Spontaneous flashes of 'microlightning' between bubbles of gas could explain will-o'-the-wisps - flickering lights that can appear on marshlands. Researchers blew tiny bubbles of methane and air into water, where smaller bubbles took on a negative charge and larger ones, a positive charge. As the charges equalized, they produced a small zap of electricity and a flash of light. This could explain why the ghostly-looking lights appear over methane-rich bogs.