Do we know if there is a black hole located in the center of the Milky Way? How far away is Earth's nearest nebula and what is the name of this nebula?   How is a Type I supernova different from a Type II supernova? How long do quasars last? How many galaxies are there in the universe? How do we determine the size and distances of stars? Is there any star isolated and doesn't belong to a galaxy? What is the vernal equinox? What happens when galaxies collide? How many stars are in the Milky Way? How many galaxies are there? How was the solar system formed? What is the missing mass in the universe caused by? Is the expansion of the universe slowing down right now? How big is the Universe? Will better images than the Hubble Deep Field ever show the edge of the universe?   What are the two closest stars to us? What do you know about the giant red star closest to the Earth? How often does a supernova happen in the universe?