How Big is Our Galaxy - And How Do We Know？ - video Dailymotion

Science is Future

The Milky Way is ENORMOUS… but how do we know how big it is?   How do you figure out how far a star is?   The Milky Way has over 100 billion stars in it and we’re still learning new things about it all the time.   For more optimistic science and tech stories, subscribe!   #shorts #milkyway #science #stem #astrophysics

Transcript

00:00Our galaxy is enormous. It's 100,000 light years wide.

00:05Just think for a second about how big our galaxy really is.

00:08To really understand that, it's only 8.3 light minutes from the Sun to Earth.

00:12One light day would take you way beyond our solar system.

00:16But hang on, if we're here, how do we know how big our galaxy is?

00:19Well, we started measuring the distances to different stars, and by filling in this map,

00:23we discovered that there are way more that way and that way than that way and that way.

00:27So we understood its shape.

00:29But how do you figure out how far away a star is?

00:31This is cool.

00:32For the close ones, we can measure their apparent location in the sky,

00:35and then measure it again six months later when the Earth is on the other side of the Sun.

00:38And based on their slight change in location, we can calculate how far away it is.

00:42For farther stars, we look at a special category that pulse at a consistent rate.

00:46We know the ones that pulse faster are actually smaller and less bright,

00:49and our galaxy has 100 billion stars in it.

00:52We're learning new things about them all the time.

00:54If you want more optimistic science and tech stories, subscribe.

How Big is Our Galaxy - And How Do We Know？

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