Very interesting and definitely worth a look. Makes you realise how puny we are. http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/ 72/73's Ian C. Purdie Budgewoi N.S.W. Australia - Co-ords S33�14', E151�34' VK2TIP "I'll give ya the TIP mate" QRP-L #1978. SOC #171 FP#91 http://www.electronics-tutorials.com/