Everything that exists around us, which is made up of space, time and matter is called Universe. It consists of billions of galaxies, giant red hot stars with some very little stars like our own Sun, some dwarf cool little stars and planets, satellites, asteroids, meteorites, dark matter, dark energy and highly mysterious black-holes. All these things exist in very uncertain boundaries.
What lies beyond these boundaries or where do these boundaries ends, no one can be very sure. The universe is very changeable, it has been expanding since its beginning. What really exist out there in the universe and what are the matter, it made of is still a mystery to the scientists as they don’t have any concrete evidence and theory to explain the mystery of dark matter and dark energy.
3: The Universe