A cosmonaut is an astronaut from Russia or the former Soviet Union. While Americans call their space travelers astronauts, Russians use the word cosmonaut for the exact same job: piloting spacecraft, conducting experiments in orbit, and exploring beyond Earth's atmosphere.

The word comes from Greek roots meaning “sailor of the universe.” During the Space Race of the 1950s and 1960s, when the United States and Soviet Union competed to achieve milestones in space exploration, Soviet cosmonaut Yuri Gagarin became the first human to journey into space in 1961. American astronaut Alan Shepard followed just weeks later.

Today, cosmonauts and astronauts work together aboard the International Space Station, even though their countries use different words for them. They train together, eat meals together, and conduct the same kinds of scientific research. A Russian crew member is still called a cosmonaut, while an American, European, or Japanese crew member is called an astronaut, but they're all doing the same extraordinary work: living and working in space.

You might also encounter the term taikonaut, which refers to space travelers from China. All three words describe people brave and skilled enough to leave Earth behind, even if just for a while.