No one knows the exact size of the Universe, because we cannot see the edge – if there is one. All we do know is that the visible Universe is at least 93 billion light years across.
Our solar system is located in the outer reaches of the Milky Way Galaxy, which is a spiral galaxy. The Milky Way Galaxy contains roughly 200 billion stars. Most of these stars are not visible from Earth.
A stellar nebula (a star) is a very hot ball of gas that eventually dies after 6 stages, the first stage of its life is quite small it starts to grow and get hotter it turns bright yellow and then bright red, it then looses all of its energy and starts to shrink it then has no energy left so it disappears
Most astronomers believe the Universe began in a Big Bang about 14 billion years ago. At that time, the entire Universe was inside a bubble that was thousands of times smaller than a pinhead. It was hotter and denser than anything we can imagine. Then it suddenly exploded. The Universe that we know was born.