Giant molecular cloud

/ˈdʒaɪənt məˈlɛkjələr klaʊd/ noun

Definition

Massive collections of molecular gas and dust that can contain 100,000 to several million solar masses of material and span 50-300 light-years across. These are the largest gravitationally bound structures in the galaxy and the sites of most star formation.

Etymology

The term was coined in the 1970s when radio observations revealed that molecular clouds come in a hierarchy of sizes, with the largest examples being truly gigantic compared to smaller molecular clouds. The 'giant' designation distinguishes these massive star-forming regions from smaller molecular cloud complexes.

Kelly Says

Giant molecular clouds are the skyscrapers of the galaxy - massive, towering structures that dominate the galactic landscape! A single giant molecular cloud contains enough material to build entire star clusters and associations. These cosmic giants are constantly being stirred by stellar winds, supernova shockwaves, and galactic rotation, creating a dynamic environment where stars are born in waves across millions of years.

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