By Marlo Anderson – The Tech Ranch
Ask most people why astronauts float and they’ll say there’s no gravity in space. Not quite. At the space station, gravity is still about 90% as strong as it is on the ground.
Gravity Is Still There
The International Space Station flies about 250 miles (400 km) up. Drawn to scale, that’s barely above Earth’s surface, and gravity there is still about 90% of what you feel at home.
It’s All About Falling
Ever feel floaty on a big drop ride? When you and everything around you fall together, nothing pushes back on you. A bathroom scale would read zero. That’s what weightlessness really is: free fall.
Falling Around Earth
The space station is falling the whole time. But it’s also flying sideways at about 17,500 mph, so it keeps missing Earth. Astronauts fall right along with it, so they float.
Practice on a Plane
NASA trains astronauts on airplanes that fly big arcs. Over the top of each arc, everyone floats for about 20 seconds, then the plane pulls out and does it again.
Floating Has a Cost
Without weight to carry, muscles and bones get weaker. Astronauts exercise about 2 hours every day, strapped to a treadmill with bungee cords, and they can still lose about 1% of their bone density a month.
Bonus Fact: Round Flames
On Earth, hot air rises and stretches a candle flame into a teardrop. In microgravity there’s no “up,” so a flame becomes a round, blue ball.
More Space Travel, Explained
This is part of my Space Travel Explained series: big space questions, answered in plain English with simple animations. Watch the whole series on YouTube and subscribe to The Tech Ranch so you don’t miss the next one. Short on time? Here’s the quick Short version.
Found this helpful? Give the video a thumbs up on YouTube. Got a space question you’ve always wondered about? Ask it in the YouTube comments and it might be the next video.
