Of enormous magnitude; immense: an astronomical increase in the deficit. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "astronomical" in a sentence
"In addition, it took 11 years of observing to tease out the presence of the habitable zone planet, a short time in astronomical terms."
""One hundred million years to a human seems an awful long time, but in astronomical time periods, that's nothing compared to the life of the stars.""
"WASHINGTON & mdash; The cost of NASA's replacement for the Hubble Space Telescope is giving new meaning to the word astronomical, growing another $1.5 billion, according to a new internal NASA study released Wednesday."