Universe (Galaxy)

What is a galaxy?

 Galaxy

Galaxies are large groups of stars. A single galaxy contains millions or billions of stars & can be as large as 200,000 light-years across.  Galaxies consist of dust & gats, which are bound together by a strong force of gravitation.

A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek galaxy, literally "milky", a reference to the Milky Way. Galaxies range in size from dwarfs with just a few hundred million (108) stars to giants with one hundred trillion (1014) stars, each orbiting its galaxy's center of mass.

Galaxies are categorized according to their visual morphology as elliptical, spiral, or irregular. Many galaxies are thought to have supermassive black holes at their centers. The Milky Way's central black hole, known as Sagittarius A*, has a mass four million times greater than the Sun. As of March 2016, GN-z11 is the oldest and most distant observed galaxy with a comoving distance of 32 billion light-years from Earth and observed as it existed just 400 million years after the Big Bang.

NGC 4414, a typical spiral galaxy in the constellation Coma Berenices, is about 55,000 light-years in diameter and approximately 60 million light-years from Earth.

Point:- It is believed that the universe contains more than 100 billion galaxies.

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