Free movies

Cosmology: The History and Nature of Our UniverseAstronomers overlap techniques of "distance ladder" to determine distances in the universe; triangulation works for nearby stars; observers use pulsating stars for farther objects, the rotation of galaxies and a class of supernova explosions.

On now

Up next

Now PlayingCosmology: The History and Nature of Our UniverseAstronomers overlap techniques of "distance ladder" to determine distances in the universe; triangulation works for nearby stars; observers use pulsating stars for farther objects, the rotation of galaxies and a class of supernova explosions.0Cosmology: The History and Nature of Our UniverseMeasuring the Doppler shift of galaxies in the early 20th century; observations reveal that they all were moving away from Earth; the more distant ones move faster, proportional to distance; this is the Hubble Law, implying the initial "big bang."