Galaxies

Galaxy is a huge mass of stars communicable and interstellar material. The smallest galaxies contain about 100000 stars, while the largest container up to 3000 billion stars. There are three main types of galaxies classified according to their shape; elliptical which are oval shaped; spiral coma which have arms spiralling out words from a central bulge (those whose aam spiral from bar shaped bulge are called spirals); and irregular, which have no of their shape. Sometimes the shape of a Galaxy is distorted by a collision with another galaxy. Quasars (quasisteller objects) are thought to be Galaxy nuclear but are so far away that their exact nature is still uncertain. They are a highly luminous objects in the outer reaches of the known universe while the furthest known “ordinary” galaxies are about 12 billion light years away the furthest known quasar is about 13 billion light years away. Active galaxies, such as Seyfert galaxies and radio galaxies emit intense radiation. In a Seyfert galaxy, this radiation comes from the galactic nucleus; in a radio galaxy , it also comes from huge lobes other side of the Galaxy. The radiation from active galaxies and quasars is thought to be caused by material falling into central black holes.