In 1961, Yuri Gagarin became the first person to venture beyond Earth's atmosphere. Since his journey, about 450 people – astronauts, civilians, and "space tourists" – have explored space. Follow this slideshow to learn about notable firsts for space exploration.

Photo source: NASA

Photo source: NASA

Photo source: NASA

Photo source: NASA

Photo source: NASA

Photo source: NASA

Photo source: NASA

Photo source: NASA

Photo source: NASA

Photo source: NASA

Photo source: NASA

Photo source: NASA

Photo source: NASA

Photo source: fas.org

Photo source: spacedaily.com

Photo source: NASA

Photo source: spacefacts.de