Glossary While you were browsing this website, you may have come across a few terms that you did not know. If so, this glossary will be able to tell you the definition of some of the terms, If you have found any words you don't know in this website, and they are not listed below, e-mail us and we will put up the word and its definition. 1) astronomy - A branch of physics that studies celestrial bodies and the whole universe. 2) bulge (noun) - The spherical cloud of stars in the central part of a galaxy. 3) cluster of galaxies (noun) - A large group of galaxies which may contain as many as several thousand large and dwarf galaxies. 4) Cosmos (proper noun) - The entire physical universe which has been seen and recorded. 5) disk (noun) - The flat part of galaxies where there are clouds of interstellar matter and young stars. 6) galaxy (noun) - A large collection of stars, gaseous clouds, and interstellar medium bound together by gravity. First classified by Edwin Hubble. 7) globular star cluster (noun) - Concentration of millions of stars held together by gravity. 8) group of galaxies (noun) - A group of galaxies that contains about ten or more large galaxies, as well as a few dwarf galaxies. 9) interstellar (adjective) - Between or among the stars. 10) lenticular (adjective) - Having to do with lens. 11) morphology (noun) - Description of galaxy structures. 12) Nobel Prize (proper noun) - An annual award for outstanding contributions to chemistry, physics, physiology, medicine, literature, economics, or peace. Started by Alfred Nobel, the inventor of dynamite. 13) observatory (noun) - A building, place, or institution designed for making astronomical or meteorological observations. 14) quasar (noun) - Object which emits strong radio waves. 15) Seyfert galaxies (noun) - Any class of galaxy with active nuclei. These galaxies were named after Carl K. Seyfert, who called them to attention in 1944. 16) spectrum (noun) - Band of colors. 17) spectroscope (noun) - Studies light collected from the sun, a star, or a galaxy. 18) spiral arms (noun) - Wave of gas, stars, and dust which travels through the disk of the spiral galaxy.