What is galaxy ?

A galaxy is a massive system of stars, stellar remnants, interstellar gas, dust, dark matter, and other astronomical objects bound together by gravity. There are billions of galaxies in the universe, each containing billions of stars. The Milky Way is the galaxy in which our solar system is located. Galaxies come in various shapes and sizes, including spiral, elliptical, and irregular.

A galaxy is a massive, gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. Galaxies range in size from dwarf galaxies with only a few hundred thousand stars to giant galaxies with trillions of stars. The Milky Way, our galaxy, is a barred spiral galaxy with a mass of about 1 trillion solar masses and a diameter of about 100,000 light-years. Galaxies are classified into various types based on their morphology, including elliptical, spiral, and irregular galaxies. They can also be classified based on their star formation activity, with star-forming galaxies and quiescent galaxies. Galaxies form through the gravitational collapse of large clouds of gas and dust, and they evolve over time through mergers and interactions with other galaxies.