Definition of planetary nebula in English:

planetary nebula

Line breaks: planet|ary neb¦ula

noun

Astronomy
  • A ring-shaped nebula formed by an expanding shell of gas round an ageing star.
    More example sentences
    • Astronomers call such an object a planetary nebula, because its round shape resembles that of a planet when viewed with a small telescope.
    • The Boomerang Nebula is a young planetary nebula and the coldest object found in the Universe so far.
    • Until recently, it was thought that shells around planetary nebulae were a rare phenomenon.

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Word of the day maelstrom
Pronunciation: ˈmeɪlstrəm
noun
a powerful whirlpool in the sea