It definitely sounds llike something fictional from an episode of Star Trek but the Oort cloud is a very real phenomenon. It actually consists of a huge number of ice like objects which extend far beyond the orbit of Neptune and even the Kuiper belt. No one is quite sure how big the Oort cloud is but some estimates have suggested that it may be over 50,000 astronomical units long (in real distance that’s about 4.6 trillion miles). It’s end marks the very edge of the Solar System.
In fact the Oort cloud is so far from the Sun and the gravitational influence that passing stars can affect it. Objects within the cloud are affected by any passing stars and some have their orbits changed with amazing results. Some of these objects end up being sent into the inner section of the Solar System as comets, others head off in the other direction out into space.
In fact many of our famous comets are believed to have originated from the Oort Cloud. Comet Hale-Bopp is one that is believed to have started it’s life in the cloud.
If you want to learn more about this intriguing cloud system then there are currently some excellent resources in the astronomy section of the BBC web site. If you’re quick there are even some shows on the BBC Iplayer but they will probably be ending soon. If you want to try and catch them whilst online and you are not in the UK, then you’ll need to try this technique – Watching the BBC Iplayer Abroad in 2012, there’s a little video which shows you the techniques to access the site from the USA.
Quick addition, been working in Spain for a while and obviously there’s been some developments with regards to the Oort cloud, which I’m sure you’ve all heard of. It’s being covered in the BBC news and I’ve been able to keep in contact from my temporary home in the Cost Brava using this technique – http://www.iplayerabroad.com/bbciplayer-in-spain-uk-proxy/, there are other options but this has worked for me.