a galexy
Gravity and inertia are the two forces that act on all matter in the universe. If there were only two stars in the universe and they were standing still, the force of gravity would cause them to eventually fall together and collide. But there are hundreds of billions of stars in the Milky Way alone, and billions of other galaxies out there, and NOTHING is standing still; everything is in motion. The primary forces that keep the stars from falling together is the rotation of the Milky Way; all the stars appear to orbit the center of the Milky Way.
Galaxy
The answer is simple: gravity.
Their own gravity keeps them together.
Yes, stars are born when gravity pulls gas and dust together from a nebula.
A system of billions of stars held together by gravity is called a galaxy. The one we live in is called the Milky Way galaxy.
a cluster
An island comprising billions of stars and nebulae, held together by gravity.
Galaxy
That is a galaxy.
A galactic cluster is a collection of hundreds or even thousands of galaxies which are bound together by their gravity, each one containing billions of stars. The mass of a galactic cluster could be a quadrillion times the mass of the sun.
Gravity and inertia are the two forces that act on all matter in the universe. If there were only two stars in the universe and they were standing still, the force of gravity would cause them to eventually fall together and collide. But there are hundreds of billions of stars in the Milky Way alone, and billions of other galaxies out there, and NOTHING is standing still; everything is in motion. The primary forces that keep the stars from falling together is the rotation of the Milky Way; all the stars appear to orbit the center of the Milky Way.
The collection of all visible or detectable galaxies is known as the universe. Each galaxy is a vast collection of stars--billions of them. Some galaxies have trillions of stars.
it is a galaxy.
It is a galaxy.
That sounds like a galaxy. It could also be a galaxy cluster or a supercluster.
Galaxy