revealed that the nebulaΓÇÖs arms are moving outward, obscuring more and more stars over time. The speed of the movementΓÇö1,000 kilometers per second, even after 900 yearsΓÇö indicates the immense strength of the explosion that gave birth to the Crab Nebula.
The nebulaΓÇÖs dual structure is also apparent here: the intricate filamentary network that gives it its name appears to be superimposed over a diffuse, almost formless cloud of gas. The various colors of light emanating from the nebula are mostly generated by ionized atoms. Each color corresponds to a particular type of atom at a particular temperature and stage of ionization. Red light represents un-ionized hydrogen atoms, and white light a spectral continuum of
