What holds a galaxy together?

What holds a galaxy together?

Our galaxy, the Milky Way, is typical: it has hundreds of billions of stars, enough gas and dust to make billions more stars, and at least ten times as much dark matter as all the stars and gas put together. And it’s all held together by gravity.

What defines a galaxy?

Galaxies are sprawling systems of dust, gas, dark matter, and anywhere from a million to a trillion stars that are held together by gravity. Nearly all large galaxies are thought to also contain supermassive black holes at their centers.

What is the name of a ball of glowing hot gases in the sky?

A star is a huge glowing ball of hot gas, mainly hydrogen and helium. The temperature is so high in its core that nuclear fusion occurs, producing energy.

How was Sun formed?

The Sun and the planets formed together, 4.6 billion years ago, from a cloud of gas and dust called the solar nebula. A shock wave from a nearby supernova explosion probably initiated the collapse of the solar nebula. The Sun formed in the center, and the planets formed in a thin disk orbiting around it.

What is the source of gravity that holds our galaxy together?

What holds galaxies together? Gravity. All of the stars of a galaxy are all attracted to each other. This attraction is weak because the stars are very far apart, but it is enough to keep the galaxies together.

What are the 4 components of a galaxy?

This structure can be viewed as consisting of six separate parts: (1) a nucleus, (2) a central bulge, (3) a disk (both a thin and a thick disk), (4) spiral arms, (5) a spherical component, and (6) a massive halo. Some of these components blend into each other.

What is a giant ball of glowing gas that is very hot?

Overview: A star is a huge luminous ball of hot gas, mostly hydrogen and helium, held together by gravity. Nuclear reactions in the cores of all stars, including our Sun, produce energy in the form of light. Stars shine because this light works its way to the surface and radiates out into space.