There are about 80-100 billion galaxies in the observable universe, that is, that part of the universe visible to us. There may be more in that part of the Universe beyond our observable limit, which occurs about 400,000 years after the Big Bang. Before that time, the universe remains opaque to us. It's like trying to see through a dense fog. After this time, the "fog" lifted and light could traverse the universe. This occurred because the universe expanded and cooled, allowing electrons to pair with protons and light to travel without bumping into the free electrons.

The mind blowing thing to think about is all the stars in these galaxies... Our Milky Way has roughly 200 billion stars. While we've discovered over 300 planets outside our Solar System, the galaxy must be filled with trillions of planets. Now think about each of those 100 billion galaxies in our observable universe. Each has hundreds of billions of stars and probably trillions of planets too. Do any of them harbor life? We do not know, and we may never know. But we continue to look.

Yes, the Sun, and all the planets of the Solar System, are all part of the Milky Way galaxy. The Sun is but one of 200 billion stars in the Milky Way. Most of these are not visible in the night sky. In fact, only about 9,000 nearby stars are visible to the unaided eye.

We exist in the outer parts of the galaxy, in the "galactic suburbs," as it were. We're about 26,000 light-years from the center of the Galaxy. We revolve around the Galaxy about once every 225 billion years. Since the Sun formed 5 billion years ago, we have made about 22 revolutions around the Galaxy. Since the dawn of human origins, the Sun has only revolved 1/1250th of its orbit around the Galaxy.

The other side of the Milky Way is basically the same as the neighborhood here near the Sun: there are stars, gas and dust, making up spiral arms within the galactic disk. It’s hard for us to see through all the dust and confusion of the center of the Milky Way, but we have some knowledge of things there on the Sun’s orbit, or what we call the Solar circle. For example, some of the links here discuss the recent discovery of a previously unknown (but suspected) spiral arm on the other side of the Galaxy.