galaxy several hundred years ago. Although the Crab Nebula is more than 10,000 times closer to us than M82, its filaments are much more difficult to see. Thus, if the structures in M82 were also created in an explosion, it must have been so vast that it disrupted the entire galaxy.
Movement of the hot gas traced by the H alpha emission seems at first to support the explosion theory. The gas appears to be expanding out from the center of M82 at velocities up to 1,000 kilometers per second. A central explosion might have ejected it from the galaxy at such speeds, but more recent studies suggest another explanation. Sensitive images of the H alpha light emission from the extended filaments have
