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.
X-Ray Visible Light Mid-Infrared Far-Infrared Radio Waves. Ultraviolet Light Visible Light Near-Infrared Radio Waves. Messier 81 (above) is a spiral galaxy. In X-rays we see the bright central core of this galaxy as well as a distant quasar, which appears as a bright knot directly below the galaxy's center. Ultraviolet reveals hot, young stars and multiple spiral.