We used to know what advertising was. It was that stuff in the margins, in the ad breaks. But in recent years, it has begun colonising every space it can. US ad wizard Mark Fenske, the guy behind the Nike campaigns, calls advertising "maybe the most powerful art form on Earth". And the Earth ain't the end of it. Not so long ago, Pizza Hut stamped its logo on a rocket to the moon. Earlier this year, Doritos announced it would beam its ads into space.