The Milky Way Galaxy is the galaxy in which our solar system is located. In fact, we are already within the Milky Way Galaxy. So, if you were to "enter" the Milky Way Galaxy, it would essentially mean moving within the galaxy itself rather than moving from outside to inside.
Within the Milky Way Galaxy, you would encounter various components, including stars, planets, asteroids, comets, dust, gas, and other celestial objects. The galaxy is a vast collection of billions of stars, along with their associated planetary systems. As you move through the Milky Way, you would pass through different regions with varying densities of stars and interstellar matter.
Keep in mind that the distances within the galaxy are enormous, and traveling from one star system to another would require significant time and resources using our current technology. The Milky Way has a diameter of approximately 100,000 light-years, and our solar system is located about 27,000 light-years away from the galactic center. So, "entering" the Milky Way would involve navigating through its various regions, encountering different star systems, and experiencing the diverse environments present within the galaxy.
Exploring the Milky Way Galaxy is a subject of ongoing scientific research and interest. There are many exciting phenomena to study and discover within the galaxy, such as star clusters, nebulae, black holes, and potentially habitable exoplanets.