Io's metallic core makes up approximately 20% of its mass. Depending on the amount of sulfur in the core, the core has a radius between 350 and 650 km (220â400 mi) if it is composed almost entirely of iron, or between 550 and 900 km (340â560 mi) for a core consisting of a mix of iron and sulfur.
The early history of the automobile can be divided into a number of eras, based on the prevalent means of propulsion. Later periods were defined by trends in exterior styling, size, and utility preferences. In 1769 the first steam-powered automobile capable of human transportation was built by Nicolas-Joseph Cugnot.
Exactly who invented the automobile is a matter of opinion. If we had to give credit to one inventor, it would probably be Karl Benz from Germany. Many suggest that he created the first true automobile in 1885/1886. Below is a table of some automobile firsts, compiled from information in Leonard Bruno's book Science and Technology Firsts (Detroit, c1997) and About.com's History of the Automobile.