Why Is the Sky Blue?

Air is invisible, so why is the sky blue? Sunlight looks white, but it's really a mixture of every colour. When it enters our atmosphere, tiny nitrogen and oxygen molecules scatter short blue waves about 5–6 times more strongly than long red ones. That scattered blue light reaches your eyes from every direction, so the whole sky glows blue. In this video: why it's not the ocean, why the sky isn't violet, why sunsets turn red, why clouds are white, why the Harmattan turns Nigeria's sky pale, why the sky is black on the Moon, why Mars has blue sunsets, why the ocean is blue, and a milk-and-torch experiment you can try at home. Chapters 00:00 Air is invisible... so why is the sky blue? 00:22 Two wrong answers 00:58 Sunlight is a hidden rainbow 01:56 Tiny obstacles in the air 03:32 Wait, why not violet? 04:11 Why sunsets turn red 05:07 The deeper story 07:08 Wait... really? Why the ocean is blue 07:44 Try it yourself 08:16 So why is the sky blue? Sources: Rayleigh (1871), "On the light from the sky, its polarization and colour"; Einstein (1910), Annalen der Physik 33; NASA Space Place, "Why Is the Sky Blue?"; Met Office; NOAA; NASA/JPL-Caltech PIA19400 (Mars sunset, 2015); Braun & Smirnov (1993), "Why Is Water Blue?", J. Chem. Educ. 70; Nigerian Meteorological Agency (Harmattan). EDUGALAXY -- Explore. Understand. Discover. #Science #Physics #Sky #Light #EduGalaxy