When two galaxies collide, their stars almost never actually hit each other.

The Milky Way contains roughly 100 billion to 400 billion stars, yet the distance between them is staggering. On average, stars in our neighborhood are separated by about 5 light-years, which is approximately 30 trillion miles. This immense void means that the probability of two stellar nuclei physically colliding during a galactic merger is nearly zero.Astronomers use the 'mean free path' calculation to determine collision frequency. For stars in a typical galaxy, this path is much larger than the size of the galaxy itself. Even in the dense core of a galaxy, where stars are packed much tighter, the odds of a direct hit remain extremely low. Instead of physical impacts, the primary interaction is gravitational.Gravity acts as a long-range force that strips gas and dust from the colliding systems. This process often triggers a 'starburst' phase, where the compression of interstellar gas clouds leads to a rapid surge in new star formation. The Hubble Space Telescope has captured many examples of this, such as the Antennae Galaxies (NGC 4038 and 4039), which began their collision hundreds of millions of years ago.Our own Milky Way is currently on a collision course with the Andromeda Galaxy, moving at about 68 miles per second. This event is expected to occur in approximately 4.5 billion years. Despite the massive scale of the merger, researchers at institutions like NASA and ESA predict that our Solar System will likely remain intact throughout the entire process.