Mercury is the closest planet to the sun. It has no atmosphere and is, as such, covered in craters. It's also incredibly hot but, surprisingly, has water ice hiding beneath its surface.

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Table of Contents
Closest Planet to the Sun 0:03
Rotation Locked to its 2 to 3 Orbit Ratio 3:10
Deep Crater Water Ice 8:39

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PHOTOS/VIDEOS
Mercury relief in Olomouc: commons.wikimedia.org/wiki/File:Mercury_relief_in_Olomouc.jpg [credit: Michal Maňas]
Mercury: Phil Plait
Mercury in color: en.wikipedia.org/wiki/File:Mercury_in_color_c1000_700_430.png [credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington]
Earth Based View of Mercury: airandspace.si.edu/explore-and-learn/multimedia/detail.cfm?id=3726 [credit: Catalina Observatory]
Caloris Basin: apod.nasa.gov/apod/image/1503/PIA19216MessengerCaloris.jpg [credit: NASA, Johns Hopkins Univ. APL, Arizona State U., CIW]
MESSENGER photos:
messenger.jhuapl.edu/gallery/sciencePhotos/pics/EW1010234404_500_web.jpg
messenger.jhuapl.edu/gallery/sciencePhotos/pics/EN0108830230M.jpg
messenger.jhuapl.edu/gallery/sciencePhotos/pics/EW0224377798G.nomap.png
[credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington]
Mercury’s core: astrosun2.astro.cornell.edu/~jlm/out/Mercury/mercury_NSF_printsize.jpg [credit: Nicolle Rager Fuller, National Science Foundation]
Mercury’s Ice Lockers: svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=11184 [credit: NASA Goddard Space Flight Center/Massachusetts Institute of Technology/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington]
Mercury’s Tail: geeked.gsfc.nasa.gov/wp-content/uploads/2011/03/Mercury_exosphere_600-full.jpg [credit: NASA]

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.