The billions of stars that make up our own Milky Way galaxy.
A galaxy is a large collection of stars that are bound to each other by gravitational attraction. Our own galaxy is called the “Milky Way.” It contains about 200-400 billion stars. Most of them are arranged in spiral arms. Together with the Sun and the Solar System, we sit in the Orion spur. What we see in the night sky as a milky band is actually the next closest spiral arm. From that you can imagine the disk shape of the galaxy. In its center, there is a massive black hole that is 4 million times the mass of the Sun.
Caption: Artist's rendering of the structure and shape of the Milky Way galaxy and its spiral arms. This is what it would look like if we could see the Milky from a distance, like we can see other galaxies from Earth. In the Orion spur, we are located about two-thirds of the way out from the center region. Credits: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)
The milky band in the night sky, the namesake of the “Milky Way”. It is particularly bright and beautiful in the Southern hemisphere, as the next inner spiral arm is backlit by the bright, concentrated galactic center region. Credit: Anna Frebel