Composite picture of the Cat's Eye Nebula (NGC 6543), combining three images taken by the any of a class of bright nebulae that may somewhat resemble planets when viewed through a small telescope but are in fact expanding shells of luminous gas far outside the solar system. See nebula.
PLANETARY NEBULA
Meaning of PLANETARY NEBULA in English
Britannica English vocabulary. Английский словарь Британика. 2012