Jeff Stanger introduction to Astronomy

Astronomy Rocks!

Astronomy is the oldest science, it deals with the biggest ideas and it is Australia's most productive science. It's no wonder then that you are here to check out these pages. Astronomy has a universal appeal at some level to everyone and I hope I can help you find what you are looking for. First I'll mess with your head (Mwahaha) and hopefully correct any common misconceptions about our place in space.

Your place in Space

Few people really appreciate how ridiculously small insignificant we really are. Our whole planet is just a small speck orbiting a star that is just one of the hundreds of billions of stars that makes up the Milky Way (our Galaxy). As if that wasn't bad enough the Milky Way is only one of hundreds of billions of galaxies in the Universe. So basically the world that consumes your attention and thoughts every day is actually just an insignificant spec in terms of the vast and eternal Universe.

One way to think about the numbers of stars and galaxies in the Universe is as follows:

Think of an Olympic sized swimming pool. Fill that swimming pool with 1mm grains of sand. That would be about 200 billion sand grains. Each one of those grains of sand would represent a star in our Milky Way. So just imagine if you wanted to find our Sun you would need to find one single sand grain in that swimming pool :P. We now think that possibly half of the stars in the Milky Way have planets around them. So even if the possibility of life somewhere else in our galaxy is very small there is still a good chance we are not alone.

Now using our swimming pool analogy again those grains of sand could also approximately represent the number of galaxies thought to be in the entire Universe. So there are 200 billion stars in a typical galaxy and there are about 200 billion galaxies. The odds for life else ware in the Universe are getting even better. So another way to think about all these galaxies full of stars is that there are more stars in the Universe than there are grains of sand on the whole Earth. Think about that for a minute and you'll realise how incomprehensibly big the Universe must be. More stars than the sand grains in every beach and every dune you have ever seen or walked on. Wow ... my head hurts :).

It's mostly empty Space and so are you!

Let's get one thing straight. The Sun is a star just like all the ones you see in the night sky. The thing that makes it different is that it is close to us. That is if you call 150 million km close? At 100km/hr it would take you about 170 years to get there. So the stars in the night sky don't look like the Sun because they are very far away. How far? Well the closest star to the Sun is about 4.3 light years away. That's about 40 trillion km or 271000 times further than the Sun. Another was to think about that is that it would take the space shuttle about 170000 years to get there or about 46 million years at 100km/hr.

So you can see that the distance to our Sun's next door neighbour is vast and that is a pretty typical interstellar distance in our galaxy. So that brings me to my first point, Space is mostly empty. Another consequence of this is that even if we are not alone in the universe we are probably jut too far away to ever meet anyone else.

The other thing to realise is that there is just as much empty space inside you as there is between the stars. An atom is more than 99% empty space where electrons whiz around the nucleus. If an atom was the size of a football field the nucleus would be about 1cm across in the middle and there would be a cloud of electrons buzzing around all over the field. You are made of billions and billions of atoms but they are mostly empty space so here we have it, even you are mostly empty space.

Science exposes the universe around you

So now you can see that our scientific understanding puts a whole new perspective on our everyday lives. If you are ever bored take the time to contemplate the almost infinite scale of the universe, our place in it and the multitude of unseen things that are going on around and within you. You will never view your world the same again.