Cosmonaut Versus Astronaut – What’s The Difference?

The terms cosmonaut and astronaut have 70 years of blood, sweat, and tears soaked into them as humankind reached for the stars. While these titles seem similar, few understand the uniqueness of each. What, then, are the differences between a cosmonaut and an astronaut?

Cosmonaut vs Astronaut

Origins of the Space Race

Shortly after the end of World War II, the Cold War began between two world superpowers. The United States and the Soviet Union became locked in a race for superiority that spilled over into the quest to explore the final frontier.

By the late 1950s, both countries had developed space programs to reach new heights. The Soviet Union was the first to send an object into space. Sputnik, named after the Russian word for traveler, became the first man-made object placed in Earth’s orbit.

The Space Race
The Space Race. (Image credit:  Tdadamemd  on Wikimedia Commons  CC BY-SA 3.0)

The United States was able to respond with a satellite of its own, but the Soviets widened the gap with the launch of Luna 2, the first space probe to reach the Moon. It wasn’t long before both programs were sending men into space.

The United States ultimately “won” the space race by being the first country to put a man on the Moon in 1969. The brave explorers from both countries needed to have titles fitting their purpose, as such feats had never been done before.

Cosmonaut Versus Astronaut

With the United States and the Soviet Union effectively at war, the two countries were unwilling to share information. As a result, there were many differences between the two space programs. One of the most notable diversions was the difference in naming conventions.

What Is a Cosmonaut?

Expedition 65 Russian cosmonaut Pyotr Dubrov performs the traditional door signing at the Cosmonaut Hotel
Expedition 65 Russian cosmonaut Pyotr Dubrov performs the traditional door signing at the Cosmonaut Hotel. (Image credit: NASA)

The Soviet Union was the first country to send a man into outer space. In April of 1961, Yuri Gagarin completed one orbit of the Earth. To celebrate his position and achievement, the Soviet space program awarded him the title cosmonaut.

This title would be used for every future Soviet and Russian spacefarer that completed the rigorous training program of the Russian Space Agency.

What Does Cosmonaut Mean?

The term cosmonaut (космонавт in Russian) is derived from two Greek words: “kosmos,” meaning universe, and “nautes,” meaning sailor. A cosmonaut is therefore effectively an individual who sails the universe. It is still used even today.

What Is an Astronaut?

The Original Seven Mercury Astronauts pose beside an Air Force F-102 jet
The Original Seven Mercury Astronauts pose beside an Air Force F-102 jet. (Image credit: NASA)

It was but three weeks later that the United States was able to send their own man into sub-orbit around the Earth. Alan Shepherd completed the historic journey in May of 1961 and set the American space program into full swing. John F. Kennedy would announce shortly after that the United States would have a man on the Moon before the end of the decade.

The Americans chose a similar but altogether different title for Shepherd as he left the confines of Earth for the first time. Perhaps to show differentiation from their Soviet rivals, the United States chose the term astronaut for its space explorers.

What Does Astronaut Mean?

The word astronaut is surprisingly similar to cosmonaut. While both incorporate the word “nautes” for sailor, the United States chose instead to use the word “astron,” meaning star. Thus, astronauts are forever known as star sailors.

This term has subsequently been adopted by both Canada and Japan for graduates of their respective space training programs.

What Is the Difference Between a Cosmonaut and an Astronaut?

When it comes down to it, there doesn’t appear to be any difference between cosmonauts and astronauts. Both are explorers of the region beyond the Earth and have accomplished many of the same feats. Astronauts and cosmonauts frequently work together in this day and age to unlock the mysteries of the universe on the International Space Station.

However, there are some notable differences between the two that are worth pointing out.

