Scientists Say: Astronaut

Astronauts are people who go to space 

an astronaut wearing a space suit takes a selfie as they drift above the Earth

Here, NASA astronaut Barry Wilmore is on a spacewalk outside the International Space Station in 2015.


Astronaut (noun, “AST-roh-not”)

An astronaut is someone who travels to or works beyond Earth’s atmosphere. The term comes from the Greek words meaning “space sailor.”

In 1961, Russian Yuri Gagarin became the first person to fly in space. (Russian astronauts are called “cosmonauts.”) Later that year, Alan Shepard became the first U.S. astronaut in space. In 1969, astronaut Neil Armstrong set foot on the moon. And 1983 launched the first female U.S. astronaut, Sally Ride. NASA’s record holder for most time spent in space is Peggy Whitson. She has clocked a total of 665 days in space.

Today, astronauts work on the International Space Station, or ISS. That floating laboratory orbits Earth about 420 kilometers (260 miles) above the ground. Astronauts typically spend about six months there. Many of these astronauts have come from the United States and Russia. But Europe, Japan, Canada and other parts of the world have sent astronauts to the ISS as well.

Some astronauts are pilots. Their job is to drive spacecraft. Other astronauts specialize in doing experiments or launching satellites. Most research on the ISS tests how things work in a weightless, or microgravity, environment. For instance, how flames burn or how plants grow differently in space. Astronauts do most of their work inside the space station. But sometimes they have to go on a spacewalk to build or fix something outside the ISS. This involves putting on a space suit and getting tethered to the space station so they don’t float away.

There are a few requirements to become an astronaut. The first is a master’s degree in science, technology, engineering or math. Astronauts must also have at least two years of work experience. Or, they must have logged at least 1,000 hours piloting a jet aircraft. People of all ages can become astronauts. But they must pass a physical exam. Why? Living in space is very hard on the body. Astronauts must exercise for a couple of hours a day to maintain their fitness. So, people must be very healthy to safely go to space.

In a sentence

Apollo astronauts left mementos, science experiments and trash on the moon.

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Maria Temming is the Assistant Managing Editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

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