Today Phil explains that YES, there are other planets out there and astonomers have a lot of methods for detecting them. Nearly 2000 have been found so far. The most successful method is using transits, where a planet physically passes in front of its parent star, producing a measurable dip in the star’s light. Another is to measuring the Doppler shift in a star’s light due to reflexive motion as the planet orbits. Exoplanets appear to orbit nearly every kind of star, and we’ve even found planets that are the same size as Earth. We think there may be many billions of Earth-like planets in our galaxy.

This is a reupload of last week's episode to correct an error in the way we covered reflexive motion.
For more information on the change and reflexive motion, you can check out Phil's blog: www.slate.com/blogs/bad_astronomy/2015/08/07/crash_course_astronomy_exoplanets.html
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Table of Contents
Other Planets Orbit Other Stars 2:10
Nearly 2000 Have Been Found 9:29
Transits 5:44
Doppler Shift 3:30
Exoplanets Orbit Nearly Every Kind of Star 8:44
Billions of Earth-Like Planets 9:33

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PHOTOS/VIDEOS
Stars as viewed from ISS www.youtube.com/watch?v=TOQrx-7qgak [credit: Alex Rivest & NASA]
Jupiter www.nasa.gov/centers/goddard/multimedia/largest/Jupiter_sphere.jpg.html [credit: NASA]
Mars mars.jpl.nasa.gov/multimedia/images/?ImageID=2633 [credit: NASA/JPL-Caltech/MSSS]
Mercury solarsystem.nasa.gov/multimedia/display.cfm?Category=Planets&IM_ID=7543 [credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington]
Earth www.nasa.gov/topics/earth/overview/index.html [credit: NASA]
Uranus photojournal.jpl.nasa.gov/catalog/PIA18182 [credit: NASA/JPL-Caltech]
Lost in the Glare planetquest.jpl.nasa.gov/video/23 [credit: NASA Kepler Mission/Dana Berry]
Reflexive Motion gifs spaceplace.nasa.gov/barycenter/en/ [credit: NASA]
Artist's conception of PSR B1257+12's system of planets en.wikipedia.org/wiki/Pulsar_planet#/media/File:Artist%27s_concept_of_PSR_B1257%2B12_system.jpg [credit: NASA/JPL-Caltech/R. Hurt (SSC)]
Artist’s impression of the exoplanet 51 Pegasi b (image) www.eso.org/public/usa/images/eso1517a/ [credit: ESO/M. Kornmesser/Nick Risinger (skysurvey.org)]
Artist’s impression of the exoplanet 51 Pegasi b (video) www.eso.org/public/usa/videos/eso1517b/ [credit: ESO/M. Kornmesser/Nick Risinger (skysurvey.org)]
Kepler Transit Graph planetquest.jpl.nasa.gov/video/22 [credit NASA Kepler Mission/Dana Berry]
Kepler “Beauty Shot” planetquest.jpl.nasa.gov/video/2 [credit: NASA/Kepler mission/Dana Berry]
The Brown Dwarf 2M1207 and its Planetary Companion www.eso.org/public/usa/images/eso0515a/ [credit: ESO]
Beta Pictoris b www.eso.org/public/archives/images/screen/eso1024c.jpg [credit: ESO]
A size comparison of the planets in the Kepler-37 system and objects in the Solar System photojournal.jpl.nasa.gov/catalog/PIA16694 [credit: NASA/Ames/JPL-Caltech]
Water World planetquest.jpl.nasa.gov/video/39 [credit: NASA Kepler Mission/Dana Berry]
Earth-like World planetquest.jpl.nasa.gov/video/42 [credit: NASA Kepler Mission/Dana Berry]

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.