Now that we’re done with the planets, asteroid belt, and comets, we’re heading to the outskirts of the solar system. Out past Neptune are vast reservoirs of icy bodies that can become comets if they get poked into the inner solar system. The Kuiper Belt is a donut shape aligned with the plane of the solar system; the scattered disk is more eccentric and is the source of short period comets; and the Oort Cloud which surrounds the solar system out to great distances is the source of long-period comets. These bodies all probably formed closer into the Sun, and got flung out to the solar system’s suburbs by gravitational interactions with the outer planets.

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Table of Contents
Icy Bodies That Can Become Comets 0:27
The Kuiper Belt is a Donut Shape Aligned With the Plane of the Solar System 2:57
The Scattered Disk is More Eccentric and the Source of Short Period Comets 4:26
Oort Cloud Surrounds Our Solar System and is the Source of Long-Period Comets 4:04
These Bodies Probably Formed Near the Sun and Dispersed Through Gravitational Interactions 5:41

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PHOTOS/VIDEOS
HD Long Exposure Star Timelapse vimeo.com/34172172 [credit: Jeffrey Beach, Beachfront B-Roll]
Fine Structure in the Comet’s Jets blogs.esa.int/rosetta/2015/01/16/fine-structure-in-the-comets-jets/ en.wikipedia.org/wiki/Protoplanetary_disk#mediaviewer/File:Artist%E2%80%99s_Impression_of_a_Baby_Star_Still_Surrounded_by_a_Protoplanetary_Disc.jpg [credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA]
Artist's impression of a protoplanetary disk. [credit: ESO/L. Calçada - ESO]
Creating Gas Giants svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=11541 [credit: NASA's Goddard Space Flight Center]
What is a Sungrazing Comet? svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=11307 [credit: NASA's Goddard Space Flight Center]
Pluto/Neptune Orbit www2.jpl.nasa.gov/files/images/browse/plutoneptune.gif [credit: NASA]
1992 QB1 solarsystem.nasa.gov/multimedia/gallery/1992_QB14.jpg [credit: ESO]
Eris apod.nasa.gov/apod/ap060918.html [credit: W. M. Keck Observatory]
Moons of Pluto en.wikipedia.org/wiki/Kerberos_(moon)#/media/File:Moons_of_Pluto.png [credit: NASA, ESA, and M. Showalter (SETI institute)]
New Horizons Approach pluto.jhuapl.edu/common/content/animations/New-Horizons-Voyage-to-Pluto/ApproachingPluto1280.mp4 [credit: JHUAPL]
Moon svs.gsfc.nasa.gov/vis/a000000/a003800/a003894/phase04_full.jpg [credit: NASA/Goddard Space Flight Center Scientific Visualization Studio]
Pluto solarsystem.nasa.gov/multimedia/display.cfm?Category=Planets&IM_ID=20073 [credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute]
Sedna’s Orbit commons.wikimedia.org/wiki/File:Sedna-PIA05569-crop.jpg [credit: NASA]
Artist’s Conception of Kuiper Belt en.wikipedia.org/wiki/File:14-281-KuiperBeltObject-ArtistsConcept-20141015.jpg [credit: NASA, Wikimedia Commons]
Kuiper Belt World (video) planetquest.jpl.nasa.gov/video/41 [credit: NASA Kepler Mission/Dana Berry]
Pluto Discovery Plates azmemory.azlibrary.gov/cdm/singleitem/collection/loaselect/id/25/rec/1 [credit: Clyde Tombaugh, Lowell Observatory]

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.