Simply put, the galaxy is the galaxy in which we live, it contains a cluster of over two hundred billion stars including our Sun and indeed our solar system. It is only one of over one hundred billion galaxies in the observable universe. Our solar system is located on one of the six spiral arms of the Milky Way named Orion, if you are somewhere that has a really dark night sky and are far away from artificial light pollution you can see the Milky Way.

It appears as a hazy band of light forming a large arc that spirals across the sky. It is almost as old as the universe itself, the oldest star found being over thirteen billion years old. The name itself, Milky Way, is a translation from the Greek, Galaxis, which is derived from the word milk, derived from the appearance of spilt milk in the sky. Indeed, the Milky Way was first observed by the Greek philosopher Anaxagoras in the fifth century BCE. Proof of the long debated theory that the Milky Way consisted of a cluster of stars came in 1610 by way of Galileo. In 1755, Immanuel Kant correctly speculated that the Milky Way was a rotating body of a huge number of stars held together by gravitational forces similar to the solar system but on a colossal scale.

And it is a colossal scale - the circumference being between two hundred and fifty and three hundred light years! As big as it is, astronomers are confronted with massive problems when trying to observe it, because the Earth is part of the Milky Way, they can't simply look down on it to study it. So, they explore other galaxies and apply what they learn from viewing them onto the Milky Way.



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