Milky Way

The definition of the Milky Way is a galaxy 100,000 light years in diameter, 25,000 light years from its center and 1,000 light years thick.

Size of the Milky Way Galaxy

• The Milky Way is a bar-shaped structure composed of over 400 billion stars.
• The closest large spiral galaxy to the Milky Way is the Andromeda galaxy, which is larger at 220,000 light years across. It is 2.7 million light years away.
• A galaxy partially inside the Milky Way is Canis Major which is just 42,000 light years from the center of the Milky Way.
• The Milky Way galaxy contains 200 to 400 billion stars.
• The center of the Milky Way galaxy is approximately 26,000 light years from the Sun.
• All the stars which are visible from Earth are in the Milky Way galaxy.
• When looking at it in the night sky, the center of the Milky Way galaxy is in the Sagittarius constellation.
• The dark areas in the Milky Way galaxy are dark nebulae, which block the light from distant stars.

More Facts About the Milky Way

• The Milky Way galaxy was named from the Greek word for "milk." In mythology, the goddess Hera was nursing her son Hercules, and some of the milk was spilled.
• The Milky Way galaxy is spiral in shape with a bar-shaped center area. Ninety percent of its mass is dark matter and the rest is gas, dust, and stars. It has a very massive black hole at its center. It is moving through space at 630 km per second.
• Its estimated age is around 13.6 billion years, which puts it almost as old as the Universe. The disk and the bulge in the center probably formed about 10 to 12 billion years ago.
• The Milky Way galaxy is part of a group of galaxies called the Virgo Supercluster. The closest neighbors are the Large and Small Magellanic Clouds and the Andromeda galaxy.
• The four main arms of the Milky Way galaxy are named the Carina and Sagittarius arm, the Perseus Arm, the Norma and Cygnus Arm, and the Scutum-Crux Arm. The Orion arm, where Earth is located, is one of the smaller arms.
• The Milky Way galaxy is 100,000 light years in diameter.