By Marlo Anderson – The Tech Ranch
Ever wonder why satellites don’t just fall out of the sky? Here’s the surprise: they are falling. They’re just moving sideways so fast that they keep missing Earth.
Space Is Closer Than You Think
Space officially begins about 62 miles (100 km) up. That’s about an hour’s drive, if you could drive straight up. Getting there is the easy part. Staying there is the hard part.
Going Up Isn’t Enough
Launch straight up and shut off the engine, and gravity pulls you right back down. To stay up, you need sideways speed, and a lot of it.
Newton’s Cannonball
Isaac Newton pictured a cannon on a very tall mountain. Fire a cannonball sideways and it curves down and lands. Fire it faster and it lands farther away. Fire it fast enough and Earth curves away as fast as the ball falls. That’s an orbit: falling and always missing the ground.
How Fast Is Orbit?
About 17,500 mph (28,000 km/h), roughly 5 miles every second. At that speed the International Space Station laps Earth about every 90 minutes, so astronauts see about 16 sunrises a day.
Up First, Then Sideways
That’s why rockets launch straight up to get out of the thick lower air, then tip over and speed up sideways. Empty stages drop away to shed weight, and the whole trip to orbit takes under 10 minutes.
Bonus Fact: Gravity at the Space Station
Gravity at the space station is still about 90% as strong as on the ground. So why do astronauts float? That’s the next video in the series.
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.