Informal portrait of STS-71Mir cosmonauts and astronauts
Informal portrait of STS-71Mir cosmonauts and astronauts. (Image credit: NASA)

Requirements To Become a Cosmonaut

There are several considerations that must be met before someone is even considered for the cosmonaut program:

  • Be a Russian citizen
  • Be 35 or younger
  • Can be either a man or a woman
  • Be between 5 and 6.25 feet (1.5 to 1.9 meters) tall
  • Weigh between 110 and 200 pounds (50 to 90 kilograms)
  • Be free of any chronic health conditions
  • Have both a university degree and experience in engineering, scientific, or flight specialties. Those with experience in aviation, rockets, or the space industry are given special consideration
  • Speak fluent Russian and English

Requirements To Become an American Astronaut

Requirements to become an astronaut were once more stringent, as spacecraft were quite small during the early days of space exploration. Today, anyone can apply to be an astronaut as long as they meet the following requirements:

  • Applicants must be a United States citizen
  • Possess a master’s degree in a STEM field, including biological science, physical science, engineering, computer science, or mathematics, from an accredited institution.
  • Have at least two years of experience in one of the fields listed above or at least 1,000 hours of pilot-in-command time on a jet aircraft.
  • Meet the requirements of the NASA long-duration flight astronaut physical

The Training Program

Both programs have their own training programs that those wishing to venture into space must complete.

For Cosmonauts

At the Gagarin Cosmonaut Training Center in Star City, Russia.
Expedition 46-47 crewmember Yuri Malenchenko of the Russian Federal Space Agency (Roscosmos) signs in for his qualification exam. (Image credit: “At the Gagarin Cosmonaut Training Center in Star City, Russia” by NASA Johnson on Flickr CC BY-NC 2.0)

The Russians who pass the initial requirements to enter cosmonaut training are sent to the Gagarin Cosmonaut Training Center in Moscow. At Star City, potential cosmonauts have to undergo an intense program. Through many stages of the program, individuals perform many space simulations, testing with space suits, and flights both with and without gravity.

For Astronauts

New Astronaut Candidate's First Day at NASA's Ellington Field
New Astronaut Candidate’s First Day at NASA’s Ellington Field. (Image credit; NASA)

American candidates head to Johnson Space Center in Houston for their training. Through hundreds of hours, these individuals are taught everything there is to know about spaceflight and the equipment used while in space. They’re also taught survival skills, medical skills, and how to speak an additional language (typically Russian).

What About Commercial Flights to Space?

With a push for even more individuals to travel to space, many companies are developing spacecraft that will take civilians out of the Earth’s atmosphere. While this is indeed an exciting venture, simply reaching space does not make one an astronaut or cosmonaut.

As mentioned earlier, those given the title of cosmonaut or astronaut must first meet specific requirements and pass a rigorous series of tests to be bestowed the title.

What Do Other Nations Call Their Space Explorers?

Although countries like Canada and Japan have chosen to use the term astronaut for the men and women that complete their respective training programs, a few countries have chosen names of their own.


China is quickly rising up as a major player in modern space exploration. The country has chosen the term taikonaut for those meeting the requirements to travel into space. Taikonaut is a hybrid of the Chinese word for space and the Greek word for sailor.


India is another country with an impressive up-and-coming space program. When they start sending people into space, they’ve chosen the word vyomanaut to represent them. The Greek word for sailor is combined with the Sanskrit word for sky.


France has sent ten people into space and chooses to use the French word spationaute for their title. This word is a French take on the Latin word “spatium” for space and the Greek “naut” for sailor.

What Do Other Nations Call Their Space Explorers

Final Thoughts

Simply put, cosmonauts and astronauts are in many ways the same yet very different. Each title represents its respective journey from the origins of the space program to modern day. While their requirements and training programs are different, the men and women who told these titles share experiences that most of us can only dream about.

Today, these titles are worn as badges of honor for all those who have gone before. They are kept separate out of respect for each country’s contribution to the many seemingly impossible things that allow us to continue to draw ever closer to the stars.

About Noah Zelvis

Noah is a content writer who has had a love of all things astronomy for as long as he can remember.
When not reaching for the stars, you’ll likely find Noah traveling or running.