Milky Way

The Milky Way is our galaxy. Our solar system is a part of the collection of billions of stars held together by gravity. Scientists believe there is a supermassive black hole at the center.

The Milky Way is the galaxy we call home. A galaxy is a collection of dust, gas, and stars held together by gravity. The Milky Way contains hundreds of billions of stars. It is a spiral galaxy, and if we ever left it to see all of it, we would see a bright central bulge, surrounded by spiral arms. There is nothing particularly significant about the Milky Way apart from the fact it is the only galaxy in Universe which we know has life. Our planet and solar system lie in the outer edge of a spiral arm.

The Milky Way was named such because of its appearance from Earth. The milkiness comes from a band of stars that can be viewed in the night sky, although cannot be distinguished when seen with the naked eye. We have never seen our galaxy looking from outside of it so all of our knowledge about the galaxy has come from observations made inside of it.

The center of the Milky Way is about 25,000 light years from our Sun. The Milky Way is not stationary, the spiral arms and the stars that make them up orbit the center of the galaxy at a high speed.Scientists believe there is a supermassive black hole at the center providing the gravitational force which keeps the stars in orbit around it. Around the spiral arms and the center of the galaxy, our Milky Way is surrounded by a sphere-shaped halo made of old stars and globular clusters.

The Milky Way’s nearest galaxy is called Andromeda. Andromeda and the Milky Way are in what is known as a binary system which forms a larger group of galaxies known as the local group.

Milky Way Facts

• Size (Diameter): 100,000 light years
• Estimated total mass: 700 billion solar masses
• Oldest Star: 13.7 billion years old
• Number of Stars: 100-400 billion