Watch Episode #4 of Neil deGrasse Tyson’s Cosmos: The Big Bang, Black Holes & More (US Viewers)

On Sun­day evening, Fox aired the lat­est episode of Neil deGrasse Tyson’s Cos­mos series. This episode, called “A Sky Full of Ghosts,” explored some more out-of-this-world sub­jects — the speed of light and how it helps us under­tand the Big Bang; the sci­en­tif­ic work of Isaac New­ton, William Her­schel, James Clerk Maxwell; Albert Ein­stein’s The­o­ry of Rel­a­tiv­i­ty; dark stars; black holes; and more. US view­ers can watch the entire­ty of Episode 4 online (above), along with pre­vi­ous episodes in the series below (or on Hulu). For view­ers out­side the US, we have some­thing per­haps bet­ter for you: Carl Sagan’s Orig­i­nal Cos­mos Series on YouTube. Plus, we have a bunch of Free Online Astron­o­my Cours­es in our col­lec­tion of 875 Free Online Cours­es. Enjoy.

Pre­vi­ous Episodes:

Episode #1: “Stand­ing Up in the Milky Way”

Episode #2: “Some of the Things That Mol­e­cules Do”

Episode #3: “When Knowl­edge Con­quered Fear”