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.
In 1886, Karl Benz developed a petrol- or gasoline-powered automobile. This is also considered to be the first production vehicle as Benz made several other identical copies. At the turn of the 20th century electrically powered automobiles appeared but only occupied a niche market until the turn of the 21st century.
The history of the automobile is very rich and dates back to the 15th century when Leonardo da Vinci was creating designs and models for transport vehicles. There are many different types of automobiles - steam, electric, and gasoline - as well as countless styles. 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.