Dinosaurs

Milky Way Rotation

Never thought of it that way before. Kind of puts the invention of lignin (360 million years ago) and the development of lignin eating bacteria (300 million years ago) in perspective.

If the Milky was actually rotating, you might think that all the stars in the Milky Way would just head off into the great beyond. Pictures of spiral arm galaxies sure look like they are rotating, though I can never decide whether they are winding up the spiral arms (clockwise in the above picture) or flying apart (counter-clockwise). But then there is gravity. Hard to believe that it could exert any noticeable force over a distance of 25,000 light years.

All of which got me to wondering how fast the Sun is traveling, so off to the spreadsheet.


Satellites in low earth orbit, like the International Space Station, travel around 5 miles per second. The earth is traveling around the sun at 19 miles per second, so the sun traveling at 130 miles per second has got the hammer down. Except all our neighbors are going the same way at the same rate. Except for Barnard's Star, which is hustling along at 57 miles per second relative to the sun, going who knows where.

Via dad's deadpool blog