Astronomy Picture of the Day . Red Sun Streaming . ... Some of these particles strike the Earth and cause aurora. ... The Sun is a bubbling ball of extremely hot gas. ... On the left is a normal star field containing the constellation Orion. ... A Wolf-Rayet Star Blows Bubbles . ... Wolf-Rayet stars can blow bubbles. These unusual stars are much hotter and more luminous than our Sun. ... Wolf-Rayet stars generate bubbles because they continually eject their outer atmosphere as a stellar wind. ...