The Little Ghost
Nebula is a planetary nebula that was discovered by 18th-century
astronomer William Herschel as he used a telescope to explore the
constellation Ophiuchus.
Round and planet-shaped, the
nebula is also relatively faint and has acquired the popular
moniker of Little Ghost Nebula. Planetary nebulae in general are
not at all related to planets, but instead are created at the end
of a sun-like star's life as its outer layers expand into space
while the star's core shrinks to become a white dwarf. The
transformed white dwarf star, near the center, radiates strongly at
ultraviolet wavelengths and powers the expanding nebula's
glow.
The nebula's main ring structure
is about a light-year across and the glow from ionized oxygen,
hydrogen, and nitrogen atoms are colored blue, green, and red
respectively. Over 2,000 light-years away, the Little Ghost Nebula
offers a glimpse of the fate of our Sun, which should produce its
own planetary nebula only about 5 billion years from
now.
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Little
Ghost Nebula on date 18 March 2009.