Jewel made entirely by hand by the Italian craftsman Gianmarco Fontana. This 925 Silver ring depicting Lost in space is part of the “Skulls” collection.

An astronaut or cosmonaut is a human being who travels in space or is transported by something that does, the prime subject of human space exploration.

The criteria for determining the meaning of "space travel" are different in the different cultures of the individual countries involved. In the United States, astronauts are considered to be those who exceed an altitude of 50 miles (about 80 km), in Russia for space flight we mean an orbital trajectory (geocentric orbit) or that the machine must make at least one revolution around the Earth.

The International Aeronautical Federation (FAI), on the other hand, defines space flights as those that exceed 100 km; for this reason the total number of astronauts differs from source to source. As of June 20, 2011, a total of 529 people went into space, according to the American definition, where they totaled over 30,000 days, including more than 100 days of spacewalking. On the same date there are 523 "astronauts" according to the FAI. The people who have made space travel to date come from 38 countries.