4 ms·
Milky Way is every 200 million years, as every school child knows: "The sun, and you and me, and all the stars that we can see Are moving at a million miles a
by isostatic 9y ago
Milky Way is every 200 million years, as every school child knows:
"The sun, and you and me, and all the stars that we can see
Are moving at a million miles a day
In an outer spiral arm at forty thousand miles an hour
Of the galaxy we call the Milky Way
Our galaxy itself, contains a hundred billion stars
It's a hundred thousand light years side-to-side
It bulges in the middle, sixteen thousand light years thick
But out by us its just three thousand light years wide
We're thirty thousand light years from galactic central point
We go round every two hundred million years
And our galaxy is only one of millions of billions
In this amazing and expanding universe"
- The Galaxy Song.
- crispyporkbites 9y agois this a thing? please make this a thing
- petewailes 9y agoIt's a thing. Monty Python
- cl0ckt0wer 9y agohttps://www.youtube.com/watch?v=buqtdpuZxvk https://www.youtube.com/watch?v=buqtdpuZxvk https://xkcd.com/1053/ https://xkcd.com/1053/
- TileHalo 9y agohttps://www.youtube.com/watch?v=XfcC6FYyL4U https://www.youtube.com/watch?v=XfcC6FYyL4U EDIT: Stephen Hawking singing Galaxy song
- danbruc 9y agohttps://en.wikipedia.org/wiki/Galaxy_Song https://en.wikipedia.org/wiki/Galaxy_Song
- throwaway2048 9y agothe rotation of a galaxy isnt the same thing as the rotation of the stars contained within in. The rotation of the galaxy is measured by the rotation of arms/other features, which are due to a traveling density wave (think about how traffic speeds up/slows down)
- wyager 9y agoIf stars orbit faster than arms, doesn’t this mean that stars have to occasionally change which arm they’re in? How does that work - some sort of gradual re-clumping of stars?
- mkempe 9y agoYes, our solar system travels from arm to arm! while the overall shape of the galaxy remains. By the way, our transit between and into these galaxy arms is theorized to coincide with past mass-extinction events, across tens of millions of years.
- civilian 9y agoWhaaat! I never heard about the galaxy arm transit coinciding with mass extinction events. I'm about to google, but do you have a favored source?
- mkempe 9y agoI commented here 10 months ago https://news.ycombinator.com/item?id=14291004 https://news.ycombinator.com/item?id=14291004 in relation to "Mass Extinction and the Structure of the Milky Way (2013) (arxiv.org)"
- civilian 9y agoBut, the arms don't rotate either! There are some great animations here: https://en.wikipedia.org/wiki/Density_wave_theory https://en.wikipedia.org/wiki/Density_wave_theory The article was about stars on the edge of a galaxy. > “But regardless of whether a galaxy is very big or very small, if you could sit on the extreme edge of its disk as it spins, it would take you about a billion years to go all the way round.”
- civilian 9y agoThe observation is for stars at the _edge_ of the galaxy. Sol is not on the edge.