Ask the Astronomer
Question about colliding galaxies
If galaxies have black holes and two such galaxies were colliding, would the two colliding galaxies form one giant black hole?
This is an interesting question from several physics perspectives. With the discovery of the Hubble Constant, astrophysics tells us that all galaxies are receding or moving away from each other. At the same time we know that locally this is often not true. For example, the Milky Way Galaxy will collide with the Andromeda Galaxy in 5 billion years. In fact there are an number of interacting galaxies that we can observe from Earth that are colliding with each other.
If everything is expanding from everything else how can this be true? It has to do with the uneven distribution of matter in the universe. If we take the ordinary rubber balloon and using black marker pen to place black dots on the surface of that balloon, as we inflate the balloon every dot can be seen to be moving away from every other.
When we take satellites outside the Earth's atmosphere and map the distribution of matter in our universe we see that it is un-evenly distributed. These giant maps that stretch billions of light years demonstrate that the universe is actually clusters and superclusters of clumps of matter. These clumps form clusters of gravity wells that cause both large bodies and small bodies to be attracted to each other. In other words, the same gravitational field that holds the planets around the sun also causes galaxies to be attracted to each other and in some cases -- collide.
A black hole is a point in space whose gravity is so concentrated that not even light can escape. Obviously, this means that astronomers cannot see a black hole. But now powerful telescopes can prove the evidence of them. The Hubble Telescope and other powerful telescopes have detected vast plumes or jets emitted along the polar axis of black holes in the center of galaxies and quasi-stellar objects. We also know that after a large star collapses and forms a supernova that a small black hole can form in its core. Supernovae so approximate the first few nano seconds of the birth of our entire universe that there is a whole section of astronomy dedicated to the discovery and study of supernovae. This is why we at Windowpane Observatory are conducting the name a galaxy program, which allows astronomy enthusiasts to creatively contribute to research into supernovae, as well as search for earth-bound asteroids.