1.A galaxy is a collection of planets of stars and space. The name of our galaxy is the “milky way”, and its shape is of a spiral. 2.Another galaxy found in space is called “Andromeda”. 3.There are millions upon millions of galaxies in the universe. 4.Cosmology is the study of the cosmos.
5.Light Year: The distance that light travels in a vacuum in one year, approximately 9.46 trillion (9.46 × 1012) kilometers or 5.88 trillion (5.88 × 1012) miles. Star: A self-luminous celestial body consisting of a mass of gas held together by its own gravity in which the energy generated by nuclear reactions in the interior is balanced by the outflow of energy to the surface, and the inward-directed gravitational forces are balanced by the outward-directed gas and radiation pressures. Nova: A star that suddenly becomes much brighter and then gradually returns to its original brightness over a period of weeks to years. Supernova: A rare celestial phenomenon involving the explosion of most of the material in a star, resulting in an extremely bright, short-lived object that emits vast amounts of energy. Nebula: A diffuse mass of interstellar dust or gas or both, visible as luminous patches or areas of darkness depending on the way the mass absorbs or reflects incident radiation. Pulsar: Any of several celestial radio sources emitting short intense bursts of radio waves, x-rays, or visible electromagnetic radiation at regular intervals, generally believed to be rotating neutron stars. Quasar: An extremely distant, and thus old, celestial object whose power output is several thousand times that of our entire galaxy. Black Hole: An area of space-time with a gravitational field so intense that its escape velocity is equal to or exceeds the speed of light.