astronaut in space waving

11 Interesting Facts About Astronauts

Last Updated: December 5, 2023

Astronauts…those that explore the vast beyond, travelling up and above limits the majority of us will never see with our own eyes, viewing the Earth from a perspective we can only enjoy from photographs. The adventurous ones becoming the sailors of the stars, well quite literally seeing as the word itself comes from the Ancient Greek “astron nautes” which translates to “star sailor”. But they don’t just go through some rigorous training to get in a rocket and blast off and then that’s it, there’s so much more to being an astronaut than what we know!

Such as did you know astronauts actually age slower than those of us on Earth?!  Oh yes, I’m serious! So let’s talk about it and more!

Fact #1 Astronauts age a little slower than people on Earth

Now this one might seem a bit brain boggling, to begin with, but I promise it’ll make sense. Fundamentally this happens due to time being relative, and I’m sure this is a term you’re familiar with thanks to Einstein and his theory of relativity. 

Time is curved, it isn’t flat, and it can be influenced by both matter and energy, so depending upon our own position and speed, time itself can seemingly move faster or slower in comparison to other people’s experiences from our own. So if we take the Astronauts onboard the International Space Station (ISS), they will age ever so slightly slower than those on us here on Earth. “But why?” I hear you ask! Well, scientists have noted how time seems to slow down near huge objects (such as a planet, eg: Earth) because the object’s gravitational force bends space-time. 

Basically, this means that time slows down the closer to the Earth we get due to its gravitational pull, and this is why those on the ISS experience time slower than us on Earth, and why they will age slower! Granted the differences aren’t huge, it would only be a fraction of a second if that.

Fact #2 Astronauts are required to learn the Russian language

To work onboard the ISS, Astronauts must be proficient in speaking, reading, and understanding the Russian language. Not all Astronauts choose to learn it, especially those not going on missions to the ISS, but some Astronauts choose to prepare themselves and take lessons regardless due to the ISS being the main focus of missions for the past 20 years.

The ISS is split into 2 segments, the United States Operating Segment (USOS) and the Russian Segment (RS). Both Astronauts and Cosmonauts must be sufficient in English and Russian to be able to communicate effectively with one another and to also operate both segments and communicate with specialists back on Earth. Crew members are launched to the ISS (and come back to Earth) in what’s known as the Russian Soyuz rocket.

This meant that Astronauts had to become sufficient in the Russian language to not only use the equipment, but if something was to go wrong, they needed to be able to communicate with the specialists on the ground that would be able to assist them.

Fact #3 Astronauts have to exercise every day in space

Whilst on Earth, we are up against the force of gravity, this means our muscles and bones are constantly at work to support our body. However, in space, there is a significant lack of gravity and thus our bones and muscles don’t have to do any work, this, in turn, can cause them to become incredibly weak. 

Because of this, Astronauts must exercise at least 2 hours every single day on equipment to make sure their bones and muscles don’t suffer too much damage from the effects of zero gravity. They use 3 main pieces of equipment which are a treadmill, a cycle ergometer, and a Resistance Exercise Decide (RED for short).

On top of this, zero gravity affects bodily fluids and this, of course, includes plasma. Plasma gets lost throughout the body and this causes less oxygen to get carried around and this puts Astronauts are risk of fainting, yet exercising has been found to increase plasma levels, thus creating more red blood cells, which results in an ample amount of oxygen being carried around the body. 

So fundamentally exercising helps Astronauts from becoming weak, which would result in them not being able to work as effectively, and also lowers their chances of fainting – which is actually something they are prone to in zero gravity!

Astronaut Chris Cassidy exercising on the ISS

Astronaut Chris Cassidy exercising onboard the ISS.

Fact #4 Astronauts grow up to 3% taller in microgravity

Thanks to the gravity here on Earth the disks in your spine are compressed together. So when an Astronaut is up in space where there is close to zero-gravity, the disks become decompressed and thus result in that individual becoming temporarily taller – until the effects of gravity get a hold of them when they return, even though it still takes a few months for an Astronaut to return to their normal height!

Fact #5 An Astronaut's heart changes shape due to microgravity

Another aspect of health that the Astronauts have to be wary of is their hearts! Scientists have found that long periods of time in space have resulted in Astronauts’ hearts becoming more spherical in shape. This is another effect of microgravity, and whilst it is temporary as the heart will go back to its normal shape once back on Earth, it is believed that the spherical shape proves that the heart doesn’t work as efficiently in microgravity.

Regardless of the heart returning to its normal shape once back on Earth, prolonged space travel and/or exposure to microgravity can result in heart problems. 

