chro·mo·sphere \ˈ ̷ ̷ ̷ ̷+ˌ-\noun (-s) Etymology:chrom- + sphere : the lower part of the atmosphere of the sun thousands of miles thick and composed predominantly of hydrogen gas that is responsible for its rosy color; also: a similar portion of the atmosphere of any star • chro·mo·spheric\| ̷ ̷ ̷ ̷+\adjective