Sir William Huggins , KCB , OM , FRS , ( 7 February 1824 -- 12 May 1910 ) was an English astronomer best known for his work in astronomical spectroscopy . Sir William Huggins , KCB , OM , FRS ( 7 February 1824 -- 12 May 1910 ) was an English amateur astronomer best known for his pioneering work in astronomical spectroscopy .