Why does the moon lack an atmosphere?
How does a black hole form?
Why aren't you googling your questions??
https://www.google.com/search?q=Why+does+the+moon+lack+an+atmosphere%3F&oq=Why+does+the+moon+lack+an+atmosphere%3F&aqs=chrome..69i57j69i61.1576j0j7&sourceid=chrome&ie=UTF-8
https://www.google.com/search?q=how+does+a+black+hole+form%3F&oq=how+does+a+black+hole+form%3F&aqs=chrome..69i57j69i64.7101j0j7&sourceid=chrome&ie=UTF-8
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