When two spiral galaxies merge, what component interacts directly and causes significant visible effects?

Answer

The vast clouds of interstellar gas and dust

Because galaxies are mostly empty space, direct star-on-star impacts are rare during mergers. The dramatic visible effects stem from the immense clouds of gas and dust slamming into each other.

When two spiral galaxies merge, what component interacts directly and causes significant visible effects?

#Videos

What If The Largest Objects In The Universe Collided? - YouTube

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