The secrets of lightning

Lightning is a force of nature. Traveling at a speed of 100,000 km/h, with a temperature five times that of the Sun's surface, it strikes the Earth millions of times a day. But what makes lightning? Does it have a purpose? The phenomenon has puzzled generations of scientists for centuries, from Benjamin Franklin to Nikola Tesla. Today, in a bid to unravel its true nature, researchers are trying to achieve something once thought to be impossible: capturing lightning.