Definition of thanksgiving for English Language Learners. Thanksgiving : the fourth Thursday in November in the U.S. or the second Monday in October in Canada celebrated as a legal holiday for people to be thankful for what they have.
A galaxy contains stars, gas and dust. In a spiral galaxy like the Milky Way, the stars, gas, and dust are organized into a bulge, a disk containing spiral arms, and a halo.. Elliptical galaxies have a bulge-like central region and a halo, but do not have a disk.
The Cartwheel Galaxy is one of the most dramatic examples of the small class of ring galaxies, and it is an unusual opportunity to study new stars, because many stars would ordinarily take much longer to form.