The Universe
The Universe is the container for absolutely everything we know. The Hubble telescope has begun to show us how large the universe is.
We are in the Milky Way galaxy. It is just one of an estimated 125 billion galaxies in the Universe. Recent results from the Hubble telescope would indicate that this number is grossly underestimated!!!
It is impossible to understand the size of the Universe. But to make things even more difficult to grasp, let us consider the number of stars in our galaxy alone. Of course we have no way of counting them all. But astronomers are serious when they estimate that there are 200 billion to 400 billion stars contained within the Milky Way.
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Our Sun is a fairly small star but it is still an enormous nuclear fusion reactor. Every second four million tonnes of hydrogen is converted into helium. The temperature on the surface of the Sun is approximately 6000oC.
Despite our Sun being a fairly small star and burning four million tonnes of hydrogen per second, it is estimated that the Sun will take 7 billion years to use up all the hydrogen!
So you can begin to imagine what the estimated 200 billion to 400 billion stars contained within our galaxy alone are generating in heat and light. Now multiply this by the othere 125 billion galaxies in our Universe.
Our Solar System
The Solar System consists of a star, which we call the Sun, and eight planetary bodies. We are on the third planet from the Sun.
The planets we call Mercury and Venus have an orbit around the Sun that is within the orbit of planet Earth around the Sun. There are four other planets, Jupiter, Saturn, Uranus and Neptune, which have an orbit ouround the Sun which is outside of the orbit of the Earth.
