An interesting piece at http://arxivblog.com/?p=596 'Do nuclear decay rates depend on our distance from the Sun?' … is a question that came up in a recent Study Group meeting in London. Decay rates of elements have always been thought to be constant regardless of ambient conditions. However, at the same time it is long known that decay rates can be influenced by powerful electrical fields – and we can all see electricty in the atmosphere in the form of lightning. It has been noticed that there are periodic variations in decay rates of silicon-32, for example, or radium-226 – as observed in laboratories (not in the natural world). It seems the decay rate may modulate itself with earth's distance from the Sun – but why might that be? The decay rate of maganese-54 in a laboratory was seen to decrease dramatically during a solar flare (see also arxiv.org/abs/0808.3283 ). A commenter adds … it is well known that changes in the cosmic ray flux have a big impact on the rate of production of C14 in the atmosphere.