Radio waves can bounce off anything metalic the ionosphere lies just above the atmosphere ionised particals in a gas reflect radiation same as the moon.
So the idea is to point a directional beam type antenna at the moon and bounce your signal back down to earth at say 30 degrees and maybe hit australia.
the ionosphere is more localized
This has been practised since the 1930s
Dont know if it would work with the london to brighton run tho 
Hehe, that brings back memories! Lets just say at the time I didn't have the required licences to it though.....
I also used to practice shooting skip with the
CB, my trusty (now just rusty) binatone 5star rig, 50+ watt burner and Firestick twig. I had some great (if a bit weak and hissy) conversations with different countries during some particularly strong solar activity, a number of years ago. had the USA, Alaska, Italy and once Japan (I think..) but lack of a common language meant short conversation.
I guess some things never change though, right now I'm typing this on a laptop running off a car battery and AC inverter, connected via a directional antenna WIFI link, to my internet connection at my house, while I'm working on one of my empty properties a few streets away. heh!

I was just going to listen to my MP3 collection, but figured I might as well use the shoutcast streams.
Ahwell, fag and tea break over, but at least I have streaming internet radio to keep me going for a few hours.

SS