If our sun suddenly disappeared from our solar system, all of our planets would travel in a straight line, because the sun keeps us rotating in a circle. Earth wouldn't be able to see the moon since the way we see the moon is because of the suns rays reflection. The temperature would drop even through the seasons. If we had no sun, no life would cease to exist on Earth, since Earth has the perfect positioning to have life on Earth. So without any sun, there wouldn't be any life whatsoever.
The way we got all the names for our planets was from Roman and Greek gods and goddesses. Yet Earth was named after a German and English name. But out of all of the planets, Jupiter's name comes from The King of the Roman gods. Neptune was the Roman God of the Sea, Mars was the Roman God of War, and Mercury was the Roman God of Travel.
In 1 Billion Years, the Earth will not look the same because of the Suns Luminosity, and all the liquid oceans will evaporate. In 2.8 billion years, the earths surface will then be 300 degrees F, which means all the organisms on Earth will all be dead, in 7.59 billion years, the sun today will change dramatically to 256x larger than itself. But then, in 8 billion years, the sun will return to a dwarf star, and every planet will plummet to very low temperatures, and every living thing will most likely die. But then in 450 billion years, all the galaxies will then merge into one, in 12 trillion years, the very last star will then die out, but then new ones will be reborn. But soon in 120 trillion years, all the stars in our universe will soon all die out, all dwarfs will smash and collide.
Both of the Black Holes combine, they would combine by moving inward by gravitational waves, soon once they collide, will create a ripple in space. This is a very loud noise yet we do not hear since it is light years away from our planet. Also when combining 2 black holes, you get a larger one.
If 2 galaxies collided, the dust and gas, those materials would interact . The materials will react gravitationally, there's also friction between the gas in the colliding galaxies, this will trigger stars to go into a formation. Once both of the galaxies combine, it will become a larger galaxy merging together.