Cosmology and astronomy
It's a great, big universe out there. In this section of Khan Academy, you'll learn about the brain-bending vastness of time and space. We go from plate tectonics here on Earth to entire galaxies and beyond.
4 units110 videos16 hours
Learn it live with a class on Puzzicle · Teachers: use it with your class
Unit 1: Scale of the universe
Scale of earth, sun, galaxy and universe
Time scale of the cosmos
Light and fundamental forces
Special relativity
Light and the luminiferous ether ✓ Check-ins7:58
Potential ways to detect an ether wind ✓ Check-ins7:24
Michelson–Morley Experiment introduction ✓ Check-ins8:12
Starting to set up a Newtonian path–time diagram ✓ Check-ins7:55
Visualizing multiple Newtonian path–time diagrams ✓ Check-ins9:38
Galilean transformation and contradictions with light ✓ Check-ins8:04
Introduction to special relativity and Minkowski spacetime diagrams ✓ Check-ins13:44
Measuring time in meters in Minkowski spacetime ✓ Check-ins4:58
Angle of x' axis in Minkowski spacetime ✓ Check-ins7:22
Introduction to the Lorentz transformation ✓ Check-ins8:21
Evaluating a Lorentz transformation ✓ Check-ins8:41
Algebraically manipulating Lorentz transformation8:01
Lorentz transformation derivation part 1 ✓ Check-ins10:55
Deriving Lorentz transformation part 2 ✓ Check-ins6:08
Lorentz transformation derivation part 3 ✓ Check-ins11:22
Lorentz transformation for change in coordinates ✓ Check-ins5:06
Einstein velocity addition formula derivation ✓ Check-ins7:36
Applying Einstein velocity addition ✓ Check-ins6:22
Finding an in-between frame of reference ✓ Check-ins8:12
Calculating neutral velocity ✓ Check-ins6:45
Time dilation ✓ Check-ins9:14
Big bang and expansion of the universe
Big bang introduction ✓ Check-ins11:03
Radius of observable universe ✓ Check-ins16:39
Radius of observable universe (correction) ✓ Check-ins2:14
Red shift ✓ Check-ins10:04
Cosmic background radiation ✓ Check-ins11:36
Cosmic background radiation 2 ✓ Check-ins10:15
Hubble's law ✓ Check-ins11:12
A universe smaller than the observable ✓ Check-ins8:58
Unit 2: Stars, black holes and galaxies
Life and death of stars
Birth of stars ✓ Check-ins7:58
Accreting mass due to gravity simulation ✓ Check-ins3:34
Becoming a red giant ✓ Check-ins11:30
White and black dwarfs ✓ Check-ins12:54
Star field and nebula images7:04
Lifecycle of massive stars ✓ Check-ins6:41
Supernova (supernovae) ✓ Check-ins11:58
Supernova clarification ✓ Check-ins1:32
Black holes ✓ Check-ins10:09
Supermassive black holes ✓ Check-ins9:28
Quasars and galactic collisions
Stellar parallax
Unit 3: Earth geological and climatic history
Plate tectonics
Plate tectonics: Difference between crust and lithosphere ✓ Check-ins7:59
Structure of the earth ✓ Check-ins9:33
Plate tectonics: Evidence of plate movement ✓ Check-ins13:18
Plate tectonics: Geological features of divergent plate boundaries ✓ Check-ins11:58
Plate tectonics: Geological features of convergent plate boundaries ✓ Check-ins6:04
Plates moving due to convection in mantle ✓ Check-ins6:02
Hawaiian islands formation ✓ Check-ins8:01
Pangaea ✓ Check-ins5:58
Compositional and mechanical layers of the earth ✓ Check-ins11:50
How we know about the earth's core ✓ Check-ins5:49
Seismic waves and how we know earth's structure
Earth's rotation and tilt
Seasons aren't dictated by closeness to sun ✓ Check-ins4:39
How Earth's tilt causes seasons ✓ Check-ins20:47
Are southern hemisphere seasons more severe? ✓ Check-ins7:17
Milankovitch cycles precession and obliquity ✓ Check-ins12:57
Precession causing perihelion to happen later ✓ Check-ins12:04
What causes precession and other orbital changes ✓ Check-ins2:06
Apsidal precession (perihelion precession) and Milankovitch cycles ✓ Check-ins7:07
Moon phases and eclipses
Unit 4: Life on earth and in the universe
History of life on earth
Humanity on earth
Human evolution overview ✓ Check-ins12:26
Understanding calendar notation ✓ Check-ins9:41
Correction calendar notation ✓ Check-ins4:12
Development of agriculture and writing ✓ Check-ins13:03
Firestick farming in early Australia ✓ Check-ins6:37
How symbolic language drives collective learning ✓ Check-ins13:17
Thomas Malthus and population growth ✓ Check-ins8:13
Agriculture and human population ✓ Check-ins13:00
Energy inputs for tilling a hectare of land ✓ Check-ins13:41
Random predictions for 2060 ✓ Check-ins11:07
Measuring age on earth
Learn this with a class
With a class on Puzzicle this course runs as a timetable of live study parties: your batch watches together and answers the check-ins, sometimes with a teacher leading.
Course content © Khan Academy, used under CC BY-NC-SA. See this course on Khan Academy.