Jupiter to Saturn, we’re going to linger for a moment on Jupiter’s moons. There are 67 known moons, and 4 huge ones that we want to explore in greater detail. Ganymede is the largest - larger, in fact, than any other moon in the solar system and the planet Mercury! Callisto, orbiting the farthest out, is smaller but quite similar to Ganymede in many ways. Io, meanwhile, is most noteworthy for its tremendous volcanic activity. There’s also water on Ganymede and Europa!

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Table of Contents
Jupiter Has 67 Moons (4 Big Ones) 0:12
Ganymede is the Largest 1:15
Io is Riddled With Volcanoes 3:16
Europa Has an Undersurface Ocean 4:48
Io, Europa, and Ganymede Interact Gravitationally 3:48
Known Unknowns 8:06

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PHOTO/VIDEO SOURCES
Galileo’s notebook hos.ou.edu/exhibits/exhibit.php?exbid=4 [credit: Image(s) courtesy History of Science Collections, University of Oklahoma Libraries; copyright the Board of Regents of the University of Oklahoma.]
Jupiter’s moons photojournal.jpl.nasa.gov/jpeg/PIA00600.jpg [credit: NASA/JPL/DLR]
Ganymede svs.gsfc.nasa.gov/vis/a010000/a011100/a011173/Image4_1920x1080.jpg [credit: NASA/JPL/Ted Stryk]
Interior of Ganymede commons.wikimedia.org/wiki/File:PIA00519_Interior_of_Ganymede.jpg [credit: Wikimedia Commons / NASA]
Ganymede terrain commons.wikimedia.org/wiki/File:Ganymede_terrain.jpg [credit: Wikimedia Commons / NASA]
Artist Conception of Ganymede www.nasa.gov/content/goddard/hubbles-view-of-ganymede-briefing-materials/ (Figure 5) [credit: NASA/ESA]
Callisto photojournal.jpl.nasa.gov/jpeg/PIA03456.jpg [credit: NASA/JPL/DLR]
Interior of Callisto en.wikipedia.org/wiki/Callisto_(moon)#/media/File:PIA01478_Interior_of_Callisto.jpg [credit: Wikimedia Commons / NASA]
Valhalla crater on Callisto commons.wikimedia.org/wiki/File:Valhalla_crater_on_Callisto.jpg [credit: Wikimedia Commons / NASA / JPL]
Io svs.gsfc.nasa.gov/vis/a010000/a011400/a011455/s1-1920.jpg [credit: NASA/JPL/USGS]
Io volcano image solarviews.com/browse/jup/ioplumedisc.jpg [credit: NASA/JPL]
Io eruption video svs.gsfc.nasa.gov/vis/a010000/a011400/a011455/IO_Eruption-540-MASTER_high.mp4 [credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute]
Io surface svs.gsfc.nasa.gov/vis/a010000/a011400/a011455/s2-1204.jpg [credit: NASA/JPL/University of Arizona]
Jupiter Magnetosphere Schema en.wikipedia.org/wiki/Io_(moon)#/media/File:Jupiter_magnetosphere_schematic.jpg [credit: Wikimedia Commons / Volcanopele]
Jupiter aurora www.spacetelescope.org/static/archives/images/large/heic0009a.jpg [credit: NASA, ESA & John T. Clarke (Univ. of Michigan)]
Europa photojournal.jpl.nasa.gov/jpeg/PIA19048.jpg [credit: NASA/JPL-Caltech/SETI Institute]
Europa ocean apod.nasa.gov/apod/image/1205/EuropasOcean_KPHand003.jpg [credit: NASA/JPL/Kevin Hand
Habitable zone diagram www.keckobservatory.org/images/made/images/gallery/solar_system/Slides-8_1800_1350.jpg [credit: PETIGURA/UC BERKELEY, HOWARD/UH-MANOA, MARCY/UC BERKELEY]
Amalthea photojournal.jpl.nasa.gov/jpeg/PIA02532.jpg [c redit: NASA/JPL/Cornell University]

1. Introduction to Astronomy
2. Naked Eye Observations
3. Cycles in the Sky
4. Moon Phases
5. Eclipses
6. Telescopes
7. The Gravity of the Situation
8. Tides
9. Introduction to the Solar System
10. The Sun
11. The Earth
12. The Moon
13. Mercury
14. Venus
15. Mars
16. Jupiter
17. Jupiter's Moons
18. Saturn
19. Uranus & Neptune
20. Asteroids
21. Comets
22. The Oort Cloud
23. Meteors
24. Light
25. Distances
26. Stars
27. Exoplanets
28. Brown Dwarfs
29. Low Mass Stars
30. White Dwarfs & Planetary Nebulae
31. High Mass Stars
32. Neutron Stars
33. Black Holes
34. Binary and Multiple Stars
35. Star Clusters
36. Nebulae
37. The Milky Way
38. Galaxies, part 1
39. Galaxies, part 2
40. Gamma-Ray Bursts
41. Dark Matter
42. The Big Bang, Cosmology part 1
43. Dark Energy, Cosmology part 2
44. A Brief History of the Universe
45. Deep Time
46. Everything, The Universe...And Life
47. Explore The Solar System:

In this Crash Course series, marvel at the wonders of astronomy with your host for this intergalactic adventure, the Bad Astronomer himself -- Phil Plait. In just 40 short lessons, you will learn the basics of the oldest science known to humanity.

Be sure to check out links to relevant Photos in the description for each video.