The Milky Way is not just a beautiful sight in the night sky. It is a giant rotating disc of stars, gas and dust that contains the entire solar system. When you look up on a clear, dark night, the fuzzy, irregular band in the sky is actually the edge-on view of the galactic plane of the Milky Way. It defines our place in the universe.
Spiral scale
We are dealing with numbers that barely make sense. The diameter of this galaxy is about 150,000 light years. This is an amazing distance. There are hundreds of billions of stars in this disk. They are mixed with huge clouds of interstellar gas and dust. This mixture forms a glowing band we see from Earth.
But here’s the problem. We can’t see everything.
Dust is like fog. It blocks the view of many stars deep in the Milky Way. This made it impossible to explore large areas for a long time. Astronomers were blind to the center. Next is infrared astronomy and radio astronomy. These tools punched through the dust. This allows scientists to map previously hidden parts of the Milky Way.
Hidden mass and center point
What we see in the light is only part of the story. The Milky Way contains large amounts of dark matter. This invisible material adds significantly to the galaxy’s mass, but its exact composition is not yet known. Also, its true shape and exact mass are not completely known. The information is incomplete.
At the very core, things get extreme. There is a massive black hole called Sagittarius A*. It anchors the galaxy. But getting clear images of the core requires advanced radio and infrared technology. Without them, the center would have remained a mystery for decades.
Our address in the galaxy
Where does the earth fit into this? We are not the center. We are also not on the outermost edge. The sun is located in one of the spiral arms of the Milky Way galaxy. It is located approximately 27,000 light years from the center of the Milky Way galaxy. This location is far enough to be relatively stable, but close enough to benefit from the galactic environment.
The sun orbits the core. It takes millions of years to complete one revolution. We are still part of a system that is being mapped. Dust can hide secrets. New telescopes will keep peering through. The actual size and mass of the Milky Way is still unknown. we know where we are. We don’t know the full extent of the house we live in.