The Milky Way is the galaxy that contains our Solar System. It is a barred spiral galaxy, a massive collection of stars, dust, and gas bound together by gravity. From our perspective within one of its spiral arms, the Milky Way appears as a band of light in the night sky.

Structure and Size

The Milky Way has a diameter of about 100,000 to 180,000 light-years and is thought to contain 100 to 400 billion stars.

Main Components

The galaxy consists of several distinct components:

• Galactic Center (Bulge): A central, tightly packed group of stars. At its very heart lies a supermassive black hole, Sagittarius A*, with a mass about four million times that of the Sun.
• Disc: This is where the majority of the galaxy's stars, gas, and dust are located, arranged in spiral arms. Our Solar System resides in the Orion Arm.
• Halo: A large, spherical region surrounding the disc and bulge, containing globular clusters and dark matter.

Our Place in the Galaxy

Our Solar System is located about 27,000 light-years from the Galactic Center, situated in the Orion Arm (sometimes considered a minor spur of the Perseus Arm). The Sun orbits the Galactic Center, taking roughly 240 million years to complete one revolution.

The Galactic Black Hole

At the center of the Milky Way is Sagittarius A* (Sgr A*), the supermassive black hole. While we cannot directly see the black hole itself, its presence is inferred by the orbits of stars and gas near the center of the galaxy.

Observing the Milky Way

Observing the Milky Way is best done under dark skies, away from light pollution.

Future of the Milky Way

The Milky Way is currently on a collision course with the Andromeda Galaxy (M31). This cosmic event is expected to occur in about 4.5 billion years, eventually leading to the formation of a new, larger elliptical galaxy, often nicknamed "Milkomeda."