This article is for students grades 5-8.
What is Pi?
Pi is a number. You might know it as 3.14 or the symbol π. But it's way more than that!
What Makes Pi Special?
Pi is an irrational number. That means it goes on forever and it never repeats its sequence of numbers. Pi has been calculated to more than one trillion digits! But NASA scientists and engineers use far fewer digits in their calculations. Usually, the approximation of 3.14 is precise enough.
Pi is the circumference of a circle divided by the circle's diameter. Pi is the same for any circle, no matter how big or small. It is a mathematical constant.
———————————————————————————————
Words to Know
irrational number: a number that cannot be expressed as a simple fraction
circumference: the distance around a circle
diameter: the distance of a straight line across the center of a circle
———————————————————————————————
How Is Pi Used?
Pi is used in lots of ways. It's fundamental for calculating anything that involves circles, curves, or spheres. It's used in geometry, physics, engineering, and even computer science.
How Does NASA Use Pi?
NASA missions depend on pi. Let's look at a few examples.
Astronauts returning home from the International Space Station use parachutes to slow their spacecraft down for a safe landing. But just how big do the parachutes need to be? NASA uses pi to calculate the circular area required to slow a spacecraft as it moves through the atmosphere.
Planetary scientists use pi to learn about the materials inside a planet or asteroid. They use pi to determine the object's volume. Combined with the object's mass, they can determine the density of the object. Since we know the densities of planetary materials like rock, ice, and metal, scientists can make informed guesses about what the planet or asteroid might be made of.
Did you know that spacecraft fuel tanks are usually sphere-shaped? Rocket scientists use pi to figure out how much fuel a spacecraft will need. They also use pi to compute how much fuel is available in spacecraft tanks and how quickly that fuel travels through their cylindrical fuel lines.
