What objects are included in the Galaxy?

Our star system (spiral galaxy), to which the Sun belongs. The galaxy contains at least 10 v st. 11 stars (with a total mass of 10 at 11 times the mass of the Sun), interstellar matter (gas and dust, the mass of which is a few percent of the mass of all stars), cosmic rays, magnetic fields, radiation (photons). Most stars occupy a lenticular volume with a diameter of about 30 thousand pc, concentrating towards the plane of symmetry of this volume (galactic plane) and towards the center (the so-called flat subsystem of the Galaxy). A smaller part of the stars fills an almost spherical volume with a radius of about 15 thousand pc (the so-called spherical subsystem of the Galaxy), concentrating towards the center (core) of the Galaxy, which is located from the Earth in the direction of the constellation Sagittarius. The Sun is located near the galactic plane at a distance of about 10 thousand pc from the center of the Galaxy. For a terrestrial observer, stars concentrating towards the galactic plane merge into the visible picture of the Milky Way.