"Scott Kelly, an American astronaut, went to space in the 1990s and 2000s. In 2015, he set the record for the total number of days spent in space. Learn more about Kelly's life as an astronaut!"--

Nikola Tesla was a scientist and inventor in the late 1800s and early 1900s. Among his many inventions and experiments, he helped create the modern electricity system. Learn more about Tesla's life as a famous inventor.