Kwi-astronomy, imetal yiyo nayiphi na i-element yekhemikhali ongaphandle kwe- hydrogen okanye i-helium. Unobangela woko kukuba ezi elements zimbini (nganye amaxesha kuba yi-lithium) zizo kuphela ezenza umququmblelo wee-nkwenkwezi. Esibhakabhakeni, i-telescope ingazibona iimpawu zee-metals ize ke emva i-astronomer yazi okokuba kukho ii-nkwenkwezi.