Thrilled, delighted, as in Dean's in orbit over his son's success. This expression alludes to the successful launching into orbit of a satellite or other spacecraft. [Slang; late 1900s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.