giant molecular cloud


A cloud of molecular hydrogen typically located in the arm of a spiral galaxy, believed to be an area of active star formation. Protostars are located in the densest regions of such clouds. See more at protostar.

QUIZZES

THINK YOU’VE GOT A HANDLE ON THIS US STATE NICKNAME QUIZ?

Did you ever collect all those state quarters? Put them to good use on this quiz about curious state monikers and the facts around them.
Question 1 of 8
Mississippi’s nickname comes from the magnificent trees that grow there. What is it?
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.