The Milky Way is a barred spiral galaxy with a diameter of about 100,000-200,000 light-years. It contains between 100-400 billion stars and at least that many planets. The Solar System is located about 27,000 light-years from the Galactic Center, on the inner edge of the Orion Arm.
At the very center of our galaxy lies Sagittarius A*, a supermassive black hole with a mass of about 4 million times that of our Sun. It's surrounded by a dense cluster of stars and gas clouds. The first image of Sagittarius A* was captured by the Event Horizon Telescope and released in 2022.
The inner few hundred light-years of the galaxy contain a dense concentration of molecular gas, with active star formation and numerous massive stars. This region is obscured at visible wavelengths by interstellar dust but can be observed in infrared and radio wavelengths.
Extending above and below the galactic center are two enormous bubbles of high-energy gamma-ray emission, discovered by the Fermi Gamma-ray Space Telescope. These "Fermi Bubbles" extend about 25,000 light-years from the center and may be the result of past activity from the central black hole.
Young, metal-rich stars found primarily in the spiral arms. These include hot, blue O and B stars that illuminate the spiral arms, making them visible. These stars formed relatively recently from gas enriched by previous generations of stars.
Older, metal-poor stars found mainly in the galactic bulge and halo. These stars formed early in the galaxy's history when the interstellar medium contained fewer heavy elements. Globular clusters are collections of these ancient stars.
The space between stars is not empty but filled with gas and dust. Dense regions of this material form dark dust lanes visible along the spiral arms. These dust clouds are the birthplaces of new stars, continuing the cycle of stellar evolution.
Our Solar System is located about 27,000 light-years from the galactic center, in what's called the Orion Arm or Local Spur. This is a relatively minor spiral arm between the larger Perseus and Sagittarius Arms. We're slightly above the galactic plane, in a relatively quiet neighborhood with a moderate density of stars.
The Sun orbits the center of the galaxy at a speed of about 220 km/s (490,000 mph), taking approximately 225-250 million years to complete one orbit. This period is known as a "galactic year." Since the formation of the Solar System about 4.6 billion years ago, we've completed about 20 galactic orbits.