Very briefly, you will journey in the direction of the constellation Sagittarius for 27,500 light years. Enroute, you will pass through the interarm 'gap' between where our solar system lives in the Orion Spur, and the Sagittarius spiral arm with its bright nebulae and star forming clouds. Most of the light from the stars in the center of the Milky Way will continue to be obscured by interstellar clouds until you pass through yet another Inter Arm Gap some 6,000 light years wide, and arrive at the 'Inner Arm' located about 9,000 light years from the center. Not much is known about this spiral arm. Passing through this arm you arrive within the inner kiloparsec zone some 3,000 light years in diameter. The stars, here, suddenly begin to blaze into view and what you see is very much like a gigantic globular cluster containing several billions of stars and apparently not a whole lot of interstellar clouds.
As you approach the inner 300 parsec zone, the density of stars continues to rise very sharply as you enter the core region, and you now enter a rapidly rotating disk that is suddenly rich in molecular clouds. It comes upon you seemingly out of nowhere. This disk is very lumpy and consists of many independent interstellar clouds, the largest is called Sagittarius B2 which contains millions of times the mass of the Sun, and many very active star forming sites. This is the first such nursery you have seen since leaving the 3-kiloparsec arm. As you journey trough this disk, you arrive at its inner edge located about 150 light years from the Galactic Center. This is a zone in which individual clouds cannot exist as cohesive entities against the gravitational tidal forces of the central star cluster containing 10s of millions of stars. This is not the end of the journey, however.
Within 10 light years of the center, we come upon a second rotating disk of gas, existing within a nearly spherical swarm of several million stars, including a dozen red supergiants on the verge of becoming supernovae. This disk rotates at over 100 kilometers per second, and far faster near its center. Within a few light years of the center we gas being stripped from the inner edge of this disk and falling along two arms into the deeper regions where we find the remains of a recent supernova nebula expanding, and a knot of infrared and radio radiation that comes from a source called Sagittarius A* ( 'A star '). Sag A* has been studied for decades and seems to be a million- solar-mass black hole with its own orbiting disk of gas, slowly being drawn into the hole, producing the energy we now see. The environment of this inner zone must be very strange. Thousands of normal, but very old stars are crowded together into a region only a few light years across, and the night sky must glow with a faint but ever-present light from the gas and stars. The sky is pierced by the light from dozens of red super giants, and every few million years, one of them erupts as a supernova ejecting enormous quantities of luminous matter into the crowded interstellar space. Such occasional explosions may also disrupt the flow of gas into the center and destroy the rotating disks of gas, which only re-establish themselves later on once things have quieted down.