[00:02] here's how people first learned the distance to nearby galaxies. In a the brightness of a sing of a single star because there's just billions of there are some amazingly bright stars. They're called Sephi, the super giant
[00:16] brighter than the sun. Some of them live in our own galaxy and some of them live blend in, but but you can still kind of measure their brightness. These stars so most stars they stay the same intensity for all time but these sephied
[00:31] stars their their brightness oscillates so they have a period of intensity like every 20 days every 10 days they oscillate and it turns out that the the longer the period if a galaxy happen to have a seed in it you can just
[00:44] observe it work out its period that gave you intensity that know so now you know bright it looks you can measure it distance that gave the next rung of the ladder so a couple thousand galaxies where you can measure the distance. But
[00:59] that again is only a tiny portion of the universe.