Spectroscopic observations show that all planetary nebulae are expanding, and so the idea arose that planetary nebulae were caused by a star's outer layers being thrown into space at the end of its life.
This led to the idea arose that planetary nebulae were caused by a star's outer layers being thrown into space at the end of its life. Spectroscopic observations show that all planetary nebulae are expanding.
Spectroscopic observations show that all planetary nebulae are expanding. This led to the idea arose that planetary nebulae were caused by a star's outer layers being thrown into space at the end of its life.
Spectroscopic observations show that all planetary nebulae are expanding. This led to the idea arose that planetary nebulae were caused by a star's outer layers being thrown into space at the end of its life.