ClassX Video Lessons Why zero gravity is a myth: The amazing science of ‘floating’ astronauts | NASA’s Michelle Thaller
Have you ever wondered why astronauts seem to float around in the International Space Station (ISS)? Many people think it’s because there’s no gravity in space. This idea can be quite puzzling, especially when we see astronauts moving as if gravity doesn’t exist. In this article, we’ll dive into what gravity is like in space, how orbits work, and why astronauts appear to be weightless.
Astronauts on the ISS are about 200 miles above the Earth. Despite what some might think, they are not far enough from Earth to escape its gravity. If you could build a super tall building reaching 200 miles up, you’d still weigh about 80% of what you do on the ground. This shows that gravity is still strong at that height.
To understand why astronauts float, we need to talk about orbits. The ISS travels around Earth at a speed of about 17,000 miles per hour. This speed is key to staying in orbit. When astronauts are on the space station, they aren’t weightless because there’s no gravity; instead, they’re in a state of free fall towards Earth.
Think about dropping a ball. It falls straight down because of gravity. Now, imagine shooting that ball from a cannon. It will still fall, but it will go a distance before hitting the ground because it has an initial speed. If you shoot the ball fast enough, it could travel even farther before falling.
Now, consider a rocket. A rocket can launch something at such a high speed—17,000 miles per hour—that as it falls towards Earth, the planet curves away beneath it. This ongoing free fall while moving forward quickly is what makes an orbit.
Astronauts on the ISS are constantly in free fall, like a skydiver. They’re falling towards Earth, but because they’re moving so fast, they keep missing it. This creates the feeling of weightlessness. Everything in orbit, like satellites and the Moon, experiences the same thing: they’re all falling due to gravity but moving fast enough to avoid crashing into Earth or other objects.
In conclusion, the idea that there’s no gravity in space is a misunderstanding. Gravity is definitely present, even at the ISS’s altitude. The weightlessness astronauts feel is because of their high-speed free fall towards Earth, which keeps them from hitting it. Understanding this helps us appreciate how orbits work and the movement of celestial bodies in space.
Conduct a simple experiment to understand gravity’s effect. Use a small ball and a ramp to simulate how objects fall. Measure the time it takes for the ball to roll down the ramp at different angles. Discuss how gravity affects the speed and direction of the ball. Relate this to how gravity works in space.
Build a model to demonstrate how orbits work. Use a string and a small ball to represent a satellite orbiting Earth. Swing the ball in a circular motion and observe how it stays in orbit. Discuss how the speed of the ball affects its orbit, similar to the ISS orbiting Earth.
Use an online simulation tool to explore free fall in space. Experiment with different speeds and altitudes to see how they affect an object’s orbit. Discuss how astronauts experience weightlessness due to continuous free fall, and relate this to the simulation results.
Watch a video of astronauts on the ISS and discuss their activities in a weightless environment. Identify how they adapt to weightlessness and the challenges they face. Reflect on how understanding gravity and free fall helps them perform tasks in space.
Take a quiz to test your understanding of gravity and orbits. Answer questions about the concepts discussed in the article, such as the nature of weightlessness and the mechanics of free fall. Review your answers and discuss any misconceptions with your classmates.
Gravity – The force that attracts objects with mass toward each other, especially the force that makes things fall to the ground on Earth. – Gravity is what keeps the planets in orbit around the Sun.
Space – The vast, seemingly infinite expanse that exists beyond the Earth’s atmosphere, where stars, planets, and other celestial bodies are located. – Telescopes allow us to observe distant galaxies in space.
Orbit – The curved path of an object around a star, planet, or moon, especially a periodic elliptical revolution. – The Moon’s orbit around Earth takes about 27 days to complete.
Astronauts – People who are trained to travel and work in space. – Astronauts aboard the International Space Station conduct experiments in microgravity.
Weightlessness – The condition experienced in free fall where the effects of gravity are not felt, often occurring in space. – In the state of weightlessness, astronauts can float freely inside the spacecraft.
Free Fall – The motion of a body where gravity is the only force acting upon it. – Skydivers experience free fall before deploying their parachutes.
Earth – The third planet from the Sun in our solar system, home to all known life. – Earth is the only planet in our solar system with liquid water on its surface.
Speed – The rate at which an object moves, calculated as distance divided by time. – The speed of light is approximately 299,792 kilometers per second.
ISS – The International Space Station, a large spacecraft in low Earth orbit where astronauts live and work. – The ISS orbits Earth approximately every 90 minutes.
Celestial – Relating to the sky or outer space, especially as observed in astronomy. – Celestial bodies like stars and planets can be observed with a telescope.
