Because the forces that are supposed to drive off mass from dying stars are spherically symmetrical, astronomers before the 1980s thought of planetary nebulae as expanding spherical bubbles [see “Planetary Nebulae,” by Martha and William Liller; Scientifi
Because the forces that are supposed to drive off mass from dying stars are spherically symmetrical, astronomers before the 1980s thought of planetary nebulae as expanding spherical bubbles [see “Planetary Nebulae,” by Martha and William Liller; Scientifi
由于原本认为，从垂死恒星表面将质量载运出来的作用力具有球状对称性，1980年代以前的天文学家，把行星状星云想像成膨胀的球形泡泡（请参见延伸阅读1）。