galactic coordinate system
Save This Word!
The coordinate system in which a celestial object's position on the celestial sphere is described in relation to the structure of the Milky Way galaxy.♦ An object's galactic longitude is measured along the galactic equator, a great circle on the celestial sphere that follows the band of the Milky Way. The galactic equator, also called the galactic circle, is inclined at an angle of approximately 62° to the celestial equator; distances are measured along it beginning at a point in the constellation Sagittarius lying in the direction of the Milky Way's nucleus. The galactic poles are the two points where a perpendicular line through the middle of the plane of the galactic equator intersect the celestial sphere.♦ An object's galactic latitude is measured in degrees north or south of the galactic equator toward the galactic poles.
QUIZZES
QUIZ YOURSELF ON PARENTHESES AND BRACKETS APLENTY!
Set some time apart to test your bracket symbol knowledge, and see if you can keep your parentheses, squares, curlies, and angles all straight!
Question 1 of 7
Let’s start with some etymology: What are the origins of the typographical word “bracket”?
First appeared around 1750, and is related to the French word “braguette” for the name of codpiece armor.
First appeared in 1610, based on the French word “baguette” for the long loaf of bread.
First appeared in 1555, and is related to the French word “raquette” for a netted bat.
TAKE THE QUIZ TO FIND OUT 
Meet Grammar Coach
Improve Your Writing
Words nearby galactic coordinate system
galactagogue, galactan, galactic, galactic cluster, galactic coordinate, galactic coordinate system, galactic equator, galactic halo, galactic latitude, galactic longitude, galactic nebula
The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.