January 31, 2012 / Nature / 1 comment 
The usual definition of what a galaxy is: ‘An island universe’, or ‘A vast collection of stars’ is not wrong, but it is misleading. Because of the vast distances that separate stars even in the most densely packed regions of most galaxies, a better definition is: ‘A vast formation of plasma clouds that contain electrical currents and occasional, widely distributed tiny lumped points of matter called nebulae, stars and planets.’ The shape that characterizes most galaxies was first described by Hannes Alfven in 1981. Take a trip across the universe and check out these amazing photos of stars and galaxies. Enjoy.