Fact #6 Not all Astronauts are called Astronauts

That’s right! Not all of our beloved star sailors are known are Astronauts, there are also Cosmonauts and Taikonauts! Fundamentally though they all do the same job just with different titles, but to become an Astronaut you must be trained by either NASA (USA), ESA (Europe), CSA (Canada), or JAXA (Japan), Cosmonauts are specifically trained by the Russian Space Agency, and Taikonauts are trained in China!

Rather interestingly the difference in names between Astronaut and Cosmonaut comes down to the famous ‘Space Race’ between America and Russia. But whilst each country has their own guideline on becoming an Astronaut or Cosmonaut, it very much is the same job!

Fact #7 Astronauts' fingernails can fall off

Bit of a toe-curling one this is to think about, I know! But it’s true, Astronauts do have to deal with their finger nails falling out! This is down to how heavy and bulky their space gloves are. This causes a lot of pressure on their fingers but also causes the circulation to either to get restricted or cut off completely, and this is why you’ll find a lot of Astronauts suffering from blisters and especially their nails falling out over time!

Because of this, before launching off into space, some Astronauts have been known to pull out their own nails in preparation so they can avoid both injury and infection. Ouch!

Fact #8 Survival Kits for Russian Cosmonauts used to contain shotguns

Between the years 1986 and 2007, Cosmonaut survival kits were kitted out with shotguns on space missions. Granted no one needed a shotgun to be shooting any bears in space, but the intention was for, if upon re-entry to Earth, the crew landed somewhere remote and potentially hostile with any aggressive wildlife, they would have a level of protection until they were rescued!

This all came about thanks to Cosmonaut Alexey Leonov who landed 600 miles from his planned landing site due to a mechanically faulty capsule. He only had a pistol on him at the time but was completely terrified of the bears and wolves he knew called the area home, whilst he never did encounter any, the fear was enough for him to make sure all Cosmonauts were equipped with an adequate survival weapon should the same thing happen to them on future missions. 

Fact #9 Astronauts do a lot of training in water!

Naturally, there will always be plenty of people applying to become an Astronaut, but of course, only very few get selected! And for those that do get selected, straight from the get-go, their training is rigorous! Almost immediately into their training candidates have to swim 3 full lengths of a 25-meter swimming pool, and then proceed to tread water for 10 minutes after completing those laps.

However, candidates can take as long as they like to finish the 3 laps and can use one of three strokes: breaststroke, freestyle, and sidestroke. Oh, and they have to wear shoes and a 250lbs flight suit whilst doing so!

Astronauts must get scuba certified early on due to the micro-environment training that prepares them for the weightlessness of space, and they spend a lot of time underwater at the NASA Neutral Buoyancy Laboratory for that.

Astronauts wear their spacesuits and are accompanied in the pool by two safety divers as they move around and practice various exercises or skills that they’ll be using in space.

Fact #10 Astronauts see 16 sunrises per day

Due to the fact it only takes the ISS roughly 90 minutes to fully orbit the Earth, Astronauts on board are treated to a sunrise and sunset every 45 minutes. As you can imagine this can make trying to get a decent night’s sleep quite difficult, especially with the sun frequently popping back into view.

An Astronaut is expected to get between 6 and 8 hours of sleep but when you have 45 minutes of light followed by 45 minutes of dark, this easily disrupts an Astronauts’ natural day and night cycle!

To try and get around this the ISS has its lights turned up to full brightness for roughly 15-16 hours and then those lights at dimmed for between 8-9 hours when it’s time to sleep and rest.

Naturally, this doesn’t stop the sun from appearing time and time again so a lot of Astronauts will find themselves using sleep masks to block out as much light as possible and to try and keep their day and night cycle as regular as possible. 

astronaut looking out of the cupola

Astronauts can see up to 16 sunrises per day from the ISS's cupola module.

Fact #11 Astronauts need to wear specialized glasses in space

Astronauts’ experiences in space are filled with remarkable adaptations, including how they deal with changes in their vision. In the unique environment of space, prolonged exposure to microgravity can lead to vision issues, a condition NASA refers to as Spaceflight-Associated Neuro-ocular Syndrome (SANS). This spaceflight-related health condition has been a critical area of study, especially considering plans for extended missions like a trip to Mars.

To address these vision changes, astronauts use specially designed glasses. These are not just ordinary eyewear but are specifically tailored to counteract the effects of SANS. An interesting historical note is that even John Glenn, a renowned astronaut, carried a pair of “space anticipation glasses” with him. These glasses help astronauts maintain visual acuity, a vital necessity for the intricate and demanding tasks they perform in space.


Written by Amy Gent

A spiritual witch and Mother of 2, preferring the lore of my own reality! Outside the weird and wonderful world of my craft, I like to cosplay and fully dive into the fantasy genre across all forms, from books to video games and everything in between. Find her on Instagram.

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