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.
These twisted galaxies range from a billion to a trillion times as massive as the sun. The visible disk can be anywhere from 10 to 300 thousand light-years across. The largest known spiral galaxy is NGC 6872, which is 522,000 light-years across from the tips of its outstretched spiral arms, about 5 times the size of the Milky Way. In the early universe, galaxies frequently collided and interacted with one another, so the spiral shape of these ancient giants would have been quickly disrupted.