哈勃拍摄到被朦胧光环环绕的彩色行星星云
NGC 2438 is a planetary nebula, formed after the death of a Sun-like star. The medium-sized star would have expelled its outer layers of gas into space as it died, leaving behind a white-dwarf core. A halo of glowing gas over 4.5 light-years across surrounds the nebula’s brighter inner ring. Many round or nearly round planetary nebulae display these ha...