Lightning is electricity inside a cloud. Scientists do not Know exactly what makes this electricity. But they know that the electricity inside a cloud can be as much as much ar 100 million volts. From this extremely strong electricity, a lightning bolt, like a streak of bright light, comes down from the sky. Its temperature can reach 50,000 degrees Fahrenheit within a two millionths of a second. That's almost five times the temperature on the sun's surface. The lightning bolt is very quick. It can move at a speed of 84,000 miles per second. A rocket traveling at this Speed would reach the moon in 2.5 seconds.