Gravity.
To be specific, not only the gravity of all the objects inside the galaxy, but what's in the center:
Evidence points to there being at the center of all galaxies a supermassive black hole.
Supermassive as in larger than the largest star yet compact as if the entire Earth was compressed into a ball smaller than a marble. Thinking of this, you may just begin to see how supermassive they are.
It's pretty mind boggling. However, I'd suggest you continue your research, as I'm not the most reliable source. =P
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.
An island comprising billions of stars and nebulae, held together by gravity.
A group of stars, gas, and dust held together by gravity is known as a galaxy. Galaxies come in various shapes and sizes and can contain billions to trillions of stars. Our own galaxy, the Milky Way, is a spiral galaxy containing around 100-400 billion stars. The gravitational forces within a galaxy keep its components bound together in a cohesive structure.
Item: galaxy. The other items are celestial bodies within a galaxy, while a galaxy is a collection of stars, dust, and gas held together by gravity.
The collection of stars held together by the force of gravity is called a galaxy. Galaxies can vary in size and shape, and they contain not only stars but also gas, dust, and dark matter. Our own galaxy is known as the Milky Way.
Gravity holds a galaxy together.
Exactly, that is what a galaxy is.
That is a galaxy.
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.
It is a galaxy.
it is a galaxy.
A galaxy is a single vast interstellar region held together by a huge gravitational field.
A star and a galaxy are two distinct astronomical entities. A star is a luminous sphere of plasma held together by gravity, while a galaxy is a large system of stars, gas, and dust held together by gravity.
A galaxy.
Galaxy
An island comprising billions of stars and nebulae, held together by gravity.
A group of stars, gas, and dust held together by gravity is known as a galaxy. Galaxies come in various shapes and sizes and can contain billions to trillions of stars. Our own galaxy, the Milky Way, is a spiral galaxy containing around 100-400 billion stars. The gravitational forces within a galaxy keep its components bound together in a cohesive structure.